forest nursery handbook - british columbia · forest nursery handbook r. van den driessche 63409097...

Q BRITISH EDLUMBIR FORE5T SERVICE 8- '-. -,.- A V I C T O R I A , B.C. ,CANADA G., ,,..+,- - - ,

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i8 No. 48 1 9 6 9

F O R E S T N U R S E R Y

H A N D B O O K

R . v a n d e n D r i e s s c h e

63409097 11 BCMF R E S riN 48 1 4 4 9 c. 3

.H FOREST S E R V I C E DEPARTMENT OF LANDS, FORESTS, AND WATER RESOURCES

Brit ish Columbia

Forest Nursery Handbook

R . van den Driessche

Foreword

The f i r s t nursery t o produce conifers for reforestation purposes in British Columbia was established on She1 bourne Road (near Victoria) in 1927. Development of 8 acres of nursery a t Green Timbers started twyears later. Douglas-fir and Sitka spruce were grown a t bo th nurseries, and times of sowing a n d methods of seed covering were investigated a t the Shelbourne nursery.

During the following 20 years nursery area increased slowly, b u t the quality of seedlings produced showed signs of deterioration. An experiment t o t es t the value o f mineral f e r t i l i ze r s fo r improving seedling size and quality was s ta r ted , and some nursery soil analyses were made by R . H . Spilsburyl in 1947. These early experiments establ ished tile value of mineral f e r t i 1 izers and emphasized the necessity for continued work on maintenance of nursery s o i l f e r t i l i t y . Such work has been carried on almost continuously since 1947, although i t has been the responsibility of different people. The value of shavings and sawdust as organic amendments were investigated by t1.A.W. Knight?. A factorial experiment with mineral f e r t i l i z e r s was carried o u t a t Green Timbers by M. Schaedle, and Fl. Stewart tested several types of organic amendments a t the East Kootenay nursery3.

This handbook summarizes research work and nursery procedures developed since 1960 by the British Columbia Forest Service. Information has, in f ac t , been drawn from three sources , (1 ) the 1 i terature , ( 2 ) experiments carried o u t by Research ilivision, and ( 3 ) experience gained by Reforestation Division who operate tile nurseries. In particular, Mr. A . H . Bamford has provided information on current techniques and d a t a from Reforestation records, and Mr. J . Long and Mr. L.V. Pla t t have given assistance by virtue of their practical experience.

This handbook does not always attempt t o ,lay down exact instructions for every contingency in the way a manual does. Rather, i t attempts t o provide some general information on each topic so t h a t the reader obtains some idea of tile principles involved. More specific recommendations are usually included after the general section. Each topic is deal t with br ief ly , and probably inadequately i n many instances, b u t references are frequently cited so t h a t furtner information can soon be traced.

1 Forest Service Annual Report 1947, p . 24.

2 Forest Research Keview 1956 , p . 27; 1958, p . 36.

3 Forest Research Review 1959 , p . 42.

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Contents Page

1 . Sowing

1.1 General .......................................................... 1

1.2 S t r a t i f i c a t i o n r e q u i r e m e n t s ...................................... 1

1.2(a) Douglas fir ............................................ 1

1.2(b) Hemlock ................................................ 1

1 .2 (c ) S i t ka sp ruce ........................................... 2

1.2(d) White spruce ........................................... 2

1.2(e) Lodgepole p ine ......................................... 2

1.3 Time o f sowing ................................................... 2

1.3(a) Fa1 1 sowing ............................................ 2

1.3( b ) Spr ing sowing .......................................... 2

1.4 Sowing d e n s i t y ................................................... 3

1.5 Broadcast and d r i l l sowing ....................................... 4

1.6 Depth o f sowing., ................................................ 4

1.7 Covering seed .................................................... 4

1.8 Bed p r e p a r a t i o n .................................................. 5

2 . F e r t i l i z a t i o n

2.1 General .......................................................... 6

2.2 N ................................................................ 6

2.2(a) Time of N a p p l i c a t i o n .................................. 6

2.2(b) N source ............................................... 6

2.2( c ) Method o f a p p l y i n g N ................................... 7

2.3 P ................................................................ 7

2.3(a) P source ............................................... 9

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2.4 K ................................................................ 10

2.4( a) K source ............................................... 10

2.4(b) Method of applying K ................................... 10

2.5 Ca ............................................................... 11

2.6 Mg ............................................................... 11

3 . Soil pH

3.1 General .......................................................... 11

3.2 Changing soi 1 pH ................................................. 11

3.3 Examples of pH changing treatments ............................... 1 2

4 . Organic matter

4.1 General .......................................................... 13

4.2 Suitable organic amendments ...................................... 14

4.3 Sawdust .......................................................... 14

4.4 Unsuitable organic amendments .................................... 14

5 . Rotati on

5.1 General .......................................................... 14

5.2 Rotation i n conifer nurseries .................................... 14

6 . Weed control

6.1 General .......................................................... 15

6.2 Emergence spraying ............................................... 15

6.3 Seed bed spraying ................................................ 16

6.4 Transplant spraying .............................................. 16

S o i l s t e r i l i z a t i o n

7.1 General .......................................................... 17

7.2 Formaldehyde ..................................................... 17

7 .3 Ch lo rop ic r in ..................................................... 18

7.4 "Vorl ex" ......................................................... 18

7 .5 Root d i sease ..................................................... 18

8 . I r r i g a t i o n

8.1 General .......................................................... 18

8 .2 So i l mo i s tu re b locks ............................................. 19

8.3 Amount o f i r r i g a t i o n ............................................. 19

8.4 Cool ing by i r r i g a t i o n ............................................ 21

8 . 5 F r o s t p r o t e c t i o n by i r r i g a t i o n ................................... 21

9 . Growth p e r i o d i c i t y a n d r o o t / s h o o t r a t i o

9.1 General .......................................................... 22

9.2 L e n g t h o f growing period ......................................... 22

9.3 Shoot and root growth ............................................ 22

9 .4 Roo t / shoo t r a t io ................................................. 24

9 .5 Root regenera t ion ................................................ 24

10 . Transp lan t ing and roo t p run ing

10.1 General .......................................................... 25

10 .2 Transplan t ing .................................................... 25

10.3 Root p r u n i n g ..................................................... 25

Dormancy. frost hardiness. and l i f t i n g

11.1 Dormancy., ....................................................... 26

1 1 . 2 Frost hardiness .................................................. 26

11.3 Lifting .......................................................... 27

1 2 . Soil a n d plant tissue analysis

12.1 Soil analysis .................................................... 27

12 .2 Type of analysis for established and prospective nurseries ....... 28

12.3 Level o f soil nutrients .......................................... 29

12.4 Seedling tissue analysis ......................................... 30

12.5 Type of t issue analyzed .......................................... 31

12.6 Levels of tissue macronutrients .................................. 31

12.7 Levels o f tissue micronutrients .................................. 34

13 . Soil and seedling sampling

13.1 Soil sampling .................................................... 35

13.l(a) Intensity of sampling .................................. 35

1 3 . l ( b ) Determining sample p o i n t ............................... 35

13.1 ( c ) Depth of sampl ing ...................................... 35

13.1 ( d ) Accuracy of sampling ................................... 35

13 . l (e ) Bulking ................................................ 35

1 3 . l ( f ) Sample s ize ............................................ 36

13.l(g) Labelling .............................................. 36

13.2 Seedling sampling ................................................ 36

13.2(a) Size of sample ......................................... 36

13.2(b) Method o f sample ....................................... 37

13.2(c) Labelling .............................................. 37

13.2(d) Despatching ............................................ 37

Choice o f n u r s e r y s i t e s

14.1 General .......................................................... 14.2 Soi l texture ..................................................... 14 .3 So i l pH and o r g a n i c m a t t e r . ...................................... 14.4 Soi l depth ....................................................... 14.5 Water t ab le ...................................................... 14.6 Water supply ..................................................... 14.7 Topography ....................................................... 14.8 Cl imate .......................................................... 14.9 Examination o f p o t e n t i a l s i t es ...................................

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1 .

1 . Sowing

1 . 1 General

Conifer seed is stored a t a temperature of 0 t o 5 O F witn a moisture content of 5 t o 8 per cent. After removal from storage the seed will germinate i f provided with moisture, and i f the temperature i s h i g h enough. This germination tends t o be e r r a t i c , however, with a few seeds germinating each day. More uniform and rapid germination can be obtained in many species if seed is s t ra t i f ied before being placed under conditions suitable for germination. Stratification consists of allowing seeds t o imbibe water, usually by soaking for 24 hours, surface drying them, and then maintaining them a t 350 F for a specified length of time. Within limits, the longer the period of s t ra t i f icat ion the lower tile temperature a t which seed will germinate sa t i s fac tor i ly . White and black spruce seeds have been found t o germinate a t 350 F a f t e r a year ' s s t ra t i f ica t ion a t 35O F (MacArthur and Fraser, 1963). The e f fec t of stratif ication treatment may vary according to provenance, and i t has been suggested t h a t some Alberta provenances of white spruce show lower germination capacity, and more uneven germination ra tes , when s t r a t i f i ed t h a n when unstratif ied (Hellum, 1968):

Light may hasten germination of seed of some conifers. For example, exposure t o white l ight accelerates germination o f unstratified Douglas-fir seed a t 570 F and 68O F , t h o u g h above tnese temperatures the effect is not detectable (Richardson, 1959). Complete germination of lodgepole pine seed i s n o t obtained unless i t i s exposed t o white l ight for 5 minutes a f t e r soaking for s t ra t i f ica t ion (Ackerman and Farrar, 1965). The accelerating effect of l igh t on germination rate i s probably due t o i t s red 1 ight content (e.g. Johnson and Irgens-Mol l e r , 1964) . Red 1 ight stimulation of seed. germination i s . a well known phenomenon amongst higher plants. There i s no evidence t h a t seed germination i s reduced by ,1 ack o f 1 i g h t i n nursery practice, b u t the possible importance o f l ight should be recognized.

After s t ra t i f icat ion, a n d before 3nwing, seed may be coated with a sticking agent (such as "methocel" ) and some. material. which ei tiler has fungicidal properties (such as !'Captan" or "Arasan") , or adhesioa reducing properties (such as a1 uminum powder). The purpose of the aluminum. ?owder- i s to . f a c i l i t a t e seed flow through dri 11 seeding equipment.

1 . 2 S t ra t i f ica t ion requirements

1 . 2 ( a ) Doug1 as-f i r.

Strat i f icat ion of Douglas-fir seed results in more uniform and rapid germination. Soaking seed, for 24 hours, superficial drying, and s t r a t i f i c a t i o n a t 32-35O F f o r - 20 days results in a h i g h germination r a t e ' a t 7 7 O F. Rapid germination a t 50° F i s only obtained a f t e r s t r a t i f i ca t ion for 80 days or longer (Allen 1960) . Moisture content should be a t least 50 per cent of seed dry weight during s t r a t i f i ca t ion t o ensure a good chi l l ing effect .

1 . 2 ( b ) tiemlock.

Seed of hemlock should be soaked until i t a t t a i n s a moisture content o f 60 per cent (dry weight basis) . This means seed must

2.

be soaked f o r a minimum o f 35 hours. i4o is ture conten t shou ld be a t l e a s t 60 p e r c e n t o f seed d r y w e i g h t d u r i n g s t r a t i f i c a t i o n t o e n s u r e a good c h i l l i n g e f f e c t . Hemlock seed should be h e l d a t 32-35O F f o r 60 days. Germinat ion occurs fas tes t a t about 680 F and higher tempera- t u r e s r e d u c e t o t a l g e r m i n a t i o n ( B i e n t j e s , 1954).

1.2 ( c ) S i t k a s p r u c e .

Seed o f t h i s s p e c i e s s h o u l d be soaked f o r 24 hours, s u p e r f i c i a l l y d r i e d , and s t r a t i f i e d a t 32-35O F f o r 60 days.

1.2 (d) Whi te spruce.

Seed o f t h i s spec ies shou ld be soaked fo r 24 hours, s u p e r f i c i a l l y d r i e d , and s t r a t i f i e d a t 32-35O F f o r 60 days. It i s p o s s i b l e t h a t some provenances may germinate we1 1 w i t h o u t s t r a t i f i c a t i o n ( H e l l u m , 1 9 6 8 ) .

1.2 ( e ) Lodgepole p ine.

Seed o f t h i s s p e c i e s s h o u l d b e s o a k e d f o r 24 hours, s u p e r f i c i a l l y d r i e d , and s t r a t i f i e d a t 32-35O F f o r 60 days. A f te r soak ing , all seed must be exposed t o w h i t e l i g h t f o r 5 m i n u t e s b e f o r e s t r a t i f i c a t i o n .

1.3 Time o f sowing

1.3 (a ) Fa l l sow ing .

Seed i s n o t s t r a t i f i e d f o r f a l l sowing, but sown d r y . The t ime spent i n t h e seedbed over winter i s e f f e c t i v e l y a l o n g p e r i o d o f s t r a t i f i c a t i o n . G e r m i n a t i o n o c c u r s e a r l i e r than i s n o r m a l l y a c h i e v e d w i t h s p r i n g s o w i n g and consequently t h e 1-0 s tock ob ta ined i s l a rge . Doug las - f i r can no rma l l y be sown a f t e r t h e end o f O c t o b e r i n t h e s o u t h e r n c o a s t a l r e g i o n w i t h o u t f e a r o f g e r m i n a t i o n o c c u r r i n g b e f o r e t h e fo l lowing spr ing (van den Dr iessche, 1963a) . Whi te spruce i s f r e q u e n t l y f a l l - s o w n d u r i n g O c t o b e r i n n o r t h e r n B r i t i s h Columbia. F a l l s o w i n g o f h e m l o c k i n c o a s t a l n u r s e r i e s u s u a l l y r e s u l t s i n p o o r s t o c k i n g so t h a t e a r l y s p r i n g s o w i n g i s t h e m o s t s a t i s f a c t o r y p r o c e d u r e f o r t h i s s p e c i e s .

A disadvantage o f f a l l sowing i s t h a t s e e d l o s s f requen t l y occu rs du r ing w in te r . Loss may be due t o such obvious causes as r a i n w a s h i n g s e e d o f f t h e b e d , o r due t o less obv ious causes, poss ib ly fungal i n o r i g i n .

1.3 ( b ) Spr ing sowing.

Spr ing sowing i s c a r r i e d o u t w i t h s t r a t i f i e d seed. Sowing a t t h i s t i m e o f y e a r a v o i d s w i n t e r seed loss, and,

3.

w i f done early enough, can produce 1-0 seedlings as 'large as those obtained from fa1 1 sowing.

The importance of sowing as early as possible in the spring can n o t be over-emphasized. Every opportunity o f dry weather should be taken in March and Apri 1 t o prepare land for seedbeds in coastal nurseries and sowing should be completed by mid-May. A week or two gained in spring lias a disproportionately large effect on increasing seedling size by the end of the year because of the exponential nature of seedling growth. The effect of sowing date on seedl ing s ize was investigated a t Duncan (Table 1 ) .

Table 1 . 1-0 gouglas-fir shoot length and dry weight a t iluncan nursery on 15 October by sowing date.

Sowing date 10 Flarch 10 Apri 1 10 May 1 2 June

Shoot length (cm) 16 .4 14.7 12.4 7 .0

Total dry weight ( 9 ) 0.482 0.388 0.341 0.152

Root/shoot ratio (weight) 0.31 0.33 0.41 0.50

1 .4 Sowing density

au,

Increasing the number o f seedlings per unit area of nursery bed reduces , t h e s i z e of the seedlings produced. Seedling dry weight and stem diameter decrease as seedbed density increases regardless of whether broadcast or d r i l l sowing metilods are used. The number of plants obtained from a given quantity o f seed (plant per cent) also decreases as seedbed density increases. Seedling shoot length is least affected by sowing density. T h i s has been verified with Douglas-fir a t Duncan and Quinsam nurseries (Table 2 ) .

Growing less than 20 Douglas-fir seedlings per square foot results in "bushy" seedlings with strongly developed la teral branches. Tile ideal density for producing vigorous Douglas-fir i s 25-30 seedlings per square foot, depending on s o i l f e r t i l i t y and o t ; w nursery conditions. This i s equivalent t o 10-13 plants per foot o f d r i l l , assuming 7 d r i l l s a r e sown a long a 3.66 foot wide nursery bed. Hem1 ock should be grown a t the same density as Doug1 a s - f i r . The idzal density for spruce (c.f. Bel 1 , 1968) i s 30-35 seedl i ngs per square foot- (18-21 seedlings per foot of d r i l l ) and this density is probably suitable for lodgepole pine.

If larger numbers of plants are required prepare more beds. Do n o t increase seedling density since this reduces plant per cent and increases the number of cu l l s .

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Table 2. Relationship between seed bed density and growth of 1-0 Douglas- f i r a t two nurseries.

Sowing rate b o t h nurseries (9. dry seed/sq. f t . )

.121 ,363 .613 .855 1 . l o 6

Duncan nursery

Densi t y / sq . f t . 9 29 44 56 73

Plant % 68 75 67 61 62

Shoot length cm. 19.5 17 .4 17.3 18.2 17.9

Shoot dry weight g . 2.00 1 . 1 4 0.93 0.83 0.70 ~~ ~ ~~ ~~ ~ ~ ~ ~~~~~ ~ ~ - ~~~ ~ ~~~ ~ ~ ~ ~~ ~~~~ ~~ ~~

Qui nsam nursery

Dens i ty/sq. f t . 14 32 57 69 80

Plant % 99 81 87 76 68

Shoot length cm. 17.3 16.9 15.3 15.9 15.3

Shoot dry weight g. 1 .27 0.87 0.63 0.59 0.45

1 .5 Broadcast and dri 11 sowing

Broadcast sowing re l ies on ski l l for sat isfactory resul ts and i s mucil more dependent on ;land labour than dri 11 sowing. Dri 11 sowing can be carried o u t rapidly with suitable macilinery, and provicies even distribution o f seed. Clleeding of d r i l l sown beds is simplified because mechanized sprayers can be used between the rows, and lateral root pruning is also possibie. Dril l sowing i s recommended unless very small seed lots are t o be sown. At present 7 d r i l l s are sown 6 inciles a p a r t a1 ong beds which are 3 f t . 8 inches wide.

1.6 Depth o f sowing

Small seed, such as t h a t of spruce and hemlock , i s sown a t a depth of 1/8 t o 1 /4 inch. Larger seed, such as t h a t of pine and Bouglas f i r i s sown a t a depth of 1 / 4 incn.

1 . 7 Covering seed

Conifer seed must be covered wi ti1 f ine gri t , ideally consisting of particles w a b o u t 1/8 inch in diameter. Soil i s unsuitable for covering conifer seed. Tilis

5.

i s because seed damage b y p a r a s i t i c f u n g i seems t o be incret2sed by so i l cove r ing , p robab ly because o f poo r ven t i l a t i on . The g r i t , o r c o a r s e sand, used fo r cover ing must no t con ta in ca lc ium carbonate , and should have a n e u t r a l o r a c i d r e a c t i o n ( p t i 7 o r l e s s ) . I n n u r s e r i e s w i t h s u i t a b l e sandy s o i l i t i s p o s s i b l e t o c o v e r d r i l l s w i t h n u r s e r y s o i l .

1.8 Bed p r e p a r a t i o n

The ground t o be used f o r beds must haveany pan broken wi th a sub- s o i l i n g p l o u g h o r r i p p i n g t y n e . It i s then p loughed to a d e p t h o f 9 inches, and harrowed t o o b t a i n a f i n e t i l t h . The depth o f p lough ing must no t be reduced i n o r d e r t o speed the ope ra t i on , and ne i ther shou ld the work be done when t h e s o i l i s w e t so tha t pudd l i ng occu rs . S tones , roo ts , and o t h e r d e b r i s must be removed w i t h s u i t a b l e e q u i p m e n t ( e . g . r o o t r a k e ) , o r b y hand, a p r a c t i c e w h i c h i s f r e q u e n t l y n e c e s s a r y i n a new nursery .

Organ ic ma t te r , such as pea t , and s low ly so lub le f e r t i l i ze rs , no tab ly calc ium superphosphate, sulphur, and l imestone, are spread, if necessary, o v e r t h e s o i l a t t h i s s t a g e f o r i n c o r p o r a t i o n d u r i n g t h e f i n a l h a r r o w i n g .

The p r e p a r e d s o i l i s f o r m e d i n t o r a i s e d beds w i t h a t ractor-drawn bed- shaping sledge. Beds, 3 ft. 8 inches wide, are ra ised about 4 inches above the paths which are 24 inches wide. Rais ing the beds improves drainage dur ing the w i n t e r so t h a t f r o s t h e a v i n g i s reduced. The beds are compacted and leve l led b y r o l l i n g , u s u a l l y w i t h a r o l l e r drawn behind the bed shaper.

w Drill sowing equipment current ly used i n B r i t i s h Columbia Forest Serv ice

n u r s e r i e s i n c l u d e s a r o l l e r w i t h one i n c h t h i c k m e t a l hoops which form shal low fur rows. Seed i s a u t o m a t i c a l l y f e d i n t o t h e f u r r o w s as the equipment moves along, and i s i m m e d i a t e l y c o v e r e d w i t h c o v e r i n g g r i t , sand, o r bed s o i l (1 .7 ) . The d r i 11 must be c a l i b r a t e d f o r each seed l o t . T h i s i s done by r u n n i n g t h e m a c h i n e w i t h p l a s t i c bags o v e r t h e o u t l e t s u n t i l t h e c o r r e c t q u a n t i t y o f seed i s d e l i v e r e d o v e r a p a r t i c u l a r d i s t a n c e .

B roadcas t sow ing requ i res t ha t t he co r rec t amount o f seed i s weighed out f o r each 50 ft. l e n g t h o f bed i n p r e p a r a t i o n f o r s c a t t e r i n g by hand. When la rge a reas a re b roadcas t sown a g r i t c o v e r i n g i s mechanical ly spread across the whole bed from a t r a c t o r drawn c a r t . When small areas are sown t h e g r i t may a l s o be broadcast evenly over the seed by hand.

Side boards, 8 inches i n h e i g h t , a r e o n l y u s e d on hemlock beds i n c o a s t a l n u r s e r i e s . They p r o v i d e a convenient support for snow-fence shade f rames which must be used dur ing the f i r s t y e a r f o r s h a d i n g hemlock. Side boards may a l s o be necessary to support shade f rames used to reduce snow and f r o s t damage i n I n t e r i o r and n o r t h e r n n u r s e r i e s . Use o f s ide boa rds shou ld be avoided whenever poss ib le as they are expensive to ra ise, hamper use o f machinery, and appear t o have no b e n e f i c i a l e f f e c t on growth o f Douglas fir o r spruce i f i r r i g a t i o n i s adequate. Side boards, i f used, a r e n o r m a l l y i n s t a l l e d b e f o r e b r o a d c a s t s o w i n g , b u t a f t e r d r i l l s o w i n g .

2 . Ferti 1 i z a t i on

2.1 General

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Production of useable seedlings i s very dependent on judicious use of f e r t i l i z e r s . Tree seedlings tend t o deplete nursery soils o f nutrients rapidly because whole plants, including most of the roots, are removed from the nursery a t 1 i f t i ng . A1 1 the nutrients they have absorbed during the i r growth in the nursery are removed and nothing i s returned t o the soil as i t i s when, say, wheat stubble is ploughed in. The f e r t i l i z e r s which have t o be used with each rotation of nursery seedl ings are nitrogen (N) , phosphorus(P) , and potassium ( K ) . Calcium (Ca) and magnesium (Mg) may have t o be used occasion- a l ly , b u t t h e r e i s l i t t l e evidence t h a t any of the micronutrients, such as copper ( C u ) , zinc ( Z n ) , boron ( B ) , or manganese (Mn) are required in the nurseries a t present.

2 . 2 N

Nursery-grown Douglas f i r crops respond more t o N t h a t t o o ther fe r t i l i zers . Greater quantities of N f e r t i l i z e r can be applied with corresponding growth increase than P or K f e r t i 1 izers , which soon reach a 1 imi t above which further applications do n o t increase growth. L i t t l e response t o even N can be obtained in the f i r s t year , however, unless sowing i s done in the previous autumn or early i n spring (March and April) . Late spring (May) sown Douglas f i r seedlings are most efficiently nitrogen fert i l ized during the second year. Good response of a u t u m n , or early spring sown, seedl ings t o !.I f e r t i 1 izer resul ts from t o p dressing applied before mid-July of the f i r s t y e a r . I4 uptake and some growth response can be obtained by application of f e r t i l i z e r during the dormant period in October, or February and !,larch. Growth o f interior spruce i s improved by N fer t i l izat ion before la te August of the f i r s t year regardless of whether the stock i s f a l l - or spring-sown.

2 . 2 ( a ) Time of N application,

Time o f N application has a major e f fec t on growth response. For example, a unit quantity of N applied only in the second year t o fall-sown Douglas f i r produced slightly larger seedlings than the same amount applied only in the f i r s t year (Table 3 ) . April application consistently produced larger seedlings than June application, and treatment in April of f i r s t and second year produced seedl i ngs twice as large as those receiving no application.

2 . 2 ( b ) N source.

In an experiment in which different N sources were compared a t two nurseries no real advantage of urea, urea formaldehyde, ammonia or ammonium phosphate over ammonium sulphate or ammonium ni t ra te was noted. On the other hand ammonium sulphate frequently causes greater growth responses t h a n ammonium ni t ra te . This may be due t o ammonium sulphate having a greater acidifying effect on the soil , or because more ammonium n i t r a t e N i s leached from the soi 1 as a resu l t of h a l f being in the anionic form, or the seedlings may absorb ammonium N fas te r than n i t r a t e N.

7 .

U Table 3. Dry weight (grams) of f a l l sown Douglas f i r r e s u l t i n g from

different times of ammonium nitrate application. *

U

Time of second Time of f i r s t year application year appl i cat i on

No appl ication Apri 1 June

No application 4.74 6.33 5.20

Apri 1 6.78 10.71 7.66

June 6.68 6.48 6.10

* 40 and 80 lbs. N/ac application rates of original experiment have been averaged t o emphasize time effect .

Ammonium n i t r a t e should be used a t coastal nurseries unless the intention i s t o increase soil acidity. Seedling mortal i t y i s always less in Doug1 as f i r beds with ammoni um n i t r a t e than with ammonium sulphate. Tile advantage in spruce growth obtained with ammonium sulphate just i f ies i ts use in Interior nurseries unless soil pH i s below 4.

2.2(c) I4ethod of applying i 4 .

Top dressing with a soluble fer t i l izer is the simplest way of applying N . Two applications of 20 lbs N/ac are adequate for small 1-0 seedlings. Excessive use of N f e r t i l i z e r on 1-0 seedlings almost invariably accentuates damping-off. Two or three applications of 40 lbs N/ac a t three o r f o u r week intervals start ing in Apri 1 i s the most e f f ic ien t way of treating 2-0 seedlings and transplants. More than 80 1 bs N/ac should n o t be applied a t any one time. Irrigation of the crop a f t e r t o p dressing i s necessary in dry weather to avoid "burning" due to high f e r t i l i z e r s a l t concentration. Alternatively [.I may be applied through tile i r r igat ion system. The basic N f e r t i l i z e r schedule i s shown in Table 4.

2.3 P

P moves slowly in the soil and i s n o t readily leached. Furthermore calcium superphosphate fer t i l izers are re la t ively insoluble . I t i s important, therefore, t o work superphosphate into the soil t o a depth of a t l eas t 4 inches where i t wi 11 be available t o seed1 ing roots. This usual ly means

8.

Table 4. Top dressings of N for conifers i n British Columbia nurseries. U

Stock Time of Lbs N/acre Ferti 1 i ze r Lbs f e r t i 1 i zer Lbs f e r t i 1 i ze r appl i cation /acre 1183 sq.ft.bed

Doug1 as f i r and hemlock

Fall sown

1-0 ear ly June 20 ammoni um 60

, early July 20 (33-0-0) 60 n i t r a t e

0.25

0.25

S p r i n g sown k

( a ) good 1-0 0 0

( b ) poor 1-0 early July 20 60 0.25 II

2-0 and mid Apri 1 40 transplants

mid June 40

II 120

1 20

0.50

0.50

Interior spruce wu,

Fall and spring sown

1-0 early July 20 ammon i um 100 ( i f seed- sul phate l ings s u f - (20-0-0) f i c i en t ly advanced)

0.42

7 mid August 20 100 0.42 II

2-0 and ear ly June 21 mon- 190 transplants ammo n i um

phosphate ( 1 1-48-0)

l a t e June 20 ammon i um 100 sulphate (20-0-0)

0.80

0.42

mid July 40 200 0.84 II

i f necessary mid August 40 I1 200 0.84

9.

U

c

application before bed formation, b u t where d r i l l sowing i s done d r i l l i ng superphosphate below the seed would be the most e f f ic ien t procedure.

Significant growth responses t o P have only been obtained a t Koksilah nursery which had been pasture for many years before conversion t o a nursery (van den Driessche, 1969a) . Nursery stock removes considerable quanti t i e s of P from the soi 1 , however, and i t has been customary t o add P f e r t i l i z e r s so t h a t soi l P has been maintained a t an adequate level in the older nurseries. Continued application of P i s necessary t o ensure t h a t deficiencies do n o t develop.

2.3(a) P source.

P should be applied as calcium superphosphate (0-20-0) because th i s fe r t i l i zer , as so ld commercial ly , contains Ca (about 20%) and S ( a b o u t 12%) , as we1 1 as P ( a b o u t 8 .7%) . Triple superphosphate (0-45-0) should be used only i f soi 1 Ca i s known t o be high , or i f s o i 1 pH i s much too high. Triple superphosphate contains less Ca (about 13%) and less S ( a b o u t l % ) , b u t more P (about 19.5%) than calcium superphosphate.

Top dressings of P are usually unnecessary, except for Interior spruces which appear t o benefit from an application of monammonium phosphate (11-48-0) applied in April or May of the second year just after f lushing has commenced.

Application of 60 lbs P/ac i s adequate, with an extra 40 lbs P/ac for Interior spruce (Table 5), unless deficiency has been recogni zed.

Table 5. P fert i l izer applications for conifer nurseries in Brit ish Columbia.

Time of application Lbs P Ferti 1 i zer Lbs f e r t i l i z e r Lbs f e r t i l i z e r /acre /acre /183 sq. f t .bed

Work into soil 60 calcium superphosphate 690 2.9 before sowing 0-20-0

- or

Work i n t o soi l 60 t r i p l e superphosphate 306 before sowing 0-45-0

Top dressing for 40 monammonium phosphate 190 Interior spruce 11 -48-0 after f lushing i n second year

1.3

0.8

10.

2.4 K

Pos i t i ve g rowth responses o f con i fe r seed1 i n g s t o K f e r t i l i z e r have not been recorded i n c o a s t a l n u r s e r i e s , p r o b a b l y because t h e s o i I s c o n t a i n K supp ly ing m ine ra l s , and a l s o K f e r t i l i z a t i o n has prevented any dec l ine i n K leve l . There i s ev idence t ha t excess i ve K f e r t i l i z a t i o n c a n r e s u l t i n un- d e s i r a b l y h i g h s o i l K l e v e l s i n t h e s e n u r s e r i e s ( v a n den Driessche, 1963a). K d e f i c i e n c y does occur i n c o n i f e r n u r s e r i e s , however, and appears, for example, as a p u r p l i n g o f n e e d l e t i p s i n S i t k a s p r u c e , w h i c h changes t o ye1 low during the season (Benzian, 1965, p. 79-80).

2.4(a) K source.

K i s n o r m a l l y s u p p l i e d as e i t h e r p o t a s s i u m s u l p h a t e o r p o t a s s i u m c h l o r i d e f e r t i 1 i zer. Damage t o Norway spruce (Picea abies K a r s t . ) b y c h l o r i d e i n p o t a s s i u m c h l o r i d e has been repo r ted by Nemec (1 939) , and subsequent ly noted by Benzian (1 966). Potassium sulphate i s p robab ly a p r e f e r - a b l e s o u r c e o f K (about 44% K) and has the advantage o f a l s o s u p p l y i n g S (about 18%). No b e n e f i t o f t o p d r e s s i n g o v e r p r e - s o w i n g a p p l i c a t i o n o f K has been observed i n S i t k a s p r u c e seed beds (Benzian , 1965, p . 78-79).

2.4(b) Method o f a p p l y i n g K.

P o t a s s i u m s u l p h a t e f e r t i l i z e r s h o u l d b e w o r k e d i n t o t h e s o i 1 before sowing, and, where necessary, a f u r t h e r t o p dress ing app l ied dur ing the second year o f g rowth . Crops must be i r r i g a t e d a f t e r t o p d r e s s i n g i n d r y w e a t h e r as potassium s u l p h a t e i s a r e a d i l y s o l u b l e s a l t ( T a b l e 6 ) .

Tab le 6. K f e r t i l i z e r a p p l i c a t i o n s f o r c o n i f e r n u r s e r i e s i n B r i t i s h Columbia.

Time o f a p p l i c a t i o n Lbs K F e r t i 1 i zer Lbs f e r t i l i z e r Lbs f e r t i l i z e r /acre /acre 1183 sq. f t .bed

Work i n t o s o i l 40 potass ium su lphate 91 be fo re sow i ng l (0-0-53)

0.38

- o r

Work i n t o s o i l 40 po tass ium ch lo r i de 78 0.33 before sowing (0-0-62)

Top d r s s I n t e r i o r 40 potass ium su lphate 91 spruce? and trans- (0-0-53) p l a n t s a t f l u s h i n g i n second year

0.38

’ No a p p l i c a t i o n s h o u l d be made i f s o i l a n a l y s i s shows more than 0.45 m.e.q. K/100 g s o i l .

T h i s may a l s o b e n e c e s s a r y f o r o t h e r s p e c i e s i n n u r s e r i e s on sandy s o i l s .

11.

2.5 Ca w

H i g h l e v e l o f Ca i s u n d e s i r a b l e i n a c o n i f e r n u r s e r y s i n c e i t r a i s e s s o i 1 pH and promotes growth o f " d a m p i n g - o f f " f u n g i . Use o f ca l c ium super - phosphate should ensure an adequate supply o f Ca to t he c rop . A s i n g l e d r e s s i n g o f ground l imestone a t 2,000 l b s / a c r e s h o u l d b e w e l l w o r k e d i n t o t h e s o i l b e f o r e sowing on ly if s o i l a n a l y s i s shows less than 1 .0 m.e.q. Ca/100 g s o i l , o r 1 - 0 Douglas fir seed l i ngs con ta in l ess t han 0.1% Ca i n d r y t i s s u e .

2.6 Mg

A p p l i c a t i o n s o f Mg f e r t i l i z e r s t o Douglas fir seedl ings have not been found to inc rease seed l i ng s i z e w i t h o u t d r a s t i c a l l y r e d u c i n g seed bed densi ty (van den Dr iessche, 1963 a). There i s no ev idence that Mg f e r t i 1 i z e r s a re necessary fo r Doug las fir. By contrast , Si tka spruce has somet imes been found t o r e s p o n d t o Mg f e r t i l i z a t i o n ( F a u l k n e r and Aldhous , 1956). A symptom o f Mg d e f i c i e n c y i n S i t k a s p r u c e i s a b r i g h t y e l l o w d i s c o l o u r a t i o n o f t h e u p p e r p a r t o f t h e s e e d l i n g ( B e n z i a n , 1965, p. 86) .

So f a r Mg d e f i c i e n c i e s have n o t been i d e n t i f i e d i n S i t k a s p r u c e g r o w i n g i n c o a s t a l n u r s e r i e s . Mg can be a p p l i e d t o n u r s e r y s o i l , i f d e f i c i e n c y i s ever conf i rmed, by apply ing 100 lbs Mg/acre as magnesium sulphate. Magnesium su lphate may be o b t a i n e d i n a very hydra ted fo rm (Epsom s a l t s ) when 1,000 1 bs a r e r e q u i r e d t o o b t a i n 100 1 bs Mg , o r i n a 1 ess hyd ra ted f o rm (K iese r i t e ) when 500 l b s a r e r e q u i r e d t o o b t a i n 100 l b s Mg.

3. S o i l pH

3.1 General

S o i l pH has a l a r g e e f f e c t on growth o f many c o n i f e r s s i n c e i t a l t e r s a v a i l a b i l i t y of n u t r i e n t s and g r e a t l y i n f l u e n c e s t h e c o n s t i t u t i o n o f t h e s o i l m i c r o - f l o r a and fauna. The pH s c a l e i s used f o r m e a s u r i n g a c i d i t y and a l k a l i n i t y o f ac ids and bases . A pH o f 7 i n d i c a t e s a n e u t r a l r e a c t i o n , l o w e r v a l u e s i n d i c a t e a c i d i t y and h i g h e r v a l u e s a l k a l i n i t y . A s o i l o f pH 4, o r l e s s , i s cons ide red s t rong ly ac id , and a s o i l o f pH 7.5 o r above i s u s u a l l y c a l - careous , o r c o n t a i n s "a1 k a l i l ' .

Spruces, hemlock, and lodgepole p ine grow best on so i ls o f pH 4-5. Douglas fir seems more t o l e r a n t , g r o w i n g s a t i s f a c t o r i l y w i t h i n a pH range 4-6. Western red cedar and Ponderosa p i n e show b e s t g r o w t h a t a b o u t pH 6-7.

3.2 Changing s o i l pH

S o i l pH can usua l l y be ra i sed by t he add i t i on o f g round l imes tome o r s laked l ime (Ca(OH),) a p p l i e d a t a r a t e o f 1 t o 2 tons pe r ac re . The problem i n most coni fer nurser ies, however , i s t o r e d u c e s o i l pH. Ammonium su lphate and ammonium phosphate f e r t i 1 i z e r s t e n d t o r e d u c e s o i 1 pH, and su lphur ( S ) ,

12.

W

rrr

c

s u l p h u r i c a c i d (H2S04) , and a1 uminum sulphate (A12(S04) 3) are agents used s p e c i f i c a l l y f o r r e d u c i n g s o i l pH. Incorpora t ion o f hop-waste ( f rom b rewer ies) , o r p e a t , i n t o t h e s o i 1 usual l y reduces pH. T r e a t m e n t o f s o i 1 w i t h S, H2S04 , o r A12(S04)3 shou ld be car r ied ou t as long be fore sowing as poss ib le . The maximum r e d u c t i o n i n pH ach ieved w i th S does n o t o c c u r f o r s e v e r a l months a f t e r a p p l i c a t i o n and, i n t h e meantime, o x i d a t i o n p r o d u c t s t o x i c t o p l a n t s may be produced.

3.3 Examples o f pH changing t reatments

Hop-waste had most e f f e c t i n r e d u c i n g pH o f a ca lcareous s i l t loam a t t h e East Kootenay nursery. A 1 - i nch - th i ck d ress ing worked i n to t he so i l r educed pH 1.17 u n i t s a f t e r two years. A decrease i n pH o f 0.98 u n i t was o b t a i n e d w i t h commercial peat. The p o s s i b i l i t y o f r e d u c i n g s o i l pH w i t h i n o r g a n i c m a t e r i a l s was also examined a t t h i s n u r s e r y ( T a b l e 7 ) .

Table 7. Reduct ion i n pH o f c a l c a r e o u s s o i l a c h i e v e d w i t h i n o r g a n i c subs tances over four months at East Kootenay nursery.

T rea tmen t So i l pH va lues

Su lphur Apr i 1 June August

(1 bs/ac. ) (be fo re t rea tmen t )

2,000 8.10 7.52 7.36

4,000 8.10 7.50 7.27

8,000 8.12 7.32 7.02

S u l p h u r i c a c i d

(spec . g r . 1 .84 , l i t res /ac . )

500

1,000

2,000

Ammonium phosphate

(1 1-48-0, 1 bs/ac. )

71 0

1,420

Cont ro l

8.10

8.07

7.93

7.18

6.79

5.67

7.68

7.46

6.37

8.04 7.09 7.54

8.06 6.81 7.40

7.99 8.04 7.98

13.

U S u l p h u r a n d s l a k e d l i m e w e r e a p p l i e d t o s i l t l o a m s o i l s a t two coasta l

n u r s e r i e s i n s p r i n g t o o b t a i n p l o t s w i t h d i f f e r e n t s o i l pH. Douglas f ir sown d u r i n g t h e same s p r i n g showed 1 i t t l e a d v e r s e e f f e c t o f s u l p h u r t o x i c i t y . Sulphur a t 4,000 lbs/ac decreased pH by 1 u n i t i n June and about 1.4 uni ts i n September (Table 8) . Slaked l ime at 4,000 lbs /ac i nc reased pH by about 1.1 u n i t s i n June, bu t on ly by 1 .O u n i t i n September. All p l o t s had become s l i g h t l y more acid between June and September, probably due t o f r e q u e n t n i t r o g e n t o p d r e s s i n g . Between September and June o f t h e f o l l o w i n g y e a r treatments had no f u r t h e r m a j o r a f f e c t on s o i l pH.

S u l p h u r a p p l i c a t i o n s o f more than 1,500 l b s / a c t o O n t a r i o n u r s e r i e s r e d u c e d s u r v i v a l o f Red pine, though average seedl ing dry weight increased up t o a t l e a s t 2,250 l b s o f s u l p h u r p e r a c r e ( M u l l i n , 1 9 6 9 ) .

No " fa rmyard manure'' o r " s t a b l e manure" o f any s o r t may be used i n c o n i f e r n u r s e r i e s because i t r a i s e s s o i l pH , and , a l m o s t i n v a r i a b l y , r e s u l t s i n damping-of f epidemics.

Table 8. Average changes o f s o i 1 pH obta ined w i th su lphur and s laked 1 ime a t two coas ta l nurser ies .

S o i l pH Trea tmen t App l i ca t i on Year 1 Year 2

(1 bs /ac) June September June

C o n t r o l 0 5.57 5.38 5.45

Sulphur 1,500 4.88 4.48 4.74

Sulphur 4,000 4.54 4.00 3.91

Lime 1,500 6.29 5.88 5.88

Lime 4,000 6.65 6.33 6.29

4. Organ ic mat te r

4.1 General

Organic amendments a r e n o r m a l l y c o n s i d e r e d t o i n c r e a s e y i e l d s on a g r i - c u l t u r a l s o i l s . I n c o r p o r a t i o n o f o r g a n i c m a t t e r i n s o i l u s u a l l y i n c r e a s e s aggrega te s tab i 1 i ty and c a t i o n exchange capacity, and may i n c r e a s e a v a i l a b i 1 i ty o f v a r i o u s n u t r i e n t s as t he o rgan ic ma t te r decomposes. Nurse ry so i l s shou ld c o n t a i n 5 8 % o r g a n i c m a t t e r ( d r y w e i g h t b a s i s ) . H i g h e r l e v e l s a r e n o t known t o be a d i s a d v a n t a g e , b u t a r e h a r d t o a c h i e v e i n p r a c t i c e . The organ ic m a t t e r l e v e l has t o be r e p l e n i s h e d p e r i o d i c a l l y due to con t i nua l decompos i t i on .

14.

4 .2 Su i tab le o rgan ic amendments

Probab ly the most su i tab le amendment i s b a l e d h o r t i c u l t u r a l p e a t . P e a t f r o m l o c a l p i t s may be as good i f i t i s f i r s t de te rm ined to be m a i n l y o r g a n i c matter, and i s n o t c o m p l e t e l y decomposed t o "muck". Hop-waste i s a good o r g a n i c amendment i f obta inab le .

4.3 Sawdust

Sma l l quan t i t i es o f sawdus t a re added t o seedbeds once each r o t a t i o n t o p r e v e n t f r o s t - h e a v i n g o f 1 - 0 s e e d l i n g s . S e e d l i n g s i n beds which, f o r some

and more vigorous i n March , un less severe ly a f fec ted by f ros t -heav ing . It i s we1 1 known t h a t a d d i t i o n o f sawdust o r wood c h i p s t o s o i 1 r e s u l t s i n l a c k of

of sawdust i n w i n t e r c o u l d have much a f f e c t on n i t r o g e n n u t r i t i o n o f d o r m a n t seed l ings . It seems q u i t e p o s s i b l e , t h e r e f o r e , t h a t m i l d l y t o x i c s u b s t a n c e s are leached f rom the sawdust dur ing the winter. Western red cedar sawdust i s known to p roduce subs tances t ox i c t o seed1 ings (Kreuger, 1963). Consequent ly, though i t may be necessary to use sawdust mulch because i t i s cheap, sawdust i s n o t recommended as an organ ic amendment.

-.I reason, do no t rece ive the sawdust mu lch in October o f ten appear g reener

11 a v a i l a b l e n i t r o g e n . It would be surpr is ing, however, i f a s u r f a c e a p p l i c a t i o n

Decomposi t ion of sawdust i s m o s t r a p i d i n a s o i l o f pH 7 and becomes p r o g r e s s i v e l y s l o w e r w i t h i n c r e a s e i n a c i d i t y . A minimum o f 25 l b s N p e r t o n o f d r y sawdust must be added t o o f f s e t n i t r o g e n r e n d e r e d u n a v a i l a b l e d u r i ng decomposi ti on (A1 1 i son, 1965).

4.4 Unsui tab1 e o r g a n i c amendments

Farmyard manure i s u n s u i t a b l e as an o r g a n i c amendment f o r c o n i f e r n u r s e r i e s due t o i t s h i g h pH and weed seed content (see 3 .3) . Seaweed has been found an u n s a t i s f a c t o r y amendment i n B r i t a i n , p r o b a b l y because o f i t s sod ium ch lo r ide con ten t (2%) (A ldhous , 1968) .

c

5. R o t a t i on

U

5.1 General

Crop r o t a t i o n has l o n g been used i n a g r i c u l t u r e as a method o f m a i n t a i n - i n g s o i l f e r t i l i t y and c o n t r o l l i n g c r o p d i s e a s e s . Y i e l d i n c r e a s e s i n c e r e a l s can be ob ta ined , w i thou t i nc reas ing f e r t i l i ze r t rea tmen ts , i f s u i t a b l e c r o p r o t a t i o n s a r e used which reduce incidence o f fungal diseases (Jacks 1954, p.62). Legumes, p a r t i c u l z r l y c l o v e r , a r e u s u a l l y recommended i n a g r i c u l t u r a l p r a c t i c e as t h e " s o i 1 c o n d i t i o n i n g " c r o p t o be used i n a r o t a t i o n , l a r g e l y because o f t h e i r N f i x i n g a b i 1 i ty. Grass c;"ps a r e a1 so recommended because they i n c r e a s e s o i l a g g r e g a t i o n a n d i m p r o v e s o i l w o r k i n g c h a r a c t e r i s t i c s .

5.2 R o t a t i o n i n c o n i f e r n u r s e r i e s

I n c o n i f e r n u r s e r i e s t h e m a i n v a l u e s o f a r o t a t i o n a r e ( 1 ) d i s e a s e c o n t r o l and ( 2 ) weed c o n t r o l . T h i s a l o n e makes a r o t a t i o n s t r o n g l y a d v i s a b l e .

15.

U

Improved seedl ing growth usual ly occurs on land "green-cropped" the previous year (e.g. Aldhous 1968), and i t i s n o t c l e a r l y due t o t h e m a n u r i n g e f f e c t o f p loughed- in green crop.

I d e a l l y a green crop should be grown and ploughed under after land has been i n seedbeds f o r two years. This may n o t b e p o s s i b l e i f space i s s h o r t , b u t a green crop should be grown af ter land has been four years i n seedbeds. Cereals, such as o a t s o r r y e , make sa t is fac to ry g reen c rops . Oats may be sown i n s p r i n g a t 2.5 t o 3 bushe ls pe r ac re , I n Eu rope b lue l up ins and po ta toes a r e f r e q u e n t l y u s e d i n c o n i f e r n u r s e r y r o t a t i o n s .

t h e be d weed l i k e

6.1

f r e e beds

F o r c o n t r o l 1 i n g weeds i t may be b e t t e r t o grow no green crop, but f a 1 low l a n d a n d i r r i g a t e i t t o cause the weed seed t o g e r m i n a t e . It can then isc -har rowed, o r sprayed w i th paraquat weed k i 1 l e r (6.3) so t h a t t h e

p o p u l a t i o n i s r e d u c e d . It must be emphasized t h a t t h i s p r o c e d u r e i s l y t o b e i n e f f e c t u a l i f no i r r i g a t i o n i s p r o v i d e d d u r i n g t h e summer.

6. Weed c o n t r o l

General

Clean pract ices and constant v ig i lance are necessary to keep nurser ies o f weeds. Paths, roads and surrounds should be kept weed f r e e . When a r e weeded the weeds must no t be a l lowed to l i e i n p a t h s o r roadways

fo r severa l days where they f requent ly shed seed, o r roo t aga in . Weeding must be car r ied ou t be fore the weedsset seed. Care must be t a k e n n o t t o i n t r o d u c e weed seeds i n t o t h e n u r s e r y . O r g a n i c m a t t e r , c o v e r i n g g r i t ( o r sand) and, o f course, so i 1 may c o n t a i n weed seeds , and should not be used if ser ious ly con taminated .

A r o t a t i o n w h i c h i n c l u d e s a yea r under g reen c rop o r f a l l ow , t ends t o reduce weed g r o w t h . C u l t i v a t i o n o f a f a l l o w a r e a a t m o n t h l y i n t e r v a l s d u r i n g the growing season i s necessa ry t o des t roy weeds. Much weed seed does n o t germinate on a fallow area unless it is irrigated. To get maximum weed c o n t r o l f r o m a f a l l o w y e a r i t i s n e c e s s a r y , t h e r e f o r e , t o i r r i g a t e o c c a s i o n - a l l y as we l l as c u l t i v a t e .

Hand weed ing con t inua l l y becomes more expensive, and every e f f o r t must be made t o r e d u c e i t t o a minimum by mechanical and chemical methods o f weed c o n t r o l .

6.2 Emergence s p r a y i n g

A t emergence, wh i l e seed coa ts a re s t i l l on t he young ge rm inan ts , beds should be "broadcast" sprayed wi th "She1 1 I' A g r i c u l t u r a l Weed K i 1 l e r (AWK) No. 1 s p e c i a l a t t h e r a t e o f 1 qua r t pe r bed (240 q u a r t s p e r a c r e o f b e d ) . AWK can be used on t r a n s p l a n t s a t t h e same r a t e . It i s n o t e f f e c t i v e a g a i n s t a1 1 weeds. For example, groundsel (Senecio sp. ) seems q u i t e r e s i s t a n t t o i t , and, once germinated, shepherds purse (Capsella bursa-pastoris) i s seldom compl e t e l y k i 11 ed.

Spruce and hemlock seedl ings are severely damaged by AWK i f spray ing i s

16.

U l e f t u n t i l s e e d c o a t s s t a r t t o f a l l o f f . Douglas fir i s much l e s s l i k e l y t o be damaged b y l a t e s p r a y i n g . Weed k i l l appears t o be more e f f e c t i v e if s p r a y i n g i s c a r r i e d o u t when h u m i d i t y i s h igh .

6.3 Seed bed spray ing

The b i p y r i d a l s a l t s " D i q u a t " ( d i b r o m i d e ) and "Paraquat " (d ich lo r ide) a re ve ry use fu l he rb i c ides (Boon, 1967). They de f lec t the normal photo- syn the t i c p rocess so t h a t a tox i c subs tance i s manu fac tu red by t he p lan t i t s e l f . The a c t i o n i s c a t a l y t i c so t h a t r e l a t i v e l y s m a l l amounts a r e e f f e c t i v e , b u t c h l o r o p h y l l , l i g h t , and oxygen must be present t o o b t a i n any r e s u l t . D i q u a t and Pa raqua t a re immed ia te l y i nac t i va ted i n t he so i l , and a re subsequent ly broken down b y l i g h t o r s o i l o r g a n i s m s . C o n s e q u e n t l y damage t o r o o t s does no t occu r .

Paraquat i s s u i t a b l e f o r weeding t ransplants and d r i l l sown seed l ings i f guards , mounted on the spray equ ipment , sa t i s fac to r i l y p ro tec t the c rop . Very small amounts o f sp ray can do severe damage t o t h e c r o p so t h a t appl icat ion between rows must be done carefu l ly . Paraquat , obta ined i n so lu t i on under t he t rade name "Gramoxone", has been s u c c e s s f u l l y u s e d t o weed seedbeds sprayed a t t h e r a t e o f 4 1 bs per acre ( 2 q u a r t s Gramoxone pe r ac re ) . The Gramoxone i s d i l u t e d w i t h w a t e r t o o b t a i n a s u i t a b l e volume f o r s p r a y i n g .

6 .4 Transp l an t spray i ng

Simazine i s one o f a group o f s i m i l a r h e r b i c i d e s ( t r i a z i n e compounds) , and has been e x t e n s i v e l y u s e d i n t r a n s p l a n t l i n e s i n c o n i f e r n u r s e r i e s . It i s r e l a t i v e l y i m m o b i l e i n t h e s o i l and rema ins ac t i ve f o r seve ra l mon ths . A f t e r a b s o r b t i o n t h r o u g h t h e r o o t s i t i n t e r f e r e s w i t h c h l o r o p h y l l f o r m a t i o n eventua l l y caus ing death . It does n o t e n t e r c o n i f e r s t h r o u g h t h e f o l i a g e (Kozlowski and Kuntz, 1963). Simazine can be used on crops, such as conifer t ransp lan ts wh ich have t he i r roo ts we1 1 be l ow the sur face and wh ich a re i n i t i a l l y f a i r l y weed f r e e , The h e r b i c i d e i s " b r o a d c a s t " s p r a y e d o v e r t h e c rop , bu t , due to s low movement i n t h e s o i l , r e m a i n s i n t h e t o p 2 or 3 inches and does n o t g e t t a k e n up by the crop. Weeds g e r m i n a t i n g i n t h e s u r f a c e s o i l , however, take up su f f i c i en t s imaz ine t o cause dea th . Sp rayed a t a r a t e o f 2 I b s ( a c t i v e i n g r e d i e n t ) p e r a c r e i t e f f e c t i v e l y c o n t r o l s weeds f o r 3 o r more months, It i s normal ly made up as 4 l b s 50% w e t t a b l e powder i n 40-60 gals water. The mix tu re must be a g i t a t e d because t h e powder forms a suspension which will s e t t l e o u t .

Simazine i s n o t v e r y e f f e c t i v e a g a i n s t l a r g e weeds a t t h e r a t e s a f e f o r c o n i f e r s . To g e t maximum b e n e f i t f r o m s p r a y i n g t h e a r e a t o be t r e a t e d s h o u l d f i r s t be weeded mechan ica l l y o r by hand.

There has been concern that s imazine accumulates i n t h e s o i l e v e n t u a l l y making i t c o m p l e t e l y s t e r i l e . A t e s t showed less t han 1 l b o f Simazine had accumulated i n sand and sandy loam nursery so i ls a f ter three consecut ive a n n u a l a p p l i c a t i o n s o f 8 lbs s imazine (A ldhous, 1966) . I f no more than 2 lbs s imaz ine per acre a re used i t seems t h a t t h e amount accumulating wou ld be neg l i g ib le .

17.

rrr

u

A t r a z i n e i s a n o t h e r t r i a z i n e h e r b i c i d e w h i c h s h o u l d be used i n t h e same general way as s imazine, Rates o f appl ica- t ion ment ioned i n t h e l i t e r a t u r e vary, however, from 3 t o 6 l b s o f a c t i v e i n g r e d i e n t p e r a c r e . A r a t e of 6 l b s a t r a z i n e ( a c t i v e i n g r e d i e n t ) p e r a c r e has been found most sat isfactory f o r weed c o n t r o l i n t w y e a r o l d Douglas fir a t Mesachie Lake nursery (Schmidt, R.L. , personal communication). I n t h i s case t rea tment w i th a t raz ine has a l w a y s b e e n f o l l o w e d b y t h o r o u g h i r r i g a t i o n t o wash t h e h e r b i c i d e o f f t h e Douglas fir f o l i a g e .

A t r a z i n e was f o u n d t o be more t o x i c t o y o u n g Red p ine seed l ings than s imaz ine (Kozlowski and Torr ie , 1965) .

There i s e v i d e n c e o f i n t e r a c t i o n between N n u t r i t i o n and uptake of t r i a z i n e he rb i c ides . Resu l t s ob ta ined w i th t omato (M insha l l , 1969) sugges t t ha t N f e r t i l i z a t i o n , p a r t i c u l a r l y w i t h ammonium compounds, may i n c r e a s e p l a n t u p t a k e o f t r i a z i n e compounds. On t h e o t h e r hand, g r o w t h s t i m u l a t i o n o f b o t h s l a s h and 1 o b l o l l y p i ne seed1 i ngs grown i n a c o n t r o l l e d e n v i r o n m e n t , was ob ta ined w i th l ow concen t ra t i ons (non -phy to tox i c ) o f s imaz ine and a t r a z i n e . F o l i a r N c o n c e n t r a t i o n was increased by as much as 24% by 0.8 p.p.m. s imazine i n t h e n u t r i e n t s o l u t i o n (Conner and White, 1968).

7. S o i l s t e r i l i z a t i o n

7.1 General

S o i l s t e r i l i z a t i o n (somet imes ca l led " fumigat ion" ) has been c a r r i e d o u t i n c o n i f e r n u r s e r i e s i n many p a r t s o f t h e w o r l d . S u b s t a n t i a l g r o w t h i n c r e a s e s a r e o b t a i n e d f o l l o w i n g a p p l i c a t i o n o f some c h e m i c a l s t e r i l a n t s . The o r i g i n a l r e a s o n f o r u s i n g s t e r i l a n t s was to e l im ina te p lan t pa thogens such as nema- t o d e s o r f u n g i , b u t t h e r e i s c o n s i d e r a b l e e v i d e n c e (Warcup 1957, Will 1962, Ingestad and Ni lsson, 1964) suggest ing that much o f t h e e f f e c t i v e n e s s o f s t e r i l a n t s i s due t o t h e i r r e n d e r i n g n u t r i e n t s a v a i l a b l e . I n p a r t i c u l a r many c h e m i c a l s t e r i l a n t s a r e c o n s i d e r e d t o i n h i b i t n i t r i f i c a t i o n so t h a t h i g h l e v e l s o f ammonium N occur i n t h e s o i l . A t l e a s t p a r t o f t h e response has been a t t r i b u t e d t o t h i s e f f e c t . C e r t a i n l y e x p e r i m e n t s have shown t h a t t h e c o n c e n t r a t i o n o f v a r i o u s m i n e r a l n u t r i e n t s , such as N, K, Cay and Mn, a r e

I f r e q u e n t l y h i g h e r i n p l a n t s grown on s t e r i l i z e d s o i l t h a n i n p l a n t s grown on un t rea ted so i 1 .

Frequent use o f t h e same s t e r i l a n t may a l l o w e s t a b l i s h m e n t o f r e s i s t a n t pathogens (Vaarta j a , 1964).

S t e r i l a n t s can damage seed o f c r o p s sown t o o soon a f t e r t r e a t m e n t . It i s e s s e n t i a l t h a t s t e r i l a n t s s h o u l d b e a l l o w e d t o d i s s i p a t e b e f o r e s o w i n g . Absence o f s t e r i l a n t s can be checked by germinat ing c ress (o r o ther rap id ly germinating seed) on samples o f t r e a t e d s o i 1.

7.2 Formaldehyde

T h i s i s e s s e n t i a l l y a f u n g i c i d e . I t i s normal ly ob ta ined as " f o r m a l i n " , an aqueous s o l u t i o n c o n t a i n i n g a b o u t 27% formaldehyde. This may be app l i ed a t a r a t e o f 7 0 g a l p e r a c r e a f t e r d i l u t i o n i n t h e r a t i o , 3 gal formaldehyde t o 700 g a l w a t e r . A p p l i c a t i o n r a t e s o f 155 gal formaldehyde per acre and h i g h e r a r e e f f e c t i v e b u t e x p e n s i v e . The l a r g e volumes o f s o l u t i o n make i t a r a t h e r i m p r a c t i c a l t r e a t m e n t e x c e p t f o r p a r t i c u l a r p u r p o s e s , s u c h as

18.

reducing damping-off organisms before sowing special seed.

7.3 Chloropicrin

This substance, commonly known f o r i t s use as " tear gas" , i s an effective fungicide, has nematocidal properties, and reduces weed growth. Douglas f i r responds well on soi ls t reated with chloropicrin (Will 1962, Thulin e t aZ. 1958, van den Driessche 1963, 1968). 3 ml may be injected t o a depth of 6 inches, a t 12 inch x 1 2 inch spacing, or i t may be chiselled into the soil a t a ra te of 300 lb (34 gal ) per acre. Chloropicrin applied a t 17 gal per acre in two coastal nurseries markedly improved growth of Dou l a s f i r , and 8 gal per acre caused some response (van den Driessche, 1963bq.

Both so i l temperature and moisture content influence the effectiveness of chloropicrin. Soil moisture conJent of 1-15% i s optimum a n d , though high soi 1 temperatures are desirable (68 F) , satisfactory results have been obtained with soi 1 temperatures varying from 360 F to 68O F (e . g . Benzian, 1965, p. 1 5 2 ) .

Chloropicrin deteriorates with storage and good resul ts can only be obtained with fresh material.

7.4 "Vorl ex"

This i s a commercial preparation containing a number of substances including methyl isothiocyanate and 1 , 3-dichloropropene, I t i s claimed t o be effective against soil fungi, nematodes, weeds, and soil insects. I t can be applied effectively when soil temperature i s as low as 40° F, b u t achieves results more rapidly a t soil temperatures of a b o u t 60° F. Application rates of 12-20 gal per acre will control nematodes, b u t 40-80 gal per acre may be necessary t o control fungi and weeds. The higher rates of treatment may be necessary t o obtain control on heavy (clay) so i l s . A t low so i l temperatures soi l should not be disturbed for three weeks after treatment, b u t a t higher soil temperatures i t may only be necessary t o allow one week t o elapse before disturbance. After the sterilant has remained undisturbed i n the soil it must be allowed to escape by adequate cult ivation. This i s particularly important i f the s o i l i s wet as water tends to prevent dispersal of the s ter i lant .

7 . 5 Root disease

Methyl bromide and mylone were found effective for control 1 ing Douglas f i r seedling root disease i n a coastal nursery (Bloomberg, 1965). These s ter i lants great ly reduced the soil fun,gal population, including the population of Fusarium oxyspomun which may have been implicated in the disease. On the other hand vapam, CIPC, and simazine were relat ively ineffective in reducing the disease or destroying fungi.

8. Irrigation

8.1 General

The quantity and frequency of irrigation supplied t o nursery seedlings has a major e f fec t on their survival and growth. I t i s

19.

w essential t o maintain seedbeds moist to the surface since germinating conifer seed1 i ngs have very smal 1 roots. Frequent i r r iga t ion i s necessary t o achieve th i s . Of the three conifers commonly raised in coastal nurseries, Douglas f i r seedlings are apparently the most drought-resistant. This i s probably because they are larger and develop an adequate r o o t system more quickly. Sitka spruce seems particularly susceptible t o low water supply during germination, b u t usually remains healthy i n soi l t oo wet for Douglas- f i r and hemlock.

Normally the necessity for irrigation in the nurseries is determined by the appearance of the seedbeds, and experience gained previously. Further- more, no irrigation schedule, or moisture measuring equipment now available i s l i ke ly t o completely replace the nurseryman's regular observations and in te l l igent use of i r r igat ion equipment.

So f a r the water budget method has unfortunately been found unsatisfactory for regulating irrigation. Water budgets are successfully used in agriculture and orchard practice where estimated deficits can be replen- ished by heavy watering a t re la t ively long intervals. They are probably inapplicable t o f i r s t year nursery seedbeds because quite small moisture changes in the t o p few inches of soi 1 , c r i t i ca l t o germinating conifer seedlings, are largely ignored. Guidance i n determining when i r r iga t ion i s required i s b e t t e r obtained from soil moisture measuring equipment. Tensiometers are only reliable up t o a tension of 0.85 bar (permanent wilting point is a b o u t 15 bars) , and are unsatisfactory a t depths of less t h a n 6 inches. Consequently only electr ical (Bouyoucos) resistance blocks are l ikely t o be sat isfactory for use in nurseries. I t must be remembered, however, t h a t even these may show low resistances due t o presence of f e r t i 1 izer sal ts as well as because of h i g h soil moisture. The relationship between moisture block resistance and soil moisture per cent has been worked out for a silt-loam nursery soil (Fig. 1 ) .

8.2 Soil moisture blocks

To use soil moisture blocks as a guide t o i r r igat ion requirements i t i s recommended t h a t 6 blocks per acre a re i n s t a l l e d f o r the g r o w i n g season. They should be placed f l a t a t a depth of exactly 3 inches in 1-0 beds, and a t a depth of 6 inches in 2-0 beds. The leads are attached t o a readily seen peg which i s shor t enough for the tractor t o pass over. Both block and peg must be placed in the same seedl ing dr i l l i n 2-0 beds so t h a t la teral roo t p r u n i n g does n o t damage them. The undercutting blade should pass below the block and peg.

Resistance (nowadays most instruments measure impedance, which i s a . c . resistance) of blocks should be measured 3 times per week a n d averaged for the irr igation unit . Average resistance must not exceed 6 K ohms ( 1 5-1 7%) in 1-0 beds on a s i l t loam. Resistances in the region of 2 t o 4 K ohms probably indicate soil moisture levels suitable for r ap id growth. Soil moisture levels indicated by resistances above 6 K ohms are tolerated by 2-0 seedlings, b u t growth i s r e s t r i c t ed .

8.3 Amount of i r r igat ion

"Rainbird" rotating sprinklers, used for i r r igat ing nurser ies , are said

4

Q) F1- 0 II L

W

* *

cu 0 J Q m z w - a 3 f -

W

3 (3

a

G

21.

ur,

t o deliver an average of 0.1 inch water per hour a t a spacing of 30 f t by 40 f t , and operating a t 50 lbs per sq inch. Rain gauge catches show, however, t h a t water reaches the soil surface a t a ra te of only 0.075 inches on average during the summer. The difference is probably mainly due t o evaporation.

Average soi l moisture deficit figures (Table 9 ) indicate t h a t as much as 4 inches of water may have t o be supplied t o a nursery soil during a mon th i n summer. A t a ra te of 0.075 inches per hour this will take almost 7 8-hour working days.

Table 9. Average soil moisture deficit a t five nurseries in inches of water.

Month Nursery Campbell Green Red

Duncan Cowichan River Timbers Rock

May 0.36 0 0.10 0 0.25

June 2.81 0.32 2.01 0.59 1.37

July 3.86 3.12 3.15 3.06 2.02

Aug 2.99 3.32 2.15 2.38 0.71

SeP 1.20 0 0.21 0 0.31

8.4 Cooling by i r r igat ion

Irrigation of recently germinated seedlings i s often carried o u t t o reduce temperature d u r i n g the hottest p a r t of the day. Reduction of temperature i s unnecessary for seedlings t h a t are more t h a n one year old so t h a t i t i s more economical t o irrigate older seedlings during a cool par t o f the day, or d u r i n g the night.

8.5 Frost protection by i r r igat ion

Irr igat ion of non-hardy seedlings will prevent them being damaged by f ros t . Under coastal conditions frosts may occur before 1-0 seedl i ngs have stopped growing, or developed any frost-hardiness. If they are sprayed with water as soon as f rost commences (i .e. as soon as the tempera- t u re f a l l s t o 32O F ) no damage occurs even t h o u g h the plants become we1 1 coated w i t h ice. Apparently the latent heat released as the water freezes prevents the temperature of the plants dropping much below 32O F. The method i s successful i f

1 . The f r o s t i s not so severe i t freezes the irrigation pipes.

2. I r r iga t ion i s continued until all ice has melted off seedlings. (Severe damage t o seedl i ngs has occurred when the i r r iga t ion i s turned on a f t e r a f ros t has been in progress for some hours.) To obtain frost protection by sprinkling irrigation lines should be l e f t in position on f i r s t year seed beds d u r i n g winter, b u t they must be drained during mid-winter t o prevent ice bursting them.

22.

9. Growth periodicity and root/shoot r a t i o

9.1 General W

I t i s important t o know when shoots and roots are active and when quiescent so t h a t cultural operations, such as roo t p r u n i n g , 1 i f t i n g , e tc . , can be correctly timed. Shoots and roots do n o t grow a t equal rates th roughou t the year so t h a t root/shoot ratio varies w i t h season. Undeserved attention is frequently focused on root/shoot ratios i n assessing stock quality due t o n o t rea l iz ing tha t th i s ra t io i s par t ly determined by the time of observation. To o b t a i n information on shoot and roo t growth one- year-old seedlings ( a t 1 f t x 1 f t spacing) were measured for a year a t two coastal nurseries.

9 . 2 Length of growing period

Perhaps the most s t r iking feature of the annual course of seedling growth, revealed by this study ( F i g . 2 ) , i s t h a t a b o u t h a l f the annual g a i n i n dry weight occurs af ter the beginning of September, when height growth has ceased. This gain i n dry weight probably consists of increase in stem diameter (Krueger and Trappe, 1967) and accumulation of food reserves ( W i n j u m , 1963). I n coastal nurseries a t least , conifers c lear ly make considerable growth d u r i n g the fal l af ter height has stopped increas- i n g .

U 9.3 Shoot and r o o t growth

Roots of one-year-old Douglas f i r start elongating i n March, and hemlock roots frequently start growth i n February. Root growth then slows as shoot weight s t a r t s t o increase in May and June. Root growth increases as shoot growth decreases a t the end of June, b u t becomes quiescent a g a i n towards the end of July and during August. This may n o t always be true as the time when different provenances show roo t ac t iv i ty and quiescence d u r i n g the summer may vary. Douglas f i r of one provenance showed maximum r o o t ac t iv i ty i n la te July and August, and a second provenance showed maximum root act ivi ty i n June and July in an Oregon nursery (Krueger and Trappe, 1967) .

Shoot growth gradual ly decreases i n r a t e d u r i n g October and November. In September vigorous r o o t ac t iv i ty re-commences. This commonly occurs a b o u t mid-September and may be related t o cooler weather and more favourable moisture conditions which prevail a t th is time of year. I t ceases a g a i n i n early November.

One-year-old S i t k a spruce seedlings show a similar seasonal pattern of growth t o Douglas f i r , except t h a t shoot growth starts sooner, and early spring r o o t act ivi ty is cur ta i led by the end of March. White spruce, i n this case growing ou ts ide i t s na tura l climatic environment, commences shoot growth a t the end of March, cutting root growth short a t the same time. Shoot growth slows during June, and r o o t growth proceeds rapidly u n t i l October, w i t h an inactive period d u r i n g July and early August.

- NEEDLE DRY WEIGHT -&- STEM DRY WEIGHT ")t R O O T D R Y W E I G H T

W

W

"- N E E D L E / T O T A L W E I G H T R A T I O

DOUGLAS FIR

0 /I

I 1 I 1

/d '\ X 0

0' I

,' I I

I

Id '\""- ""

I I I I I I I I I I I I I

*" 1 HEMLOCK

-0- R O O T / S H O O T W E I G H T R A T I O

SITKA SPRUCE

0

" _ -

o'6 1 WHITE SPRUCE /+"-

:::] 0.7

M O N T H

FIGURE 2 . ANNUAL COURSE OF DRY WEIGHT GROWTH OF FOUR SPECIES O F

CONIFER DURING THEIR SECOND YEAR

24.

9 .4 Rootlshoot r a t i o

U

..

I t has been suggested t h a t shoot growth a1 ternates with roo t growth in young Douglas f i r p l an t s because insuff ic ient substrata is produced t o permit simultaneous growth of bo th organs (Kreuger and Trappe , 1967). Observations on several species of mature trees (Romberger, 1963, p . 166) suggest t h a t root growth slows, or ceases, in winter when soil temperature is l imit ing, and slows or ceases in July and Augus t when soil moisture i s limiting. I n any case i t i s c l e a r t h a t root/shoot ratio will vary during the year, and t h a t the later plants are 1 ifted during the fa1 1 , or spring until bud break, the greater their root/shoot r a t i o will be. Consideration of available l i terature led Jones (1968) t o confirm t h a t root/shoot ratio decreases from the f i r s t y e a r onwards, and t h a t the root/shoot ratio of t ransplants is higher t h a n t h a t of seedlings of the same age.

Ferti 1 i z a t i o n , particularly w i t h nitrogen , i s usual ly found t o decrease the rootlshoot ratio of nursery seedlings (e.g. Aldrich-Blake, 1932). I t i s frequently assumed t h a t t h i s i s en t i r e ly due t o the fer t i 1 izer having a d i rec t e f fec t on root/shoot ratio, Even t h o u g h ni t rogen fer t i l izer may promote shoot growth re la t ively more t h a n roo t growth i t also increases the s ize o f the entire p l a n t , and 1 arger plants tend t o have smal le r root / shoot ratios. For example, a t Duncan nursery longer growth periods produced Douglas f i r seedlings of greater dry weight and smaller root/shoot ratio (Table 1 , Section 1.3).

Evidently any fer t i l izer t reatment which increases seedling size is l ikely to reduce root/shoot ratio, and i t i s probably fut i le to search for a f e r t i l i z e r which provides b o t h larger plants and greater root/shoot ra t ios . In any case root/shoot ratio is influenced more by the physical nature of the soil t h a n b.y nutrients. Root development i s more plentiful in l ight sandy, or organic ;oils, t h a n i n heavy compact soils (e.g: Busgen and Munch, 1929).

9.5 Root regeneration

When conifer seedlings are transplanted or l i f t e d many of the roots are broken and l e f t behind. The a b i l i t y of seedlings t o regenerate new roots when replanted may have an e f fec t on t he i r ab i l i t y t o survive. Stone e t aZ. (1962) investigated roo t regeneration of three-year-old Douglas f i r plants from Washington and concluded t h a t root regeneration potential was low during the summer months, rose sharply in September, remained high during winter, and dropped a g a i n i n April. An inverse relationship between r o o t regeneration potential and mortality was thought to exist. On the other hand, low r o o t regeneration ability was found in Douglas f i r during November and December although field survival was high (Winjum, 1963).

Root regeneration potential cannot completely explain survival if i t rea l ly i s low throughout the summer because Douglas f i r can be successfully transplanted i n early July. Apparently the second period of r o o t ac t iv i ty which occurs a t th i s time of year allows plants t o become established. Advantage of t h i s second period of r o o t ac t iv i ty i s a l so taken in Ontario for summer transplanting of spruce and pine t o obtain three-year-old l%-1% transplants.

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LIBRARY MINISTRY OF FORESTS PARIAMENT BUILDINGS

V8W 3E7 VICTORIA, B.C. 25.

10. Transplanting and r o o t pruning

10.1 General

The purpose of transplanting is t o ensure t h a t the seedling has an adequate, b u t easily handled, roo t system. Long roots are broken off by transplanting and secondary roots close t o the base of the stem are en- couraged t o develop. Transplants have a larger number of shorter roots t h a n seedl i ngs of the same age (9 .4 ) . Transplanting involves much hand labour and is therefore expensive, so the entirely mechanized procedure of root pruning i s used t o achieve the same ends. Roots of drill-sown seedlings can be pruned by undercutting with a horizontal blade, or la teral pruned by drawing vertical blades between the dri 11s.

10 .2 Transplanting

Transplanting i s usually carried o u t as early as possible in spring (March or April ). I t can be done in fall before November i n coastal nurseries, when some roo t growth can be expected before winter in transplant beds. This is desirable t o avoid frost-heaving. Fall transplanting gives unsatisfactory survival compared with spring transplanting.

I t i s possible t o transplant i n July to take advantage of the summer period of root activity (9.3). The pract ice is common i n Ontario, where l&-l& white spruce transplants are widely used. I t has been successfully carried o u t a t Red Rock nursery with Douglas f i r , white spruce, and lodgepole pine. I t i s advisable t o thoroughly irrigate the stock before lifting and also irr igate the transplant beds carefully.

10.3 Root pruning

Undercutting i s normally carried o u t a t the beginning of April on seedl i n g s commencing their second growing season. This undercutting a t a depth of 6-9 inches occurs when early spring root activity is nearly complete (9 .3) . I t i s quest ionable how many roots are really cut by th i s procedure, and t o what extent roo t growth is stimulated by soil disturbance causing improved aeration, etc. Seed lo t s which are to be l i f t ed for fall planting are frequently undercut in late July in coastal nurseries. This causes cessation of height growth and terminal bud formation, probably because water uptake i s decreased due t o loss of roots.

Undercutting broadcast sown 3-0 white spruce a t two depths ( 2 and 4 inches) was t r ied a t various times of year (Mullin, 1966). There was no nursery mortality from undercutting in September (as 2-0) in Apri 1 , i n May, or i n late June, Root p r u n i n g i n l a t e June (25 June) d i d s l igh t ly increase height growth (1 cm a f t e r 5 years) and survival (by 8%) in the f i e ld compared with control. The other treatments showed no benefit.

Lateral r o o t pruning with sharp knives effectively cuts roots, b u t causes l i t t le soi l d is turbance. I t is usually carried o u t in late June, and may be done again later in the season.

26.

W Most Douglas fir provenances can be expected t o make f u r t h e r r o o t

g r o w t h a f t e r p r u n i n g a t any da te un t i l Ju l y . P run ing du r ing l a te Ju l y and August cannot be expected to immediately cause a denser roo t sys tem, bu t will not iceab ly reduce shoot g rowth , and may even cause death o f l o w e r needles i f i r r i g a t i o n i s n o t adequate.

The o b j e c t i v e s o f r o o t p r u n i n g s h o u l d b e h e l d c l e a r l y i n mind, t h a t i s , w h e t h e r t h e i n t e n t i o n i s t o i n c r e a s e t h e p r o p o r t i o n o f s h o r t r o o t s , o r t o h o l d b a c k g r o w t h . S u i t a b l e t i m i n g a n d f r e q u e n c y o f r o o t p r u n i n g c a n t h e n b e d e t e r m i n e d , t a k i n g t h e i n f o r m a t i o n i n s e c t i o n 9 i n t o a c c o u n t .

11

11.1 Dormancy

Dormant con growi ng po ints .

1. Summer

. Dormancy, f r o s t h a r d i n e s s , and l i f t i n g

i f e r s e e d l i n g s make no extension growth and have buds a t t h e It i s common t o d i s t i n g u i s h two types o f dormancy:

dormancy, induced by adverse environmental condi t ions , and reversed by favourab le cond i t ions .

2. Win ter dormancy , ma in ta ined by in te rna l fac to rs , wh ich can on ly be b roken adequa te l y a f te r a c h i l l i n g r e q u i r e m e n t has been s a t i s f i e d .

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D u r i n g t h e f i r s t y e a r o f g r o w t h D o u g l a s fir seed l i ngs o f mos t coas ta l provenances will grow cont inuously i f w e l l s u p p l i e d w i t h w a t e r and n u t r i e n t s . They e n t e r w i n t e r dormancy i n the autumn i n response t o decrease i n day leng th . They will f l u s h a g a i n i f first s u b j e c t e d t o 8 weeks a t 40° F, o r an e q u i v a l e n t c h i l l i n g p e r i o d , and then prov ided wi th h igher temperatures and longer days. Winter dormant Douglas fir seem t o f l u s h s l o w l y and i r r e g u l a r l y , o f t e n s t a r t i n g w i t h l o w e r l a t e r a l s , i f p rov ided w i th f avou rab le g row ing cond i t i ons , b u t no c h i l l i n g p e r i o d . A f t e r t h e f i r s t y e a r Douglas fir grows by f lushes. A number o f l e a f p r i m o r d i a a r e f o r m e d w i t h i n a bud, and a f te r t hese have expanded a new bud i s f o rmed be fo re t he nex t pe r iod o f ex tens ion g rowth can occur. When c o n d i t i o n s a r e f a v o u r a b l e s e v e r a l f l u s h e s ( p e r i o d s o f e x t e n s i o n growth) may occur dur ing the second year of growth. Under unfavourable cond i t i ons pe rhaps on l y one f l u s h may occur , and seedl ings enter summer dormancy, which u l t i m a t e l y passes t o w i n t e r dormancy as the season progresses. I n t h i s c o n n e c t i o n i t s h o u l d b e n o t e d t h a t n o t a l l c o n i f e r s grow by f lushes a f t e r t h e f i r s t y e a r o f i n d e t e r m i n a t e g r o w t h . F o r example, a t l e a s t some, and perhaps a l l , provenances o f S i t k a s p r u c e show cont inuous ex tens ion g rowth d u r i n g t h e first few years o f g rowth under favourab le cond i t ions .

11.2 F ros t ha rd iness

I n t h e n u r s e r y s e e d l i n g s w i t h w e l l f o r m e d buds are seldom damaged by e a r l y f a l l o r l a t e s p r i n g f r o s t s . T h i s i s because such f r o s t s a r e u s u a l l y o n l y a few degrees below f reezing point . Dormant seedl ings, as descr ibed above (1 1.1 ) , a r e n o t , however , necessa r i l y ve ry f ros t ha rdy . Two-year -o ld Douglas fir seed l ings f requent ly cease ex tens ion g rowth and form buds i n c o a s t a l n u r s e r i e s i n September, b u t do no t deve lop much f r o s t h a r d i n e s s u n t i l t h e e n d o f O c t o b e r . S i m i l a r l y t h e y s t a r t 1 o s i ng f r o s t h a r d i n e s s r a p i d l y

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a t t h e b e g i n n i n g o f March a l though f lush ing does no t occu r be fo re m id -Apr i l (van den Dr iessche, 1969b). Non-hardy seedl ings can be protected f rom f rost t o some ex ten t by sp r ink l i ng ( see 8 .5 ) .

The c o n d i t i o n s u s e d f o r c o l d s t o r a g e o f s e e d l i n g s a f t e r l i f t i n g ( a b o u t 35' F i n darkness) apparent ly do not cause increase or decrease i n hard iness. Thus, seedl i ngs 1 i f t e d and s t o r e d i n e a r l y O c t o b e r wi 11 remain non-hardy , and i f p l a n t e d o u t l a t e r i n t h e f a l l , o r e a r l y i n s p r i n g , a r e l i k e l y t o r e c e i v e f r o s t damage. On t h e o t h e r hand, s e e d l i n g s l i f t e d and s t o r e d i n J a n u a r y will r e m a i n f r o s t h a r d y i n s t o r a g e f o r s e v e r a l m o n t h s .

Douglas fir s e e d l i n g s r e q u i r e l i g h t t o h a r d e n . They will harden s a t i s f a c t o r i l y i n c o l d s t o r a g e i f p r o v i d e d w i t h l o w i n t e n s i t y l i g h t . They will presumably harden a f ter 1 i f t i n g i n t h e autumn i f l e f t exposed i n t h e open, b u t t h i s p e r m i t s d e s s i c a t i o n . To o b t a i n f r o s t h a r d y v i a b l e s e e d l i n g s , t h e r e - f o r e , l i f t i n g must be con f ined to the per iod mid-October to ear ly March i n coas ta l nu rse r ies .

11.3 L i f t i n g

The main problem i n l i f t i n g n u r s e r y s t o c k i s t o a v o i d damage t o s e e d l i n g s . Var ious types o f mechanical damage a re reduced by ca re and a t ten t i on t o t he l i f t i n g o p e r a t i o n , p a r t i c u l a r l y a d e q u a t e l o o s e n i n g o f t h e p l a n t s i n t h e s o i l p r i o r t o l i f t i n g o u t . D e s s i c a t i o n i s always a p o t e n t i a l h a z a r d and i s l a r g e l y avoided by a lways keeping roots covered (heel ing- in i f necessary) and keeping p l a n t s o u t o f w i n d a n d d i r e c t s u n s h i n e . The f a s t e r t h e l i f t e d p l a n t s can be p laced i n t h e p l a s t i c 1 i n e d s h i p p i n g bags t h e s h o r t e r will be t h e o p p o r t u n i t y f o r d r y i n g . P l a n t s m u s t be p laced so t h a t s h o o t s a r e up and r o o t s down if l o n g p e r i o d s i n s t o r a g e a r e a n t i c i p a t e d . C o n d e n s a t i o n t h e n r u n s t o r o o t s and does no t cause mou ld ing o f f o l i age .

12 . So i l and p l a n t t i s s u e a n a l y s i s

12.1 S o i l a n a l y s i s

The purpose o f s o i l a n a l y s i s i s t o d e t e r m i n e w h e t h e r t h e r e i s a s u f f i c i e n t q u a n t i t y o f each n u t r i e n t a v a i l a b l e t o p e r m i t s a t i s f a c t o r y g r o w t h o f the c rop . There may b e v e r y l a r g e q u a n t i t i e s o f a nu t r i en t , such as potassium ( K ) , i n t h e s o i l , b u t o n l y a s m a l l f r a c t i o n o f t h i s will be a v a i l a b l e t o t h e c r o p . K o c c u r s w i d e l y i n t h e s o i l as potassium alumino s i l i c a t e (e .g . f e ldspar ) , bu t t he K i n t h i s compound o n l y becomes a v a i l a b l e t o p l a n t s when p o t a s s i u m a l u m i n o s i l i c a t e i s decomposed by weather ing. The same s i t u a t i o n e x i s t s w i t h r e g a r d t o o t h e r n u t r i e n t s , e x c e p t t h a t s o i l n i t rogen (N) and phosphorus ( P ) r e s e r v e s a r e u s u a l l y o r g a n i c compounds and re la t i ve l y sca rce . Consequen t l y measurement o f t o t a l n u t r i e n t c o n t e n t o f t h e s o i l p r o v i d e s no i n fo rma t ion abou t t he amount o f n u t r i e n t a v a i l a b l e t o the p lan t . Ins tead severa l methods o f e x t r a c t i o n have been devised which a r e t h o u g h t t o remove about as much n u t r i e n t f r o m t h e s o i l as t h e r o o t s o f t h e c r o p p l a n t c o u l d remove.

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The usefulness of any extraction method chosen depends on how we1 1 the quantities of nutrient extracted permit prediction of crop growth. In other words, the relationship between extraction method and crop growth is largely empirical. I n the case of P, fo r example, i t i s necessary t o choose a method sui table t o b o t h soi 1 and crop. Measurement of available cations ( K , calcium ( C a ) , magnesium (Mg)) i s usually simpler and more sat isfactory, apparently because their avai labi 1 i ty depends largely on a base exchange process. There i s no simple chemical tes t for avai lable soi l N . Total Kjeldahl N analysis merely shows t h a t i f t he re i s no N of any sort present there is certainly no available N . On the other hand, h i g h total N analysis values do n o t imply presence of available N . A t the old Quinsam nursery soi l to ta l N values in excess of 0.3% were frequently obtained, b u t crop response t o N f e r t i l i z e r was grea te r a t Quinsam t h a n a t Duncan or Green Timbers where total N values were normally less than 0.2%.

When an extraction method has been chosen i t i s necessary t o cal ibrate i t i n terms of crop response. For example, does 100 ppm P , extracted with 0.05 normal HF, show t h a t there i s enough P t o grow Douglas f i r ? What does th i s same 100 ppm P mean fo r growth of hemlock, Sitka spruce or Inter ior spruce? Would 100 ppm P in s i l t loam a t Duncan mean the same as 100 ppm P in sand a t Red Rock? Calibration has t o be achieved by means of f ie ld plots treated w i t h different quantit ies of the nutrient i n question. For greatest accuracy such plots should be laid o u t on each type of so i l fo r each species. Such work i s , however, time-consuming and laborious, and a b o u t a l l t h a t has been done in this direction is obtain information relating nutrient levels i n coastal s i l t loams t o growth of Douglas f i r seedlings. These relation- ships are errat ic even within the same nursery, possibly because of i r r iga t ion i r regular i t ies or soil microflora differences, and provide a rather vague basis for f e r t i l i z e r recommendations.

Despite the limitations of soil analysis, careful maintenance of so i l management records, together with analysis, allows the nurseryman t o build a clearer picture of the s ta te of h i s so i l , and judge more accurately whether i t s f e r t i l i t y i s increasing or decreasing.

12 .2 Type of analysis for established and prospective nurseries

Measurement of soil pH ( 3 . 0 ) , available nutrients, and organic matter content are valuable i n established nurseries (see 13.1 a-g before taking samples). There i s l i t t l e p o i n t in measuring cation exchange capacity ( C . E . C . indicates abi l i ty of soil t o retain cations such as K , Ca and Mg) a t more than 3-5 year intervals, unless peat has been added t o the so i l . Total (Kjeldahl) N% i s usually closely correlated with organic matter %. Total N% does n o t provide a re l iab le guide t o available N b u t does indicate the level of organic matter.

The most useful analyses t o obtain from prospective nursery sites are pH, organic matter content, sand , s i l t , and clay fractions, and C . E . C . There i s no value in determining mineral nutrient content since this is n o t considered in deciding the su i t ab i l i t y of a s i t e f o r a nursery. This i s reasonable since low mineral nutrient levels can be rect i f ied easi ly and cheaply with a r t i f i c i a l f e r t i l i z e r s .

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Conductivity of samples from potential nursery sites i n the Interior should be measured to ensure t h a t soluble salts are not present i n h i g h concentration.

12.3 Levels of soi l nutr ients

On the basis of a large number of soil analyses carried out by Research Division laboratory, and spec i f ic experiments (e.g. van den Driessche, 1963~1, 1969a),desirable nutrient levels for a Douglas f i r nursery have been general l y determined (Tab1 e 10).

Table 10. Level of nursery so i l nutrients considered adequate f o r growth of Douglas f i r .

pH % organic % N p PPm K Ca Mg C . E . C . matter (Kjeldahl) (Bray 1 ) (m.e.q./100 g dry s o i l )

4.8 5-8 0.20 100 .20 5.0 <1.4 15

-5.2 -0.25 -1 50 -.30 -8.0 (0.8?) - 20

The way changes i n s o i l f e r t i l i t y can be traced by analysis i s exemplified by resu l t s from Duncan and Green Timbers, which are b o t h s i tuated on s i l t loams (Table 11). Green Timbers received heavy applications of Ca and Mg f e r t i l i z e r s between 1946 and 1961. Dur ing this time large dressings of farmyard manure (previously used f o r growing mushrooms) , which contained K f e r t i l i z e r , maintained the organic matter level, b u t raised K t o an undesirably h i g h level . F e r t i l i t y amendments a t Duncan were better suited to the requirements of a conifer nursery d u r i n g the same period, though both organic matter and so i l K decreased t o an undesirably low level. Since 1961 an attempt has been made to increase organic matter level and nut r ien ts a t Duncan, and allow available cations, particularly K, to decrease a t Green Timbers.

Table 11. Average soil analyses for two coastal nurseries.

Analysi s Nursery Duncan (Field 1 ) Green Timbers(Fie1ds 1 & 2 )

Year of analysis 1947 1961 1969 1946 1961 1969

PH 5.70 5.65 4.99 5.50 6.49 6.11 Organic matter % 5.61 3.62 5.51 8.25 8.20 6.74 % N (Kjeldahl) - 0.17 0.18 - 0.28 0.18 p ppm (Bray 2 ) 119 89 179 205 197 21 3 K m.e.q./lOOg 0.27 0.14 0.18 0.16 0.62 0.20

8.33 6.10 4.78 2.31 11.14 4.41 0.94 1.10 1.01 0.10 3.86 0.38

17.10 17.20 20.55 14.90 27.90 24.76

Ca

Mg C . E . C .

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E f f e c t i v e n e s s o f an a p p l i c a t i o n o f 100 cu . yd /ac re o f l oca l pea t , o f known composi t ion, i n i n c r e a s i n g o r g a n i c m a t t e r c o n t e n t , C.E.C., and t o t a l N% a t K o k s i l a h n u r s e r y ( a s i l t l o a m t o sandy loam) was measured by s o i l a n a l y s i s (Tab le 12) . Th is t ype o f ana lys is i s va luab le because i t a l l ows t he nu rse ry - man t o p r e d i c t how much p e a t will b e r e q u i r e d t o r a i s e s o i l o r g a n i c m a t t e r a p a r t i c u l a r amount. I n t h i s case about 53 c u y d / a c r e o f p e a t , c o n t a i n i n g 66% o r g a n i c m a t t e r , r a i s e d t h e l e v e l o f s o i l o r g a n i c m a t t e r b y 1%.

T a b l e 1 2 . A n a l y s i s o f l o c a l p e a t , and change i n s o i l a n a l y s i s v a l u e s 10 months a f t e r t r e a t m e n t w i t h t h i s p e a t a t 100 cu yd per acre.

Ana lys i s Loca l peat Unt rea ted so i 1 Soi 1 t r e a t e d w i t h Aug., 1966 1 oca1 p e a t -

Aug., 1966

PH 4.50 5.51 5.22

Organ ic mat te r % 65.8 3.6 5.5

% N ( K j e l d a h l )

p PPm (Bray 1 )

1.52

71

K m.e.q./lOOg 0.70

Ca I1 31.00

0.17

52

0.14

8.04

0.21

52

0.15

8.93

Mg I I 10.70 0.95 1.46

C.E.C. I I 155.70 14.80 17.70

12 .4 Seed l i ng t i ssue ana lys i s

Rather than guessing how much o f a n u t r i e n t i n t h e s o i l o u g h t t o be a v a i l a b l e t o a p l a n t , t i s s u e a n a l y s i s a l l o w s measurement o f how much n u t r i e n t t h e p l a n t a c t u a l l y a b s o r b s . T h i s i s a more d i r e c t approach and has the advan tage t ha t , once t he t i ssue nu t r i en t re la t i onsh ips o f a species i s known, i t shou ld be app l i cab le on any so i l . The p r o b l e m l i e s i n d e c i d i n g w h a t t h e t i s s u e n u t r i e n t r e l a t i o n s h i p s a r e . F o r example, a n a l y s i s o f a s e e d l i n g m i g h t r e v e a l a h i g h t i s s u e P %. This cou ld be due t o l o w s o i l l e v e l o f some o t h e r e l e m e n t l i m i t i n g g r o w t h so t h a t P a c c u m u l a t e s , o r s i m p l y t o h i g h s o i l l e v e l o f P. Even when d e a l i n g w i t h o n l y f i v e n u t r i e n t s , N, P, K, Ca and Mg, t h e r e l a t i o n s h i p s c a n become d i f f i c u l t t o i n t e r p r e t , p a r t i c u l a r l y s i n c e u p t a k e of one n u t r i e n t may a f f e c t u p t a k e o f a n o t h e r . When an u n u s u a l l y l o w t i s s u e n u t r i e n t c o n c e n t r a t i o n i s d e t e c t e d b y a n a l y s i s , however, i t i s u s u a l l y f a i r l y s a f e t o assume t h a t i n c r e a s e d s u p p l y o f t h i s n u t r i e n t will improve growth. Hence t i s s u e n u t r i e n t c o n c e n t r a t i o n s b e l o w w h i c h g r o w t h i s l i k e l y t o be s e v e r e l y r e s t r i c t e d can be determined. These minimum c o n c e n t r a t i o n s , o r

" c r i t i c a l c o n c e n t r a t i o n s " , can n o t be p r e c i s e because the quan t i t y o f eve ry o t h e r n u t r i e n t p r e s e n t will have some e f f e c t on t h e amount o f g r o w t h .

31.

W Tissue analysis i s probably no more precise than soil analysis for

suggesting how fer t i l izer t reatments should be modified and supplemented. I t requires the same so r t of field plot calibration as soil analysis, and sampling i s res t r ic ted with regard t o time of year and age of crop. Lab- oratory analysis is fas ter , however, and interpretation of r e su l t s i s probably appl icabl e to a range of nursery conditions.

12.5 Type of t issue analyzed

Conifer tissue nutrient concentration varies with season and i t i s con- ventional to sample seedlings in late au tumn or early winter when nutrient levels are relatively stable. In sampling nursery-grown conifers entire shoots, or whole plants, have commonly been analyzed. From such d a t a estimates of total nutrient uptake by the crop are readily obtained. Analysis of foliage alone, or even a few apical whorls o f needles, may, however, be more useful for determining whether the crop i s adequately supplied with nutrients.

12.6 Levels o f tissue macronutrients

On the basis of several experiments and a review of l i terature the N, P and K levels t o be expected i n 1-0 Douglas f i r and Sitka spruce whole seed- l ings, or foliage have been tabulated (Table 13) (van den Driessche, 1 9 6 9 ~ ) .

Table 13. October levels of t issue N , P and K per cent for Douglas f i r and Sitka spruce.

Levels* N P K

Douglas Sitka Doug1 as Sitka Douglas Sitka f i r spruce f i r spruce f i r spruce

Concentration (%) in 1 year needles

Adequate k2.0 k2.3 20.40 k0.33 +1.2 k1 .2

Low 1 .5 1 . 9 0.25 0.24 0.6 0 .6

Very low 1 .o 1 . 2 0.17 0.16 0.4 0.4

Concentration (%) in 1 year seedlings

Adequate k1.7 k2.1 k0.30 k0. 25 k 1 . 2 k1.2

Low 1 .4 1 . 7 0.23 0 .22 0.6 0.6

Very low 0.8 1 .o 0.17 0.16 0.4 0.4

w * "Low1' - possibly limiting growth, "very low" - probably 1 imi t i n g growth.

32.

PJ

Adequate t issue Ca l e v e l f o r whole 1-0 Douglas fir and S i t ka sp ruce s e e d l i n g s i s a b o u t 0.20%. Adequate t i s s u e Mg l e v e l s f o r t h e two species a r e r e s p e c t i v e l y a b o u t 0.12% and 0.15%. Douglas fir s e e d l i n g s o f I n t e r i o r provenance tend to show h i g h e r t i s s u e N % values than coastal provenances.

T i s s u e n u t r i e n t c o n c e n t r a t i o n s i n hemlock have n o t been e x t e n s i v e l y s tud ied . Va lues fo r shoots o f seed l ings g rown i n sand c u l t u r e f o r 1 4 weeks w i t h an adequate supply o f n u t r i e n t s were: N 1.98%, P 0.50%, K 1.71%, and Mg 0.28% (Swan, 1960).

M ine ra l nu t r i en t concen t ra t i ons o f who le 1%-year -o ld t ransp lan ts meas- u red i n J u l y a r e p r e s e n t e d f o r f o u r s p e c i e s ( T a b l e 1 4 ) . These analyses were o b t a i n e d f r o m s e e d l i n g s p l a n t e d i n a randomized block experiment a t two coas ta l nurser ies and a re , there fore , use fu l fo r compara t ive purposes . These data, and other analyses which al low comparison (e.g. Smith e t aZ. 1968) , suggest tha t t i ssue N c o n c e n t r a t i o n o f h e m l o c k i s l o w e r t h a n t h a t o f e i t h e r Dougl as fir o r S i t ka sp ruce .

T a b l e 1 4 . N u t r i e n t c o n c e n t r a t i o n o f 1 % - y e a r - o l d t r a n s p l a n t s i n J u l y .

Treatment and spec ies Nu t r i en t concen t ra t i on % o f d r y w e i g h t

U n f e r t i 1 i zed N P K Ca M g

Douglas fir 1 .26* .18 .60 .27 .14

Hemlock 1.03 .16 .69 .28 .14

S i t ka sp ruce 1.21 .17 .62 .30 .18

White spruce 1.63 .20 .76 .33 .20

F e r t i 1 i zed**

Dougl as fir 1.41 .19 .61 .36 .24

Hem1 ock 1.31 .18 .84 .39 .24

S i t ka sp ruce 1.42 .24 .67 .39 .22

White spruce 1.72 .19 .73 .39 .18

* Averages based on 40 p lan ts f rom each o f 8 p l o t s . ** N, P and K w e r e e a c h a p p l i e d a t 8 0 l b s / a c t o f e r t i l i z e d p l o t s .

Concent ra t ion o f N i n I n t e r i o r s p r u c e t e n d s t o b e h i g h e r t h a n i n coastal species. There i s e s s e n t i a l l y no d i f f e rence be tween range o f N, P and K c o n c e n t r a t i o n s i n b l a c k s p r u c e (Picea marianu ( M i l l . ) BSP. ) and i n wh i te spruce (P. gZauca (Moench) Voss) (Armson and Carman, 1961). The

33.

W ranges encountered i n O n t a r i o a r e shown by ages (Table 15). The N, Ca and Mg p e r c e n t o f 2-0 whole white spruce was lower than i n s i m i l a r 1 - 0 w h i t e spruce a t Red Rock nu rse ry , bu t t he concen t ra t i on o f P and K d id no t dec rease (Table 16) . Increase i n N f e r t i l i z a t i o n common1.y decreases P p e r c e n t o f 1-0 whi te -spruce, though caus ing an i n c r e a s e o f g r o w t h and N c o n c e n t r a t i o n (Tab le 17) .

Tab le 15 . Nut r ien t concent ra t ion ranges i n c u r r e n t f o l i a g e o f W h i t e s p r u c e i n O n t a r i o . ( A f t e r Armson and Carman 1961)

Seed1 i ng age N u t r i e n t c o n c e n t r a t i o n % o f d r y w e i g h t

1-0

2- 0

2+ 1

2.00-2.40 0.25-0.35 0.60-1 .OO

2.00-2.40 0.20-0.30 0.50-0.80

1.90-2.40 0.18-0.24 0.45-0.60

Tab le 16 . Average nu t r ien t concent ra t ions o f 1 -0 and 2-0 White spruce seedlings grown i n an NPK f a c t o r i a l e x p e r i m e n t a t Red Rock nursery.

Age Concent ra t ion (%) o f n u t r i e n t i n w h o l e s e e d l i n g

N P K Ca M g

1-0 2.23 0.25 0.88 0.27 0.19

2-0 1.69 0.29 0.87 0.24 0.13

T a b l e 1 7 . E f f e c t o f r4 t rea tment on whole 1-0 seedl ing dry weight and n u t r i e n t c o n c e n t r a t i o n a t Red Rock nursery.

N t rea tment Dry we igh t N u t r i e n t c o n c e n t r a t i o n % ( l b s / a c r e ) ( 9 ) N P K Ca rJl g

0 0.031 2.17 0.27 0.83 0.26 0.20

40 0.034 2.13 0.25 0.92 0.29 0.19

80 0.036 2.38 0.23 0.90 0.26 0.18

34.

12.7 Levels o f t i s s u e m i c r o n u t r i e n t s W

4

W

It i s p o s s i b l e f o r g r o w t h o f s e e d l i n g s i n n u r s e r i e s t o b e l i m i t e d b y m ic ronu t r i en t de f i c ienc ies (e .g . Benz ian 1965, p. 94, K o r s t i a n e t aZ.1921), b u t t e s t s w i t h b o r o n ( B ) and z inc (Zn ) , and an exper iment inc lud ing manganese (Mn) , molybdenum (Mo) copper (Cu) , and i r o n ( F e ) showed no conc lus ive improve- ment i n Douglas fir growth (van den Driessche 1963a, 1968, 196%). Levels of m i c r o n u t r i e n t s i n f o l i a g e o f c o n i f e r s w h i c h may be grown i n B.C. n u r s e r i e s have been abstracted (Table 18) f rom a r e v i e w o f m i c r o e l e m e n t n u t r i t i o n o f f o r e s t t r e e s ( S t o n e 1 9 6 8 ) .

Measurement o f m i c r o n u t r i e n t l e v e l s i n w h o l e D o u g l a s fir s e e d l i n g s , a f t e r thorough root washing, ranged f rom 30-101 ppm f o r B, 108-180 ppm f o r Mn, and 47-66 ppm f o r Zn. The h ighe r va lues were assoc ia ted w i th app l i ca t i ons o f t r a c e e lemen t che la tes t o t he seed l i ngs . The exper iment f rom which these data were drawn a l s o showed t h a t P f e r t i l i z e r and s o i l s t e r i l a n t s m a r k e d l y a f f e c t e d p l a n t u p t a k e o f Zn and Mn.

I n g e n e r a l , i n f o r m a t i o n a b o u t m i c r o n u t r i e n t r e q u i r e m e n t s o f w e s t e r n c o n i f e r s i s s c a n t y .

Table 18. Concentrat ion o f m i c r o n u t r i e n t s i n f o l i a g e o f some western c o n i f e r s .

Micro- Doug1 as S i t k a Whi t e Lodgepol e n u t r i e n t L e v e l fir spruce Hem1 ock spruce p i ne

ppm dry m a t t e r

B Norma 1 9-39 17-28 17 16-30

Low 5 5 4.3

cu Norma 1 5.1-7.7 7.0-10.8 3.9-4.1 4.0-4.7

Low 2.7

D e f i c i e n t 2.4-5.1 2.3-2.8

M n Normal 390-1 294 1598-2043 1583-1876 672-1 052 293

Zn Normal 17-63 42-57 10 59-1 17 52

Low 3

Fe Low 39-51 39-59 58

35.

13. Soil and seedling sampling

13.1 Soil sampling

yrl

13.1 ( a ) Intensity of sampling.

In established nurseries the sampling units should be the management unit. There i s no purpose in obtaining a number of individual analyses from a single nursery field on which i t i s intended t o ra ise a single crop under one f e r t i l i z e r , i r r iga t ion , and cultivation regime. Samples should be removed from each management unit a t the rate of abou t 6 per acre and bulked before being sent t o the laboratory.

Potential nursery sites in this Province are rarely uniform. The surveyor must s t ra t i fy the area, as far as possible, into such categories as bottomland, slope, terrace, e tc . These areas should then be sampled separately a t a ra te of about 6 samples per acre. The samples should be bulked and a small number from each category forwarded t o the laboratory for analysis. The number of bulk samples obviously depends upon the area in each category, b u t n o t more than 18 samples (3 acres) should be bulked.

13.1 ( b ) Determining sample point.

The most sat isfactory method consists of laying o u t a square grid and removing samples where the grid lines intersect . In t h i s way the area i s sampled systematically. A grid forming rectangles with sides 75' x 100' long will provide 6 samples per acre.

13.1 ( c ) Depth of sampling.

In established nurseries samples s h o u l d be removed from the 0-6 inch layer (plough-layer).

Examination of the physical characteristics of the soil t o a depth of a t l eas t 3 feet i s desirable for potent ia l nursery s i t e s . This can be done adequately by visual examin- a t ion. Samples for laboratory analysis should be mainly confined t o the 0-6 inch 1 ayer, a1 t h o u g h i t may be prudent t o check analytical values on a few samples from greater depth.

-

13.1 ( d ) Accuracy of sampling.

Soil must be taken in equal quantity from the who1 e horizon or depth layer which i t i s intended t o represent. The 6-inch layer of a nursery can most readily be sampled using a soil sampling tube.

w 13.1 ( e ) Bulking.

When composite "bulk" samples are prepared i t i s essential t h a t individual samples are thoroughly mixed.

36.

This i s conveniently achieved by emptying a l l samples ( n o t more than 18) t o be bulked i n t o a stout polyethylene bag and mixing them with a trowel. After thorough mixing about a p i n t of so i l i s removed and placed in a labelled container for transmission t o the 1 aboratory.

13.1 ( f ) Sample s ize .

A mineral soi l sample of 1 pint in volume ( a b o u t 1.5 lbs. ) i s adequate f o r a l l analyses normally carried o u t . Organic soils or peat samples should be twice this s ize i f sampled wet. A peat sample may shrink t o & the original volume on drying. Soil samples should be placed in 1 pint cardboard cartons. Failing cardboard cartons, stout kraft paper bags (obtainable a t groceries) are acceptable. Samples should n o t be placed in a i r - t ight plast ic bags (e.g. plastic lined seedling bags) or plastic cartons.

-

13.1 ( 9 ) Labelling.

Each sample must be clearly identified with the following i nf orma t i on :

1 . Sample number. This may re la te t o an area, or i n some cases, a p o i n t on an accompanying diagram.

2. Date sample taken.

3. Place, e.g. Chilliwack.

4. Location, e.g. Borden Creek Nursery, Field 1 .

5. Horizon, e. g . 0-6 inch layer.

6. How many individual samples were mixed t o form the present bulk sample.

Only the sample number need be p u t on the sample container and the remaining information can be shown against the corresponding number on an accompanying sheet of paper. This sheet of information should be f i l l ed ou t a t the time the samples a re taken and accompany the samples t o the 1 aboratory. (Read 12 .2 before requesting analyses. )

13.2 Seedling sampling

13.2 ( a ) Size of sample.

Seedling samples are removed from nursery fields containing 1-0 stock each a u t u m n , for chemical analysis . Fer t i l izer applications can be supplemented during the second year of growth if nutrient deficiencies are detected by this analysis. A t present 20 entire seedlings are considered t o consti tute a sample. A nursery fie1 d of u p t o 4 acres i s sampled by

37.

W choosing two beds in each of the two seed lo t s , and removing 20 seed1 ings from each. Two more beds in another seed l o t should be sampled for each additional 4 acres in the field.

13.2 ( b ) Method of sampling.

The 20 seedling sample should be dug from near the middle of the bed. Care should be taken t o obtain complete root systems, and sampling of patches of abnormally large, or small, seedlings i s t o be avoided in a u t u m n sampling. A u t u m n sampling should be carried o u t on 15 October, or as close t o this date as possible.

13.2 (c) Labelling.

Each sample of 20 seedlings must bear a label providing de ta i l s , i n waterproof writing, of species, sample number, seed l o t number, sowing date, date sample l i f t e d , f i e l d number, and nursery.

13.2 ( d ) Despatching.

Seedling samples for analysis should be despatched by the fas tes t means t o the laboratory in plastic lined seedling bags.

14. Choice of nursery s i t e s

14.1 General

A large number of factors are 1 i kely t o influence the choice of nursery s i t e s . Considerations of e l ec t r i c power supply , avai labi 1 i ty of labour , and cost of land frequently have a major influence, b u t no nursery will be satisfactory unless the conditions outlined below are a lso sat isf ied. These conditions have been f o u n d universally desirable for economical operation o f conifer nurseries, j u d g i n g b o t h from the l i t e r a tu re , and from nursery pract ice in , for example, Ontario or Germany. I n British Columbia these conditions are perhaps hard t o s a t i s fy , because of topography and nature of the s o i l , so t h a t some of the f i r s t nurser ies were developed on heavy agri- cultural soi 1s ( s i 1 t loams). Drainage and weed problems , and poor working qual i t ies of the soi 1 have emphasized t h a t these s i tes were n o t sui table.

14.2 Soil texture

U

Nurseries must be on loamy sands with good drainage (Mi kol a 1959 , p. 77, Forestry Commission 1964, p. 1 . ) . Light soils can be worked when weather conditions are too wet for working heavier soils, and they normally do not present the same chronic weed problems of heavier soi 1s. The content of clay and s i l t (par t ic les smaller t h a n 0.05 mm diam.) in a nursery soil should not exceed 20%, and certainly n o t be more than 25%.

38.

14.3 Soil pH and organic matter content

For satisfactory growth of conifers soil should be more acid t h a n pH 6 , and may be as acid as pH 4.5. Organic matter content should l i e in the range 5-8%.

14.4 Soil depth

A soil depth of 4 f ee t , f r ee of claypan, hardpan, shale, iron concretions, calcareous substrata, or mottled gley layers, i s des i rab le for a nursery s i t e

minimum. With art if icial drainage, however, a minimum clear soi l depth of 2 f e e t i s probably acceptable. This allows roughly one foot for r o o t develop-

,I (Wilde 1958, p. 323). Without art if icial drainage this seems a reasonable

c ment of 2-0 stock and one foot through which water can move t o t i l e d ra ins .

14.5 Water table

Nurseries must be on land with good drainage where the water table remains several feet below the soil surface throughout the year. Nursery s i t e s are seldom selected in winter when s o i l s , which appear dry in summer, may show unexpectedly high water tables. High water tables for even short periods may make a site unsuitable as a nursery.

14.6 Water supply

V

Lack of adequate water supply with sui table pH (pH 7 or lower) may render an otherwise suitable site useless. I t i s important t o ascertain t h a t the water supply does n o t contain Cay or dissolved alkaline salts, besides determining t h a t quantity and accessibi l i ty are sat isfactory. Maximum water consumption by a nursery for all purposes migh t amount to 5 inches per month . This necessitates a supply of 136,000 gals per acre per month , or about 4,500 gals per acre per day.

14.7 Topography

A nursery s i t e should e i ther be level, or have a slope n o t exceeding 6' (c . f . Wakeley 1954, p. 70) . Now t h a t machinery i s extensively used in the nursery a uniform slope w i t h rectangular, o r other regular, boundaries i s des i rabl e.

14.8 Climate

Nursery s i t e s should be located in climatically suitable areas. In particular, frost pockets must be avoided, and the s i t e should n o t be subject t o heavy snow f a l l s which delay the s t a r t o f spring work.

14.9 Examination o f potential si tes

There are a large number of points t o be examined a t any potential nursery s i t e . I t i s very easy t o overlook some of them when examining s i t e s

in the field. I t i s s t rongly recommended, therefore, t h a t sheets of paper are drawn up with appropriate headings as shown (Form 1 ) . Each s i t e can be systematically examined, and when any necessary soil analyses have been completed (read 13.la carefully) an objective assessment of the s i tes can be made.

Y

40. F o r m 1

POTENTIAL NURSERY S I T E

NAME OF AREA DATE

LOCAT I ON

S O I L SURVEY TYPE

TOP S O I L

1. TEXTURE ASSESSMENT 2 . DEPTH 3. DH

SUBS01 L

1. TEXTURE ASSESSMENT 2. DEPTH 3. DH

DEPTH TO WATER TABLE

DRAINAGE

WATER SUPPLY:

TOPOGRAPHY:

COVER: 1 . 2.

CL IMATIC DATA

1. 2. 3. 4. 5.

1. 3. 4.

5.

ADJACENT CREEK WELL

OTHER RISE OR FALL (FEET) TO SUPPLY

PH

LEVEL 2. ROLL I NG IRREGULAR, BUT GENERALLY LEVEL UNIFORM SLOPE:

DEGREES DOWN UNSUITABLE i .e. m o r e than 60

TO o r v . irregular

MAIN TREE SPECIES COMMON MEMBERS OF GROUND FLORA

(USE NEAREST STATION IN DEPARTMENT OF TRANSPORT TABLES) :

TOTAL ANNUAL PPTTION. PPTTION. MARCH APRIL MAY NUMBER OF FROST-FREE MONTHS

~-

HIGHEST TEMP. AND MONTH LAST YEAR

APPROXIMATE ACREAGE

ACCESS OWNERSHIP

41.

LITERATURE CITED

W ACKERMAN, R.F. and J.L. FARRAR, 1965. The e f f e c t o f l i g h t and temp- e r a t u r e on t h e g e r m i n a t i o n o f j a c k p i n e and lodgepole p ine seeds. Univ . Toronto Fac. Forestry, Tech. Rep. 5, pp. 41.

ALDHOUS, J.R. 1966. Simazine residues i n two f o r e s t n u r s e r y s o i l s . F o r e s t r y Comm. Res. Develop. Pap. 31 , pp 9.

ALDHOUS, J.R. 1968. Maintenance o f f e r t i l i t y i n f o r e s t n u r s e r i e s . F o r e s t r y Commission Res. Dev. paper 68. pp. 24.

ALDRICH-BLAKE, R.N. 1932. The i n f l u e n c e o f n u t r i t i o n o n t h e r e l a t i v e r o o t and shoot development o f f o r e s t t r e e s e e d l i n g s . F o r e s t r y 6:40-52.

ALLEN, G.S. 1 9 6 0 . F a c t o r s a f f e c t i n g t h e v i a b i l i t y a n d g e r m i n a t i o n b e h a v i o u r o f c o n i f e r o u s seed. IV. S t r a t i f i c a t i o n p e r i o d and i n c u b a t i o n temperature, Pseudotsuga menziesii (Mirb. ) Franco. Forestry Chron. 3 6 ~ 1 8 - 2 9 .

ALLISON, F.E. 1965. Decomposi t ion of wood and bark sawdust i n s o i l , n i t rogen requ i rements and e f f e c t s on p l a n t s . Tech. B u l l . U.S. Dep. A g r i c . 1332.

ARMSON, K.A. and R.D. CARMAN, 1961. F o r e s t T r e e n u r s e r y s o i l management, Ontario Dept. Lands and Forests Manual, pp. 74.

BELL, T.I.W. 1968. E f f e c t o f f e r t i l i z e r and dens i ty p re t rea tment on sp ruce seed l i ng su rv i va l and growth. Forestry Commission: Forest Record 67 pp. 35. H.M.S.O. London.

BENZIAN, B. 1965. Experiments on n u t r i t i o n problems i n f o r e s t n u r s e r i e s . F o r e s t r y Commission B u l l . 3 7 ( 1 ) pp. 251. H.M.S.O. London.

BENZIAN, B. 1966. Manuring young coni fers: exper iments i n some E n g l i s h nurser ies . Proceed ings o f the Fer t i l i ze r Soc ie ty , London. 94 :3-35 .

BIENTJES, W . 1954. The e f f e c t s o f temperature, seed moisture, and s t r a t i f i c a t i o n on the germinat ion behaviour of western hemlock seed. Univ. B-rit. Columbia Forest Club. Res. Note 11, pp. 7.

BLOOMBERG, W.J. 1965. The e f f e c t o f c h e m i c a l s t e r i l i z a t i o n on the fungus p o p u l a t i o n o f s o i l i n r e l a t i o n t o r o o t d i s e a s e o f Douglas fir seed l ings . Fores try Chron . 41 : 182- 187.

BOON, W.R. 1967. The q u a t e r n a r y s a l t s o f b i p y r i d y l - a new a g r i c u l t u r a l

BUSGEN, M. and E. MUNCH, 1929. The s t r u c t u r e a n d 1 i f e o f f o r e s t t r e e s .

t o o l . Endeavour 26 (97) : 27-32.

3 rd ed . t rans l . T. Thomson, Chapman and H a l l L t d . , London.

CONNER, B.J., and D.P. WHITE, 1968. T r i a z i n e h e r b i c i d e s and t h e n i t r o g e n n u t r i t i o n o f c o n i f e r s . Q u a r t . B u l l M ich . Agr ic . Exp. Sta. 50(4):497-503.

42.

FAULKNER, R. and J.R. ALDHOUS, 1956. Nursery invest igat ions, pp. 16-32 Forestry Commission Report on Forest Research for the year ended March , 1955. H.M.S.O. London.

FORESTRY COMMISSION 1964. Fores t ry p rac t ice . Ed. H.L. E d l i n . F o r e s t r y Comm. B u l l . 14, pp. 103, H.M.S.O., London.

HELLUM, A.K. 1968. A c a s e a g a i n s t c o l d s t r a t i f i c a t i o n o f w h i t e s p r u c e seed p r i o r t o n u r s e r y s e e d i n g . Can. Dept. For. Rur. Dev., For . B r . Publ . 1 243.

-1 INGESTAD, T. and H. NILSSON, 1964. The e f f e c t s o f s o i l f u m i g a t i o n , s u c r o s e a p p l i a t i o n , and i n n o c u l a t i o n o f s u g a r f u n g i on t h e g r o w t h o f f o r e s t t r e e s e e d l i n g s . P l a n t and So i l 20(1) :74-84 .

1 JACKS, G.V. 1954. S o i l . Thomas Nelson and Sons L t d . , London, pp. 221.

JOHNSON, L.C. and H. IRGENS-MOLLER, 1964. E f f e c t o f p h o t o p e r i o d and l i g h t q u a l i t y on germinat ion o f Douglas fir seed. For. Sci . 10( 2 ) :ZOO-205.

JONES, E.W. 1968. A note on the d imensions o f shoots and roots of p l a n t - i n g s t o c k . F o r e s t r y 41 ( 2 ) :199-206.

KORSTIAN, C.F., C. HARTLEY, L.R. WATTS, and G.G. HAHN, 1921. A c h l o r o s i s o f c o n i f e r s c o r r e c t e d b y s p r a y i n g w i t h f e r r o u s s u l p h a t e . J. A g r i c . Res. 21 : 153-1 71 .

c

W

KOZLOWSKI, T.T. and J.E. KUNTZ, 1963. E f f e c t s o f s imaz ine , a t raz ine , propazine, and eptam on growth and development of p ine seedl ings. Soi l Sci . 951164-174.

KOZLOWSKI, T.T., and J.H. TORRIE, 1965. E f f e c t o f s o i l i n c o r p o r a t i o n o f h e r b i c i d e s on seed germination and growth o f p i n e s e e d l i n g s . S o i l S c i . 100 ( 2 ) : 139-146.

KRUEGER, K . W . 1963. Compounds leached from Western red cedar sh ing le tow found tox ic to Doug las fir seed l ings . U.S. Fores t Serv . Res. P a c i f i c Northwest. For. Ran. Exp. Sta. No. PNW-7.

KRUEGER, K.W. and J.M. TRAPPE, 1967. Food reserves and seasonal growth o f Douglas fir seedl ings. For. Sci . 13:192-202.

LAVENDER, D.P., 1958. Seeding dates and Douglas fir germinat ion . S ta te o f Oregon, F o r e s t Lands Research Centre, Res. Note 34, pp. 15.

MacARTHUR, J.D. and J.W. FRASER, 1963. Low temperature germinat ion o f some eastern Canadian tree seed. For. Chron. 39(4) :478-479.

MIKOLA, P. 1959. Tutkimuksia ta in i tarhamaasta j a sen va iku tukses ta ta imien keh i tykseen (S tud ies on s o i l p r o p e r t i e s and seedl ing growth i n F i n n i s h f o r e s t n u r s e r i e s ) . Communicationes I n s t i t u t i F o r e s t a l i s F e n n i a e 49, pp. 78.

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MINSHALL, W . H . , 1969. Effect o f nitrogenous materials on the uptake of triazine herbicides. Weed Sci. 17(2) :197-201.

MULLIN, R . E . , 1966. Root pruning of nursery stock. Forestry Chron. 42 ( 3) : 256- 264.

MULLIN, R . E . , 1969. Soil acidification with sulphur in a forest t ree nursery. Sulphur Institute Jour. 5:2-3.

NEMEC, A . , 1939. Untersuchungen uber den Einfluss chlorhaltiger Kali- dungemittel auf das Wachstum und auf die Ernahrung der Fichte in Waldbaum- schulen. Bodenk. Pflanzenernahrung. 13:35-72.

RICHARDSON, S.D. 1959. Germination of Douglas f i r seeds as affected by l i gh t , temperature and gibberellic acid. For. Sci. 5:174-181.

ROMBERGER, J.A, 1963. Meristems, growth, and development in woody plants. U.S. Dept. Agric. Forest Serv. Tech. Bull. 1293, pp. 214.

SMITH, J.H.G., J . WALTERS, and A. KOZAK, 1968. Influences o f f e r t i l i z e r s on cone production and growth of young Douglas f i r , western hemlock, and western red cedar on the U . B . C . Research Forest. Univ. Bri t . Columbia, Fac. Forestry Bull. 5, pp . 57.

STONE, E . L . 1968. Microelement nutri t ion of forest t rees: a review. pp . 132-175 in Forest fert i l ization symposium. Gainesville, Florida. Publisher: Tennessee Valley Authority.

STONE, E . C . , J.L. JENKINSON, and S.L. K R U G M A N , 1962. Root regeneration potential of Douglas-fir seedlings lifted a t d i f ferent times of the year. For. Sci . , 8:288-297.

SWAN, H.S.D. 1960. The mineral nutri t ion of Canadian pulpwood species. Pulp Pap. Res. Inst . Canada Tech. Rep. 168, p p . 66.

THULIN, I . J . , G.M. WILL, a n d C . BASSETT, 1958. A p i l o t t r i a l of so i l s te r i l i za t ion in a forest nursery. New Zealand J . Forestry 7(5):88-93.

VAARTAJA, 0. 1964. Chemical treatment of seedbeds t o control nursery diseases . Bot. Rev. 30( 1 ) : 1-91 .

VAN DEN DRIESSCHE, R . 1963a. Nursery experiments w i t h Douglas f i r . Commonwealth For. Rev. 42( 3) :242-254.

V A N DEN DRIESSCHE, R . 1963b. Par t ia l s te r i l i za t ion o f Douglas f i r seedbeds with formalin and chloropicrin. Forest Sci. 9(3) :330-334.

V A N D E N DRIESSCHE, R . 1968. The des i rab i l i ty of micronutrient amendments for conifer nurseries. Brit. Columbia Forest Serv. Res. Rev. 1968:50-52.

VAN D E N DRIESSCHE, R . 1969a. Relationship between Douglas f i r seedling growth and levels of some soi 1 and tissue nutrients. Forestry Chron. ( i n press ) .

VAN DEN DRIESSCHE, R. 1969b. Measurement o f f r o s t h a r d i n e s s i n t w o - y e a r - o l d Douglas fir seed l ings . Can. J. P l a n t S c i . 49:159-172.

VAN DEN DRIESSCHE, R. 1969c . T issue nu t r ien t concent ra t ions o f Doug las fir and Si tka spruce. Research Note 47 , Brit. Columbia Forest Serv ice , pp. 42.

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WINJUM, J.K. 1963. E f f e c t s of l i f t i n g d a t e and storage on 2+0 Douglas fir and noble fir. Jour . Fores t ry 61 :648-654.

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