Upper Leaf Necrosis in Upper Leaf Necrosis in Oriental Hybrid LiliesOriental Hybrid Lilies

William B. Miller and Y.-C. (Alex) ChangWilliam B. Miller and Y.-C. (Alex) ChangDepartment of HorticultureDepartment of Horticulture

Cornell UniversityCornell University

..

How do ULN symptoms develop?

1st day symptoms visible

21 days later

28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 460

5

10

15

20

25

Days after planting

Crop 1, 91 necrosed plants

Crop 2, 85 necrosed plants

Crop 3, 83 necrosed plants

When does ULN occur?

Most plants begin to show symptoms 30-40 days after planting

% N

ecro

sed

Pla

nts

Where do ULN symptoms occur?

ULN only occurs on leaves associated with flower buds and the leaves immediately below the buds

Macronutrients (%)

P K Ca Mg

Healthy 0.31 b 2.33 b 0.57 a 0.19 a

Necrosed 0.44 a 3.36 a 0.10 b 0.16 b

Micronutrients (ppm)

Fe Mn Cu B Zn Mo Ni

Healthy 98.4 a 32.6 a 6.04 a 26.8 a 55.4 b 0.12 a 1.23 a

Necrosed 62.2 a 22.1 b 2.67 b 22.1 a 70.7 a 0.17 a 0.63 a

Tissue analysis Tissue taken at this ULN stage

1 23

45

0

0.1

0.2

0.3

0.4

0.5

0.6

0.7

0.8

0.9

0 1 2 3 4 5

Necrosis Index

The hypothesized cause of ULNThe hypothesized cause of ULN

ULN is a calcium deficiency disorder: Leaf overlap reduces

transpiration, thereby reducing Ca transport to the young leaves, thereby encouraging the symptoms

Also due to insufficient Ca supply from the bulb

CalciumCalcium

Calcium moves upward in plants with the water flowCalcium moves upward in plants with the water flow Xylem (water-conducting) systemXylem (water-conducting) system Calcium accumulates in leaves that are actively losing water Calcium accumulates in leaves that are actively losing water

through transpirationthrough transpiration Young or “congested” leaves don’t transpire as muchYoung or “congested” leaves don’t transpire as much Leaves (or fruit) that grow faster than their calcium supply are Leaves (or fruit) that grow faster than their calcium supply are

susceptible to calcium deficiency problems (e.g. blossom end susceptible to calcium deficiency problems (e.g. blossom end rot in tomato)rot in tomato)

Bulb Scales

0

0.02

0.04

0.06

0.08

0.1

0.12

0.14

0.16

0.18

0.2

0

2

4

6

8

10

12

14

16

18

0

2

4

6

8

10

12

14

16

18

0 10 20 30 40 50 60 70

Days after planting

0

0.5

1

1.5

2

2.5

3

0

20

40

60

80

100

120

140

160

0

1

2

3

4

5

6

0 10 20 30 40 50 60 70

Days after planting

All Leaves

Folded (young) Leaves

0

0.05

0.1

0.15

0.2

0.25

0.3

0.35

0

0.1

0.2

0.3

0.4

0.5

0.6

0.7

0

0.1

0.2

0.3

0.4

0.5

0.6

0.7

0 10 20 30 40 50 60 70

Days after planting

Table . Effect of fertilizer calcium levels on upper leafnecrosis on Lilium cv. Star Gazer. n=16.

Calciumlevel(mM)

Necrosis

Incidence (%) Severity

Flower budabortion

(%)

4 (control) 12.5 z 0.1 cy 0 z

0.2 75.0** 4.1 b 0NS

0.0 100.0** 40.9 a 100**

0 mM Ca 0.2 mM Ca 4 mM Ca

Sand cultures…14/16 cm bulbsSand cultures…14/16 cm bulbs

Ca-free nutrient solution reproduced ULN symptoms

0 1.2

53.3

0

10

20

30

40

50

60

12/14 cm 14/16 cm 16/18 cm

Bulb size

Nec

rose

d p

lan

ts (

%)

Larger bulb sizes increase ULN

12/14 cm 16/18 cm14/16 cm

Bulb size vs. leaf enclosure (“apical congestion”)

Artificial Leaf UnfoldingArtificial Leaf Unfolding

Table . Effect of artificial unfolding on reducingupper leaf necrosis on Lilium cv. Star Gazer.n=30.

Unfolding frequency(times/day)

Necrosis

Incidence (%) Severity

Control 86.7z 15.1ay

1 3.3** 0.47 b

2 0.0** 0.00 b

Artificial Leaf UnfoldingArtificial Leaf Unfolding

1X/dayControl 2X/day

Overhead fans to blowing down

Overhead fans to reduce ULN

Fan off Fan-low Fan-high

Adding calcium to bulbs before plantingAdding calcium to bulbs before planting

A range of studies, using several Ca concentrations and A range of studies, using several Ca concentrations and dipping times (1 min to 16 hours) were conducteddipping times (1 min to 16 hours) were conducted

Basic conclusion: no positive effectBasic conclusion: no positive effect

NecrosisCalciumchloride

concentration(mM)

Dippingtime

(hour)Incidence

(%)Severity

Lethalcalciumdamage

(%)

0 16 92.9 12.8 0.0200 1 92.9 12.3 0.0200 4 100.0 14.2 3.6200 16 81.5 12.3 0.0400 1 92.9 13.2 0.0400 4 85.2 14.0 3.6400 16 84.0 12.7 10.7

Effectiveness of bulb dips in calcium chloride on upper leaf necrosis on Lilium cv. Star Gazer.

Upper Leaf Necrosis is a calcium deficiency disorder:Upper Leaf Necrosis is a calcium deficiency disorder: Insufficient Ca supply from the bulbInsufficient Ca supply from the bulb

Insufficient transpiration resulting from leaf enclosure of the Insufficient transpiration resulting from leaf enclosure of the

shoot apexshoot apex

Necrosis symptoms begin to show 30-40 days after plantingNecrosis symptoms begin to show 30-40 days after planting

This is when plants are about 12” tall This is when plants are about 12” tall

The 5 leaves immediately below the flower buds and the leaves The 5 leaves immediately below the flower buds and the leaves

associated with the buds are most susceptibleassociated with the buds are most susceptible to ULN to ULN

Actual injury occurs much earlier than symptom Actual injury occurs much earlier than symptom

expressionexpression

Conclusions

Factors that increase ULN:Factors that increase ULN: Larger bulbsLarger bulbs Low transpirationLow transpiration

High humidity (mist)High humidity (mist)

Horticultural methods to reduce ULN:Horticultural methods to reduce ULN: Use smaller bulbs if applicableUse smaller bulbs if applicable

Keep greenhouse “dry”Keep greenhouse “dry”

Prevent water accumulation on leavesPrevent water accumulation on leaves

Supplemental lighting in winterSupplemental lighting in winter

Daily foliar Ca sprays (days 25-45)Daily foliar Ca sprays (days 25-45)

Bulb dips are not promisingBulb dips are not promising

Airflow! Overhead fans offer a promising method to control ULNAirflow! Overhead fans offer a promising method to control ULN

Conclusions

Acknowledgements Acknowledgements

USDA/ARS-SAF National Floriculture Research USDA/ARS-SAF National Floriculture Research Initiative Initiative

Fred C. Gloeckner Foundation Fred C. Gloeckner Foundation Royal Dutch Wholesalers Association for Flowerbulbs Royal Dutch Wholesalers Association for Flowerbulbs

and Nursery Stock and Nursery Stock Post/Schenkel Memorial CouncilPost/Schenkel Memorial Council Ministry of Education, TaiwanMinistry of Education, Taiwan