CITRUS

Taxonomy of Mandarin and Sweet Orange

Division: Embryophyta, Sub-division - AngiospermaeClass: Dicotyledonae Order GeranialeSub-order: Geranianeae Family RutaceaeSub-family: Aurantioedae Tribe Citrae, Genus: Citrus Sub-tribe Citrinae

Area and Production In India, citrus occupy 5.6 lakh hac with total production of 45.8 lakh tonnes It is mainly grown in Punjab, Haryana, UP, MP, Rajasthan, Maharashtra, A.P., Karnataka, Gujarat,

Assam, Meghalaya, Mizoram, Manipur and Nagaland. Mandarin is grown in maximum area and placed at first position followed by sweet oranges and

limes. In Punjab, citrus is grown in 20411 ha with production of 2.80 lakh tonnes. Kinnow alone occupy 17189 hac. The districts of Ferozepur, Faridkot, Bathinda and Hoshiarpur are famous for kinnow growing. Arid-irrigated region of Punjab i.e. Ferozepur, Faridkot, Muktsar and Mansa are suitable for sweet

orange cultivation. In Rajasthan, Kinnow is grown in Ganganagar, Bikaner and Jaipur. In Haryana, Sirsa, Jind, Hisar, Karnal and Ambala are suitable for kinnow growing.

Importance and Uses Citrus fruits contain considerable amount of vitamin C (50-60 mg/100 g). Citrus fruits are also good source of vitamin A and vitamin B1. TSS in fruit juice in most of the sweet group of citrus varies from 8-12%. Citrus fruits are taken as fresh fruits. Juice, squash, concentrate, marmalade, syrup, pickle, cocktail etc. are prepared from citrus fruits. Peel of thick-rinded citrus fruits can also be made into delicious candy.

Swingle’s system of ClassificationGenus : CitrusSubgenus Eucitrus Papeda

10 spp. 6 Spp.1. C. tachibana 1. C. ichangensis2. C. medica 2. C. latipes3. C. limon 3. C. micrantha4. C. ureticulata 4. C. celebica5. C. indica 5. C. macroptera

6. C. grandis 6. C. hystrix’7. C. paradisi8. C. aurantifolia9. C. sinensis10. C.aurantium

Tanaka system of ClassificationGenus: CitrusSub genus: ArchicitrusSection:

Papeda: 12 SPP

Limonellus: Eulimonellus: 3 sp ; Megacarpa 14 spp. Citrophorum: Citroides 5 sp, Limonoides 7 spp, Decumanoides 13 spp. Cephalocitrus: Decumana 6 spp., Intermedia: 2 Groups: 15 spp.

Aurantium : Medioglobosa 16 spp; Aurantiodes; Groups : 6 spps; Sinensiodes 7, osmocitriodes: 3 Groups : 5 spp.

Sub Genus: Metacitrus

Section: Osmocitrus: Euosmocitrus 10 spp. Psudoacrumen 1 spp Acrumen: Euacrumen: 3 spp., Mocroacrumen : 2 Groups

2subgroups : 2 Microgroup : 33 spp.

Major Citrus Species1. Mandarin groupi) C. reticulata : Sangtraii) C. unushiu : Satsuma mandariniii) C. deliciosa : Willow leaf mandariniv) C. nobilis : King of Kunembov) C. reshni : Cleopatra mandarin or Billikichlivi) C. tangerina : Tangerinsvii) C. madurensis : Calamondinviii) C. madaraspatana : Kitchli, Vadlapudi, Guntur orange2. Orange groupi) C. sinensis : Sweet orangeii) C. aurantium : Sour orangeiii) C. myrtifolia : Myrtle leaf orangeiv) C. bergamia : Bergamot orangev) C. natsudaidai : Japanese summer orange3. Pummelo–grapefruit group i) C. maxima : Chakotraii) C. paradisi : Grapefruit4. Acid groupi) C. medica : Citronii) C. limon : Lemoniii) C. jambhiri : Rough lemoniv) C. karna : Kharna Khattav) C. aurantifolia : Limevi) C. latifolia : Tahiti or Persian limevii) C. limettioides : Sweet lime1. Papeda groupi) C. inchangensis : Ichang papedaii) C. junos : Yaju of Japaniii) C. latipes : Khasi papedaiv) C. macroptera : Malenasian papedav) C. histrix : Mauritius papedavi) C. macrophylla : Alemow2. Other speciesi) C. limonia : Rangpur limeii) C. limetta : The limette of the mediterraneaniii) C. indica : Indian wild orangeiv) C. pannivesiculata : Gajanimma of India

3. Related generai) Poncirus : P.trifoliata – Trifoliate orangeii) Fortunella : Kumquat

F. margarita, F. japonica, F. crassiflora, F. hindsii

Varieties of Citrus sp. 1. Sweet Orange

A. Common group or miditerranean orangesPineapple, Jaffa, Hamlin, Valencia

B. Acidless group: Musambi, SuccariC. Pigmented group: Blood Redm, Ruby, Moro, Torocco, DoblefinaD. Naval group : Washinton Naval, Roberstan, Bahianiana.

2. MandarinA. Reticulata group : Nagpur, Coorg, Khasi mandarinB. Mediterranean or Deliciosa group: Kinnow (King x Willow leaf), Wilking, Willow leaf,

Emperior.C. Satsuma group: Ovari, Wase, Kara.D. Tangerine group: Dancy, Beauty, NaartjaE. Nobilis group : King, KunemboF. Mitis group : Calamondin, Billikichli, Cleopatra

3. Mandarin like Tangers (Tangerine x Sweet orange): Temple, Clementine.

4. Mandarin like Tangelos (Grapefruit x Tangerine) : Orlando, Minneola

5. GrapefruitA. Seeded group: Duncan, Pink Marsh, Foster, Ruby, Triumph.B. Seedless group: Marsh Seedless, Red Blush, Cecily

6. Pummelo: Chakaiya, Red Fleshed, Kaopan

7. LimeA. Acid or sour lime : Kagzi, Mexican, PalmettoB. Large fruited or Tahiti lime : Tahiti, Pond, BearsC. Mandarin like : Rangpur LimeD. Sweet or Acid lime : Sweet, Local, Palestine

8. LemonA. Eureka group : Eureka, Italian Round, Villafranca, Nepali

OblongB. Lisbon group : Bonnie, Lisbon, KennedyC. Anamalous group : Meyer, Cuban, PonderosaD. Sweet or Acidless group : Mill sweet

Citrus Hybrids1. Intergeneric hybrids

(a) Hybrids of PoncirusCitrangers : Poncirus trifoliata x C. sinensisCitrangequat : Poncirus x Citrus x Fortunella. Trigeneric hybrid Citrangedin : Citrange x C. mitis (Calamondin)Citrangor : Citrange x C. sinensis Back cross

Cicitrange : Citrange x P. trifoliata “Citrumelos : P. trifoliata x C. paradisiCitrandarin : P. trifoliata x C. reticulataCitremon : P. trifoliata x C. limonCitradias : P. trifoliata x C. aurantiumCitrumquat : P. trifoliata x F. japonica or F. margarita(b) Hybrids of FlortunelaProcimequat : F. japonica x C. aurantifolia x F. hindisiiLimequat : C. aurantifolia x F. japonicaOrangequat : C. reticulata x F. japonica x F. margarita

2. Intrageneric hybrids (Interspecific)Tangors : C. reticulata x C. sinensis

e.g. Temple, Clementine : Mostly embryonic. Tangelos : C. reticulata x C. poaradisi

e.g. Orlando, MinneolaLemonimes : C. limon x C. aurantifoliaLemonnage : C. limon x C. sinensisLemandarin : C. limon x C. reticulata

Flowering and Fruit Development Fruit growth pattern in citrus follows a simple sigmoid. On the basis of fruit weight and volume,

Kinnow fruits followed a pattern of sigmoidal growth. Citrus seeds do not have dormancy period. Always fresh seeds should be sown. Optimum temp. for

seed germination in 32oC. Most citrus species are polyembryonic and from one seed two or more seedlings may emerge. One

of these is sexual seedling and the others are nucellar seedlings which are identical with the mother plant.

C. medica, C. grandis, Temple and Clementine mandarins and Meyer lemon are monoembryonic and their seedlings are very heterogenous.

Flowering in citrus takes place mostly in spring. In limes and lemons, flowering takes place almost throughout the year. In north India, the main flowering in all citrus species takes place during early spring (February-

March). In Kinnow, flowering time in end February to early March in north India. In South India, Sathgudi oranges flower twice in a year from December-April and September to

December. Coorg mandarin have two distinct flowering periods i.e. main season flowering (March-April) and off season flowering (September-October).

In central and western India, oranges flower thrice a year at intervals of 4 months i.e. June, October and February.

The Sweet lime trees bears 2 types of flowers viz. Staminate and hermaphrodite on the same tree; but the formation of staminate flowers is more. The fruits mature about 6 months after flowering.

Grapefruit tree produce flowers and fruits once in a year under North Indian conditions in spring and fruits mature after 8 to 9 months in the months of November and December.

Honey bees are common pollinating agent in citrus. Cross pollination increase seedlings in certain citrus cultivars viz. Shamouti orange, Clementine

mandarin and Mineola tangelo. Self incompatibility has been reported in Nepali Oblong and Lucknow Seedless lemon, pummelo

Clementine mandarin and sweet lime.

Climate Citrus is sub-tropical fruit. Temp. 0 to –2oC is injuries to citrus fruits.

Extremely high temp. is not conducive – leads to sun burning.Sweet Orange Dry and arid conditions coupled with wall defined summer and winter season having low temp. are

most suitable conditions. In north India, it is grown best under irrigation in the plains of Punjab, Rajasthan and Western UP

where summer and winter are more markedly severe and much drier. Rainfall varies from 20-75 cm from June to Sept.

Mandarin Sub-montane tracts 600-1100 m & rainfall 75-250 cm is ideal. Nagpur region with 300-360 m elevation, rainfall 111 cm., R.H. 53%, highest maximum temp. 47oC

& lowest minimum temp. 6oC are best. Kinnow growing in Punjab, H.P., Rajasthan doing well in warm cool temp. with chilling temp.

resulted economical cropping & excellent quality fruit.

Soil Citrus fruit trees are very sensitive to high salt conc. in the soil. Salt toxicity shows leaf burn symptoms. EC in soil should be less than 2 mmhos/cm.Sweet Orange Soil should be medium to light loam, rich in organic matter, well drained. PH 6-8. Soil should be atleast one metre deep. Mandarin Well drained, light loam to loam soil is preferred. Water table should be below 3 m, have no hard pan within 2 m. PH 5-8. In Nagpur region soils are coarse, free working, well drained, black, loamy, 6’ deep. In general for citrus PH should be up to 8.5, EC 0.5 mmhos/cm, free lime < 5%, lime concretion <

10%.

Propagation Raising of Rootstock Jatti Khatti, Cleopatra for Blood Red and Pectinifera for Musambi. Kharna Khatta, Troyer, Carrizo, Rangpur lime, Citrumelo are also used. Seeds of citrus sp are polyembryonic, thus nucellar seedlings are used for raising uniform seedlings. Immerse seeds in hot water at 52oC to check phytophthora.

Selection of Scion. Should be virus free bud wood, from known pedigree.Time and Method of Propagation: Mandarin, Sweet orange & grapefruit are propagated through T-budding in February-March and

August-September. Lime & lemon are propagated through Air-layering or semi-hard wood cuttings during

February-March and August-September. Sexual method is used in lime.

Planting Citrus is planted twice in a year i.e. spring season (February-March) and rainy season (August-

September). August-September planting is considered best as the weather has cooled down sufficiently. Spacing commonly given to citrus plants in north India is 6x6 m in square system and accommodate

275 plants per hectare. Kinnow is being planted as 20’x22’, 10’x11’, 15’x15’, 17’x17’ and 20’x15’ and also as a filler tree

in mango, pear and litchi. Young plants must be protected against high and low temperature and strong winds. Young plants are susceptible to frost and must be protected during first two winters.Cultural PracticesIrrigation

Water requirement of lemons is maximum followed by grapefruit, mandarins and sweet orange in discending order.

In Kinnow and other citrus trees water stress cause twig die back, leaf and fruit drop, lower fruit set and reduction in fruit size.

Active growth of citrus plants and fruit takes place from March to June. Also weather becomes increasingly hot and remains generally dry during this period.

March to June is critical period and period of peak water requirement for citrus orchards. Utmost care should be given to irrigation during this period.

Young citrus orchards up to 8 years should be irrigated by basin system. Under north Indian conditions weekly irrigation during March to June and fortnightly irrigation

during November to February are followed. Citrus trees are highly sensitive to excessive moisture and water-logging conditions. Excessive irrigation may result in poor soil aeration leading to reduced growth and yield. As citrus plants are very sensitive to saline and alkaline conditions. The total soluble salts in the

irrigation water should not exceed 1000 ppm.

Weed Management In the second fortnight of March after the emergence of weeds spray Glycel 41 SL (Glyphosate) @

4l/ha followed by glycel 41 SL or gramoxone 24 WSC (Paraquat) at 3 l/ha in the second fortnight of July in 500 litres of water in Kinnow orchards.

Intercropping Intercrops can be taken before the trees become productive. Exhaustive inter-crops like cotton, chari, bajra, barseem, maize, bhindi, and creeper type vegetables

should not be grown in the orchards. In young orchards, up to 4 years of age, leguminous crops such as guara, moong, mash, cowpea,

gram and pea may be grown. In sweet orange orchards, guara and wheat can be grown in rotation with guara as green manure for

first 5-6 years. Sufficient space should be left unsown around young trees to ensure their unrestricted growth. Additional fertilizers should be added to meet the requirements of the intercrop and fruit trees and

intercrop should be provided independent irrigation systems. Barseem require frequent irrigation in winter season, it leads to phytophthora attack in citrus

orchards.

Nutrient ManagementAccording to Chapman, 18 tonnes of citrus fruits remove nutrient as follow.N 21 Kg, P 5 Kg, K 41 Kg, Ca 19 Kg, Mg 3.6 Kg, S 2.3 Kg, Bo 40g, Co 9 g, Fe 50 g, MN 13 g, Zn 13 g.

Nitrogen deficient trees show general lightening of green part of leaves. Leaves turn yellowish green. Trees become stunted, sparse foliage, produce dead wood, bear little fruit.

Potassium deficiency resulted reduced growth and smaller leaves. New growth very weak, twigs break easily. Fruits remained small, have thin, smooth & well-coloured rind.

Magnesium deficiency appear in old leaves when fruit is mature. Chlorotic spots at the tips & between the vein. Leaves become abnormally thin.

Zinc deficiency appear on fully mature new leaves.

Irregular interveinal chlorosis in leaves – Mottled leaf. Terminal leaves become small & narrow – Little leaf. Fruit bud formation severally reduced, twigs die back.

Manganese deficiency occur as green veins on light green background. Bands develop along mature leaves with light green tissue.

Iron. General chlorotic condition of the areas between the veins. Later on areas between the veins become yellow. Premature defoliation, twigs dying back starts.

Fertilizer Schedule Recommended by PAUAge of tree (Years) FYM (Kg/tree) N (g/tree)1-3 5-20 50-1504-6 25-50 200-2507-9 60-90 300-40010 and above 100 400-800

FYM in Dec., N ½ in Feb, ½ in April-May (After fruit set)In Maharashtra – For Mosambi (Sweet Orange)N – 800g, P-100 g, K-400 g.Zn deficiency correction: 0.3% ZnSO4, April, June, September without lime. 0.45% ZnSo4 if deficiency is acute.

Training and Pruning In young citrus orchards staking should be done to ensure upright growth of trees. Citrus trees do not require pruning except removal of unwanted, intercrossing, diseased and dead

branches. Pruning is generally done in the spring after the danger of frost has passed and before new growth

starts. In Kinnow, water sprouts are a common phenomenon. These are characterized by sparse foliage and

large thorns. They bear profusely fruits of poor quality. Trees under water stress produce water sprouts in abundance upon removal of stress, generally in

rainy season. Water sprouts should be pruned judiciously to balance them with the rest of trees.

Thinning of fruits Young Kinnow trees of 3-4 years old tend to produce heavy crop. Taking heavy crop during initial years impairs tree health. Hand thinning of floral buds and fruits should be done. Usually fruit thinning is done in May soon

after fruit set. Crop should be so regulated that flushing continues throughout the year.

Harvesting and Fruit Handling Citrus fruits should be harvested when they are fully ripe as they are non-climacteric in nature. Citrus fruits develop their characteristics flavour and aroma at fully ripe stage. Fruits do not at all improve in quality after they have been harvested from the tree. TSS : Acid ratio is a scientific and reliable index for adjusting maturity of citrus fruits. Best harvesting time of Kinnow mandarin on Jatti Khatti fall between 20th January to 9th February.

Optimum harvesting time of fruits and varieties of citrus grown in PunjabKind/Variety Harvesting time Solids/acid ratio1. Sweet OrangeMusambi November 30:1Pineapple and Jaffa December 14:1Blood Red December-January 14:1Valencia February-March 10:1

2. MandarinsKinnow Mid Jan.-Mid February 12:1 to 14%Local December-January3. GrapefruitRed Blush November 6:1Foster November-December 6:1Marsh Seedless December-January 7:1Duncan January 6:14. Lemon August-November

Harvesting in early hours of the day when there is a heavy dew on the fruits or immediately after rains should be avoided.

Harvesting should be done with clipper by retaining a non-protruding short fruits stalk (button). Full grown sweet orange tree yield 500-1000 fruits. Well grown up Kinnow tree of about 10-12 years of bears about 1000-2000 fruits.

Grading and sizing of fruits Fruits of mandarin and sweet oranges can be graded into 4 categories.i) Extra special : With minimum diameter of 8.1 cm.ii) Special : With minimum diameter of 7.5 cm.iii) Good : With minimum diameter of 6.8 cm.iv) A : With minimum diameter of 6.2 cm.

Fruits can be packed in boxes in 3 or 4 layers.

Post-harvest handling Proper stage of maturity is the prime factor for harvesting Kinnow fruit for storage. Fruits harvested too early or late in the season do not keep well in the storage. Little spoilage occurs by dipping kinnow fruits in 125 ppm Benlate for one minute, drying them in

air followed by wrapping in 100 gauge perforated polythene bags. Kinnow fruits can be stored up to 85 days at 0-3o-3o temp. and 80-90% relative humidity. Healthy unbruised Kinnows harvested during first week of February can be stored for 8 weeks at

prevailing room temperature by individually seal packing with electric sealer or rubber band in 10 micron thick high density polythene bags.

Larger sized Marsh grapefruits store better than the small sized fruits at room temperature. These can be stored for 60 days at 15-20oC.

Treatment of harvested fruit with GA3 @ 30 ppm and wrapping in polythene bags (100 gauge) considerably improve the storage life.

Problems in cultivationFruit drop Citrus trees bear large number of flowers and fruits, all of which they are unable to carry to maturity.

Not more than 7-8 per cent flowers develop into mature fruits. The fruits drop in three definite waves. Initially unfertilized flowers and flowers with defective ovules fall. In second wave fruits drop in May-June due to water stress and also those with defective ovules. These two waves are not of much significance, as only under-developed fruits drop. The last wave of fruit drop, known as pre-harvest drop, occur just before fruit mature. It reduces

yield considerably, moreover fully grown fruits drop which have drawn full nutrition and exhaust the tree.

There are two main causes of fruit drop i.e. physiological and pathological.

Physiological fruit dropCauses : Climatic factors

: Disturbed water relations: Nutritional factors: Relation of seed to fruit drop.

Physiological fruit drop is primarily due to the formation of an abscission layer at the point of attachment of the fruits with twigs.

This abscission layer form due to growth regulation imbalance within the tree.Control

Spray 2,4-D (sodium salt of horticultural grades) 10 ppm in September to check physiological fruit drops.

Do not spray 2,4-D, when dicot crop is inter-cropped in citrus orchard.

Pathological fruit dropCauses

Styler end rot. Stem end rot. Maximum Pathological fruit drop occur due to stem end rot and it is caused by Colletotrichum

gloeosporioides and Alternaria citri. Symptoms

Dark circular depressions with yellowish margins on leaves, branches and fruits appear. Later the spots become raised, rough and light brown.

Leaves and fruits acquire sand paper texture.Control

Sten-end-rot can be checked by spraying Bavistin 0.1% or Aureofungin 20 ppm or Bordeaux mixture (2:2:250) at 15 days intervals after four months of fruit set.

Insect-Pests of Citrus1. Citrus Psylla Active during mid April to mid October. Nymphs and adults suck the cell sap from buds, leaves and young shoots. Leaves gets curled and

shoots starts drying. Act as vector of greening disease.

Control Spray 625 ml Nuvacron or 1250 ml Rogor or 1000 ml. Metasystox in 500 litres of water in second

week of March and again in first week of September

2. Citrus leaf miner Active during April-May and September-October. Larvae attack the tender leaves/shoots epidermis by making serpentine mines which are silvery in

colour.

Encourage development of citrus canker.Control

Spray 625 ml Nuvacron or 250 ml Sumicidin or 500 ml Ripcord or 1750 ml Decis at 15 days intervals during flushing period in 500 litres of water.

3. Leaf folder Active during May to October. Larvae feed inside the leaves by webbing them together and start feeding from top to downwards. Plants become stunted.

Control Spray 625 ml. Nuvacron or 1250 ml. Dursban or 1000 ml. Ekalux in 500 litres of water.

4. Citrus whitefly Active from March to November. Both nymphs and adults suck the cell sap from tender leaves and shoots and reduce the vigour of

plant.Control

Spray 1140 ml Thiodan or 1000 ml Fosmite or 1250 ml Hostathion in 500 litres water during April-May and September-October.

5. Mites Active during May-June of August-September. Damage leaves, flowers and fruits.

Control Spray Rogor 670 ml in 500 litres of water.

1. Bark eating caterpillar Bore holes into stem and branches and feed on the bark under the cover of its excreta.

Control Remove webbing and inject kerosene oil into the holes during September-October and January-

FebruarySpray Schedule: February-March ) 625 ml Nuvaron or 670 ml Rogor in 500 litres of water. May-June ) July-August ) April ) 1000 ml Thiodan in 500 litres of water.

Citrus diseasesSymptoms Casual

organismControl

1. Canker Yellowish spots appear on

leaves which enlarge, turn rough & brownish and become raised on both sides of leaf.

Fruits lesions become rough and corky.

Xanthomonas campestris pv. Citri

Spray 50 g streptocycline and 25 g CuSo4 in 500 l/water in Oct. , Dec., and Feb. or Bordeaux mixture (2:2:250) or 50% cooper oxychloride (0.3%)

2. Scab Small, dark brown, rough,

irregular, raised besions on

Elsinoe fawcetti 3 sprays of Ziram (0.25%) or Dithane–45 (0.25%) or Bordeaux mixture (2:2:250) or 50% Co.

underside of leaves. Twigs and fruits are also

affected.

oxychloride (0.3%) during last week of June to August at 20 days interval.

3. Gummosis (Foot Rot): Profuse gumming, trunk

girdling, pale green foliage, stunted growth, flushes and twig die-back. Gummy lesions may also appear on branches/limbs.

Phytophthora Palmivora

Decortication and disinfection of wounds on trunk with disinfectant soln., cover wounds with B. paste, apply B. paint and spray B.M.2:2:250 or Treat twice with Ridomil MZ as paint to( 2 g.in 100 ml. of linseed oil) trunk and drench (25 g in 10 l/water) soil at base of tree in February-March & July-August.

4. Whither Tip Drying of tips and branches

and even large limbs. Necrotic circular areas on leaves. Fruit rot

Colletotrichum gloeoporioides Or Physiological causes

Remove infected twigs during February and spray with B.M. (2:2:250) or 50% Co.oxychloride (0.3%) during March, July and September.

5. Melanose or stem and fruit rot.

Dark circular depressions and yellow margins on leaves, branches and fruits.

Phomopsis citri Spray B.M. (2:2:250) or 50% Co.oxychloride (0.3%) during July-August and September.

Citrus Decline It may be due to several causes, such as unhealthy planting material carrying viruses and similar

diseases, improper rootstock, defective soil, poor drainage, mis-management of the orchard, malnutrition, insects, nematodes and diseases.

1. Virus and Virus like diseases

Greening: Stiff, upright multiple twigs and buds, small chlorotic or mottled leaves. Pre-mature defoliation. Die back of branches

Tristeza: Veinlet clearing in young leaves. Nacrosis of cells at bud union. Honey combing of main stem. Inverse pits on bark.

Exocortis: Yellow blotch & cracks on shoots with stunting of trees.

Ring Spot. Yellow ring on mature leaves. Rings coalesce to form bigger patch. Dieback and decline of plant. Virus transmitted through infected bud-wood.

Bacterium

Viroids

Use disease free bud-wood. Control insect vectors citrus

psylla.

Use disease free bud wood and tolerant rootstock Jatti Khatti.

Check vector Aphid.

Use disease free bud wood and tolerant rootstock Jatti Khatti. Sterilise cutting tools.

Use virus free plants.

For the rejuvenation of declining citrus orchards, the following schedule is recommended: Remove dead wood during January-February before the new growth starts. Spray 2:2:250 Bordeaux

mixture immediately and apply Bordeaux paste to the cut surface and the trunk of the trees. Apply Bordeaux paint to the trunk after a week.

Add recommended doses of manures and fertilizers. Spray the solution containing 1.5 kg of zinc sulphate in 500 litres of water and Bordeaux mixture

separately (there should be a minimum gap of one week between the two sprays) in April, June and September or on new growth flushes when the leaves have attained two-third of their size.

Follow the recommended spray schedule against pests and diseases.

Granulation Granulation is a pre-harvest physiological disorder of citrus fruits. Juice vesicles dry up and become hard. Their colour becomes greyish. In affected vesicles pectin, legnin and other polysaccharides increase and TSS, sugars, acidity and

juice percentage decreased considerably. Sweet orange cultivars such as Musambi, Hamlin, Blood Red are much more prone to this disssorder

than mandarins. In general, environmental conditions that promote vigorous vegetable growth result in higher

incidence of granulation.Factors affecting granulation

Climate Species and cultivars. Rootstocks. Mineral nutrition. Plant growth regulators. Crop load Location of fruit on tree

Control Early harvesting of crop, as granulation become severe with advancement of maturity. Restricted amount and frequency of irrigation should be given. Spray of lime, zinc sulphate and Bordeaux mixture reduce incidence of granulation. Spraying of 2, 4-D, GA and NAA reduce incidence of granulation. Lead arsenate spray at 250-500 ppm reduce granulation.

Kinnow

Mosambi

Foster

Jaffa

Red Blush

Sweet lime

Kinnow

Local Mandarin

Galgal

HDPE Packaging in Citrus