CLIMATE AND SOILS

Climate

Tropical climate with moderate annual rainfall of i.e., 750 mm are ideally suited to Sweet orange and Acidlime. They can be grown successfully even upto an elevation of 900m above mean sea level and the best growth performance occurs around temperature of 320C.

Soils

A well drained loamy soil of uniform texture upto depth of 2-3 m having good fertility is considered ideal for cultivation. The plant is highly sensitive to waterlogged situation. Heavy soils, if well drained, yield good crops but the cultivation becomes difficult. Soil pH of 6.5 to 7.5 ideal.

VARIETIES

Sweet Orange

Sathgudi

This variety is a high yielder (16-18t/acre) and popular in South India because of wider adaptability and better consumer acceptance. The fruit is almost spherical in shape with smooth, thin, semi glossy, finely pitted rind and orange coloured when fully mature. Fruit weighs 140 to 150g. It has 10 to 12 segments, 10-14 seeds, 49% Juice, 8.5o to 9o Brix, 0.65% acidity and 47mg of ascorbic acid in 100g of juice.

Batavian (Bathayi)

Batavian variety closely resembles Sathgudi. It develops yellow patches on green background when it is basked to protect itself from fruit sucking moth and mostly grown in coastal districts of Andhra Pradesh.

Mosambi

The fruit develops prominent furrows on skin and a circular grove at the stylar end. It is having rough and thick skin and tastes sweeter and has more seeds compared to Sahgudi orange. It lacks flavour and sometimes it can be almost insipid due to unbalanced sugar acid ratio. The fruit is spherical and weighs about 200g with brix 8.5O, acidity 0.44% and juice content 43%. It is found to grow well and produce yields equal to Sathgudi.

Acid lime

The variety commonly grown in the State is Kagzi lime which is susceptible to canker. Canker tolerant varieties Balaji (Citrus Research Station, Tirupati) and Petlur selection-1 (Citrus Research Station, Petlur) were developed.

PLANTING

Planting material

Healthy and vigorously growing budlings budded on Rangpurlime root-stock from a certified nursery have to be selected. Virus free budlings of sweet orange cv. Sathgudi are being multiplied on Rangpurlime root stock and supplied to the growers from Citrus Research Station, Tirupati. In case of acid lime, 6-8 months old Canker tolerant seedlings of Balaji and Petlur Selection-1 are preferred for commercial plantations.

Spacing and Planting

Pits of 1 meter cube are dug in square system at a spacing of 6 m for both sweet orange and acidlime and filled with a mixture of top soil, 50 kg farmyard manure and 1 kg SSP. Dusting with 30g of 2% Methyl Parathion in the inner side of the pit prevents termite infestation. Planting of budlings and seedlings is done during July to December with the help of marking board. While planting care should be taken to see that the bud-joint should always be above the ground level. The plants should be watered and staked immediately after planting to avoid wind damage.

MANURING

Manures and Fertilizers

It is recommended that 50% of Nitrogen should be applied in the organic form (25 % FYM and 25% oil cakes) and the remaining 50% in the form of chemical fertilizers. Manures are applied in two equal split doses i.e. first dose in December-January, second dose in June-July. Fertilizers are applied in a circular band at a radial distance of 120 cm from the tree trunk region. Deep placement or application of fertilizers at two to three areas in a basin should be avoided. In fact, the maximum activity in sweet orange plantation was found within a depth of 25 cm and in acid lime they are more surface oriented, 80-95% being located in top 10cm.

In pre-bearing orchards micronutrient disorders are controlled by a composite spray of the micronutrients given below on new flush.

  • Zinc sulphate … 5g
  • Copper sulphate … 3g
  • Magnesium sulphate … 2g
  • Ferrous sulphate … 2.5g
  • Manganese sulphate … 2g
  • Borax … 1g
  • Lime … 6g
  • Urea … 10g
  • Water … 1 lit

In bearing orchards soil application of Zinc Sulphate @ 200g, Ferrous Sulphate @ 150g, Manganese Sulphate @ 200g, Magnesium Sulphate @ 300g and Borax @ 80g mixed with 40Kg of FYM per plant is recommended in two split doses once in two years in case of severe micronutrient disorders.

Integrated nutrient management (INM)

Soil application of 75% RDF along with AM at 500g /plant+ PSB at 100 g/plant + Azospirillum at 100g /plant and T. harzianum at 100 g/plant was found to be a sustainable solution for increased production as well as fruit quality in sweet orange. The treatment has also given the highest cost benefit ratio (2.25) there by reducing the fertilizer input cost.

Irrigation

Irrigation water containing chlorides less than 150-200 ppm, EC less than 0.25 mmhos/cm and SAR less than 8 is considered safe for irrigation. Flowering and fruit maturity stages are the most critical stages of irrigation. Irregular intervals of irrigation not only causes fruit drop but also increases the incidence of dry root rot disease.

Drip irrigation provides adequate soil moisture for optimal growth and production using only about 12-16 inches of water per acre per year. Single lateral line per row should provide adequate water for 3-4 year old orchard after which an additional line would be needed to meet the increased water requirement in older orchards.

Fertigation

Application of 75% recommended dose of nitrogen [1125 g/plant] and 300 g potassium per plant through drip irrigation at 15 days interval in the form of urea and Muriate of potash each at 46.88 g and 12.5 g/plant/application is found to increase yield by 2.02 t/ha in sweet orange Cv. Sathgudi over control. There is a saving of 25% of nitrogen [226.22kg urea] and potassium [46.43kg muriate of potash] per hectare over conventional method of applying 100% recommended dose of fertilizers to the basins.

Recommended fertilizer levels for Sweet orange and Acid lime

Age of the plant

Sathgudi  Sweet orange / plant

Acid lime

N
(g)

P2O5
(g)

K2O
(g)

FYM
(Kg)

Neem
Cake
(Kg)

Urea
(g)

SSP
(g)

MOP
(g)

N
(g)

P2O5
(g)

K2O
(g)

FYM
(Kg)

Neem cake
(Kg)

Urea
(g)

SSP
(g)

 

MOP
(g)

1st year

300

70

80

20

1.5

350

450

150

375

150

200

20

2.0

400

1000

350

2nd year

600

140

160

25

3.0

650

875

300

750

300

400

40

4.0

800

2000

700

3rd year

900

210

240

30

5.0

1000

1300

450

1125

450

600

60

6.0

1200

3000

1000

4th year

1200

280

320

35

6.5

1300

1750

600

1500

600

600

80

8.0

1600

4000

1500

5th year

1500

350

400

40

8.0

1650

2200

750

1500

600

800

80

8.0

1600

4000

1500



CULTURAL PRACTICES

Purning and Taining

In pre bearing orchards the plants should be trained to grow straight and to build a strong frame work. Root-stock sprouts, water suckers and dead wood should be removed periodically and the cut ends are smeared with 1 % Bordeaux paste. Never prune the plants during monsoon and wet climates.

Intercrops

During pre bearing period short growing leguminous inter crops like cowpea, field bean, black gram, green gram, Bengal gram, cluster bean and cucurbitaceous vegetables (except solanaceous crops) can be profitably grown in the inter spaces.

Intercultivation

Shallow ploughing may be taken up during monsoon season to avoid damage to fibrous root-system. Weeds are the major problem in the cultivation of sweet orange and acid lime. Application of post emergence weedicides like Glyphosate @ 8mℓ/ℓ or Gramoxone @ 5mℓ/ℓ along with 10 g of Ammonium sulphate is more economical than hand weeding.

Control of Fruit drop

Early and pre-harvest fruit drop is common in citrus fruits. To control this physiological disorder, it is a better to give three sprays of 2,4-D at 10 ppm (1g/100ℓ), one at the time of flowering, the second one month after fruit set and the third one month before harvest which is beneficial and increases the yield considerably minimizing the fruit drop .

Bahar Treatment

There are three flushes Ambe bahar (Dec-Jan),Mrig Bahar (June-July), Hastha Bahar (Sept-Oct) in sweet orange. The Hastha Bahar crop comes to harvest in summer and gets renumerative price. Stress period of 20-25 days is sufficient for induction of flowering under AP conditions. Main season of Bahar is August-September which comes to fruiting in March which is having very good market price. The second season practiced for Bahar is Nov-Dec where fruits comes to harvest in the months of July-august.

Harvesting

Bearing starts from fourth year onwards in Sweet orange and acidlime. The sweet orange in South India produces two crops a year regularly with a variable third crop. Main harvest is from August –September and second one from March- May. Spraying of Potassium Nitrate @ 5-10gm/ℓ at marble size and one before harvest not only improve improve the fruit size but also juice content and smooth shiny rind. Average yield in Sweet orange is 16-20 t/acre (1200-1600 fruits) and acid lime is 12-14 t/acre (3000-5000 fruits/ tree).

PESTS

Leaf miner (Phyllocnistis citrella)

The caterpillar mines into the leaves of young flush, showing glistening and zig zag mines on them. The affected leaves curl, deform and the plant appears sickly. The entire life cycle of the insect takes 2 to 7 weeks to complete, depending on temperature and weather conditions. The pest will be active during June, July and Nov- Jan months.

Control

Spraying with azadirachtin (1%) @ 10 ml/ l immediately after the appearance of new foliage and 2nd spray after a week period with chemicals thiamethoxam 0.3g + Dichlorovos 0.5ml or thiomethoxam 1ml or NSKE 5% + dichlorovos 0.5 ml or imidacloprid (confidor 100 SL) 0.5 ml or profenophos 2 ml per liter of water was recommended. But care should be taken that the same chemicals should not be sprayed repeatedly. Removal of water shoots which serve as off season source of survival.

Citrus butterfly (Papilio demoleous)

The caterpillar damage is severe in nurseries and young plantations. The larva is dark greyish brown in colour with whitish oblique patches when young, but later turns to dark green colour at later stages. These larvae feed voraciously on young foliage leaving away only the mid veins and causing severe damage.

Control

Spraying of Botanicals like Bacillus thuringiensis (dipel) 1g or 5% NSKE + dichlorovos 0.5 ml of or Rinaxipyr 0.2 ml or novaluron 0.75 ml or flubendamide 0.1 ml / L of water is recommended. Generally larval parasitoid (Distatryx papilionis) activity will be high from August to December months. Hence during these months sprayings with botanicals is recommended.

Bark and Stem borer (Indarabela tetraonis)

The caterpillar bores into stem and branches and forms long galleries of silk overlaid with small fragments of wood and fross. The larvae feed on the bark making silken galleries beneath the bark. The affected branches dry and sometimes entire plant may die.

Control

The wooden particles, silk and bored holes plugged with excreta should be cleaned and poured with dichlorvos or malathion or kerosene or petrol @5-8ml/hole using an ink pillar. Then the hole is sealed with clay so that the larva dies within the tunnel.

Green mite (Olygonychus citri, Tetranychus spp.)

Nymphs and adults lacerate the tissues and suck sap from leaves and fruits. Small white spots can be seen both on leaves and fruits. Leaves may later dry off and fruits size reduced.

Control

Spraying of wettable sulfer 3g or propargite 1 ml or dicofol 2 ml or ethion 1 ml or spiromesifin 1ml/L of water 2 times at 10 days interval is recommended for mite control. Water stress often aggravates mite problem.

Rust mites(Phyllcoptruta oleivora)

The mite nymphs and adults suck sap from tender fruits and cause light brown /grey discoloration. This discoloration is called ‘Mangu’. The mangu fruits are hard, brittle and unattractive. Thus reduces the market value of the fruits.

Control

Spraying with wettable sulfer 3g or Ethion 1 ml or ropargite 1 ml or dicofol 2 ml /L of water at button stage, marble stage and lemon sized fruiting stages as prophylactic treatment is recommended. Spraying of chemicals after appearance of symptoms is of no use.

Fruits sucking moths (Eudocema materna, E.fullonica, E.ancilla Achoea janata,)

These moths pierce the ripening fruits and suck juice. The affected fruits rot and drop. The moths will be active during dusk. The larvae develop on the weeds.

Control

  • Rotten and fallen fruits attract the adult moths. So affected dropped fruits should be collected and destroyed.
  • Destruction of weeds like Cocculus pendulus, C. hirsutus and Tinospora cardifolia as the larval forms survive on these weed hosts.
  • Smoking of the orchard during evening periods which repel the moths.
  • Bagging of fruits with paper bags or bags made of palmyra leaves.
  • Setting of light traps along with poison baiting (1L. Fruit juice + 20g sugar +2 ml malathion) so as to attract adults.
  • Avoid delayed harvesting to escape the pest attack as the pest attacks only the ripen fruits.
  • Foliar application of dichlorvos @ 1ml or carbaryl 2 g + NSKE 5% or neem oil 0.5% along with 0.5 ml of teepol or sandovit /L of water starting from 2 months before harvest at 15 days interval.

Aphids (Aphis spireacola, Toxoptera citricida & T.auranti)

The pest attacks the tender shoots, as a result of which the shoots get curled and growth checked. They also transmit citrus Tristeza virus which causes decline of citrus.

Control

Spray with thiamethoxam 0.3g or imidacloprid (confidor 200 SL) 0.5ml or dimethoate 2ml/L of water is recommended. Second spray to be at 10 days interval with either neem oil 0.5% or NSKE 5%.

Thrips (Scirtothrips citri)

The nymphs and adults lacerate the leaf tissue rind and cause ring like scarred area encircling the fruit stalk and irregular mottled patches on the rind. The tender foliage becomes spotted and pale in appearance. Adult citrus thrips are small, orange-yellow insects with fringed wings. A single generation may be completed in a period of 15 days and completes 8 to 10 generations per year.

Control

Spray imidacloprid 0.5 ml or dimethoate 2ml or spinosad 0.4ml or fipronil 2 ml/L, two times at 7 days interval during new flushing period is recommended.

Citrus Psylla (Diaphornia citri)

Adults and nymphs suck sap from new flush as a result of which the leaf curls and flowers drop. Greening (Huanglongbing) pathogen is transmitted by this insect. The adult holds its mottled brown body at a peculiar 30 degree angle to the leaf surface. Adults congregate on the leaf under surface; when disturbed, they jump and fly, hence the common name “jumping plant lice.”

Control

Spraying with novaluron 0.7ml or dimethoate 2ml per or thiamethoxam 0.3g or Lecanicilium lecani 1x109 @ 5g/L of water, two times at 15 days interval during new flushing period.

Snow scales (Unaspis aspidistrae)

Small white insets in large Number colonize on all plant parts like fruits, leaves, branches, trunk etc. and suck sap from them, thus devitalizing the tree.

Control

It is recommended that the tree trunk is rubbed off with pieces of gunny bags and then sprayed with methyl-O-demeton or triazophos 2ml or diafenthiouron 1g or acephate 1.5g/L of water completely covering the damaged parts.

Termites (Odentotermes obesus): Termitidae : Isoptera

The workers feed on seedlings and kill them. On grown up trees, the workers feed and roots, tunnel upwards into the main stem and may hollow it. When attack is from outside, they build mud galleries on tree trunks and feed beneath these galleries.

Control

Mud galleries on tree trunk should be scraped off and dusted with carbaryl or chlorpyriphos dust or drenched with chloriphyriphos solution @ 3-5 ml/liter of water around the tree basins.

Citrus Nematodes (Meloidogyne incognita, Tylenchulus semipenetrans)

Nematodes attack plant roots and suck sap from them. The attacked plant appears sickly, leaves drop off and braches dry up from tip towards down. This is called slow decline. Plant growth is stunted.

Control

  • During replanting of the nurseries neem cake or castor cake or pongamia cake should be applied @ 60-80 kg per one cent area.
  • Do not grow Solanaceous crops or bhendi, banana crops in citrus orchards.
  • Apply carbofuron granules@ 130-160g or thimmet @ 40-80g per plant basin. After 3 months, based on plant age apply 15-25 kg neem or castor or pongamia cake per plant for every 6 months.
  • Seedlings should be selected from nematode free nurseries

DISEASES

Gummosis or Root-rot (Phytophthora citrophthora, Phytophthora parasitica, Phytophthora palmivora)

The bark at the collar region peels off allowing gum exudation. Root system of infected free shows rotting of fibrous and main roots. Tree becomes weak, bear profuse flowering dies before fruit maturity.

Control

  • Selection of proper site with adequate drainage.
  • Graft union of the plant should be well above the soil (high budding: 30-46 cm or above).
  • Double ring method, with an inner ring at about 45cm and an outer ring around the tree, should be followed. It prevents the irrigation water from coming in direct contact with the trunk.
  • Scrape the gum portions of affected bark and apply Bordeaux paste/metalaxyl MZ paste or copper oxychloride paste on the affected portions. Apply paste to the tree trunks upto 2 feet height is recommended once a year.

Diplodia Gummosis(Diplodia natalensis)

The affected branches show oozing of gummy substance out of bark splitting.

Control

  • Remove the gum and apply Bordeaux paste.
  • Spray Carbendazim (1%) on twigs and branches twice at 15 days interval.
Dry Root rot (Fusarium solani) Infected roots become blackened and the bark portion of the roots easily peeled off from the root. Infected plant shows heavy flowering and fruiting and the plant dies before the fruits reach maturity stage. Remove all the fruits immediately noticing the initial symptoms of the dry root rot and follow the management practices as given below.

Control

  • For the diseased trees, apply 20ℓ of 1% Bordeaux mixture or 0.2% Carbendizim (2g/ℓ of water) at the tree basin immediately after the next day of irrigation.
  • Initial symptoms of root rot appear generally in summer season. Apply leaf mulches or agricultural wastes such as paddy husk, groundnut husk, dried leaves, black gram or green gram husk, saw dust to the infected trees at 2-3 inch thickness.
  • Immediately after the start of rains (August- September), apply green leaf manures such as neem, Crotalaria juncea, Cassia auriculata, Cissus quadrangularis, Vigna species below the soil in the tree basin. On top of the manure, apply single super phosphate (1kg/tree), mix thoroughly deep in to the soil. Green leaf manures helps in increasing the biocontrol agent populations such as Trichoderma in the soil and there by disease control.
  • Apply 10kg mixture of Trichoderma culture for each tree (mix 1kg Trichoderma culture + 90kg FYM + 10 kg neem cake, kept it aside for 10 days) at the trunk basins and mix it well. Repeat the same after 6 months. Application of 5kg of this mixture every year to the healthy trees prevents root rot.
  • Give micronutrient spray twice a year at the time of new flesh to make the nutritionally strong.

Ganoderma root rot (Ganoderma lucidum)

The entire plant wilts and dies in extreme cases. The roots become weak and pliable. Numerous brackets like objects are produced at the base of the stem and also in the trunk to some height.

Control

These mushrooms also infect Coconut, Mango, Jackfruit trees. So, collect and destroy the mushrooms on these crops. Continuously watch for the mushrooms, particularly in rainy season and destroy them. Cut the diseased older trunk portions and apply Bordeaux paste. Apply 1ℓ/Sq.m area of carbendazim (1gm/ℓ of water) or Aureofungin sal (1.5g/5ℓ of water) or Tridemorph (2.5g/ℓ of water).

Twig blight (Colletotrichum gloeosporioides, Botryodiplodia theobromae)

Light brown to dark brown discolouration of leaves. They get defoliated. The naked twigs have profused black coloured fructification on grayish twigs.

Control

Pruning and burning of the affected twigs before the rainy season followed by spraying of 0.1% Carbendazim (10gm in 10 lit of water) or Copper oxychloride 3g/ℓ of water twice at monthly interval reduces the disease.

Powdery mildew (Budida Tegulu) (Acrisporium tingitanium)

White powdery growth is formed on the surface of the leaves during December to February.

Control

Spraying of Karathane 0.1% or Wettable Sulphur 0.2% twice at 15 days interval reduces the disease incidence.

Felt disease (Septobasidium spp)

Soft felt like leathery fungal growth encircles petiole, leaf base, twigs, branches and fruit stacks. The causal fungus grows over the surface and it does not penetrate the bark tissues. It mainly seen on acidlime in costal districts of Andhra Pradesh.

Control

Pruning and destruction of diseased twigs before the onset of monsoon. Spraying of Monocrotophos (1.6mℓ) with Mancozeb (2g) or Captan (2g/ℓ of water) controls the scale insects and the disease.

Pink disease (Pellicularia salmonicolour)

Infected branches becomes yellowish and finally wilts. Whitish mycelial growth appears on the infected twigs. Later white or pink pustules appear on the twigs. When the bark is severely infected, it gets shredded, and the wood is exposed. Longitudinal cracking and gumming of the branches may also take place.

Control

Cut-off the diseased twigs, which are drying after rainy season and destroy them. Apply Bordeaux paste on the cut surface of the twigs.

Canker (Xanthomonas auxonopodis Pv. Citrii)

Corky out growths develop on the leaves, fruits and twigs. The disease is serious in acid lime.

Control

  • Canker tolerant acidlime variety ‘Balaji’ was developed by Citrus Research Station, Tirupati. The variety is canker, tolerant and high yielding. Farmers can obtain the variety from Citrus Research Station, Tirupati.
  • Diseased twigs and branches should be pruned and destroyed before the rainy season.
  • Spray Streptocycline (1g) + Copper oxychloride (30g) in 10ℓ of water, twice on young flushes in rainy season at 20 days interval.
  • Control of leaf miner in acidlime orchards can reduce canker.
  • To prevent canker on fruits, spray the above chemicals on small fruits twice at monthly interval. Spray should cover entire fruits.
  • If canker is present on trunk and main branches, scrap that portion and apply Bordeaux paste on the effected area.

Greening disease (Liberibactor asiaticum)

Close view of greening symptoms on leaves

Diseased sweet orange and acid lime fruits along with Healthy fruits;

Leaf patterns include chlorosis resembling zinc deficiency (sometimes dotted with green islands), and yellowing of veins. Reduction in fruit size and die-back of twigs are also noticed. The pathogen is spread by use of infected bud wood and by the citrus psylla (Diaphornia citri).

Control

  • Selection of certified disease free budlings.
  • Application of Dimethoate (2ml/lit) or Profinofos (2mℓ/ℓ) to control psylla (as in case of psylla control).

Viral Diseases

Tristeza disease (Quick decline or die-back)

Decay of roots, die-back of twigs, diminished fruit-set, vein-clearing in leaves and stem pittings are symptoms of tristeza virus. The disease is transmitted by budding and by certain aphids including (Toxoptera citricida, Aphis gossypi and A.craccivora).

Tristeza affected trees look chloratic and sickly in the early stages. Gradually the leaves drop and the defoliated twigs show die-back. The declining trees die gradually but sometimes apparently healthy trees die suddenly. Diseased trees usually blossom heavily. They bear small sized fruits. As the fruits develop, the tree wilts partly or completely. Vein clearing in young leaves of acidlime, which is seen intermittently when viewed against light is a characteristic symptoms.

In sweet orange the specific symptoms of tristiza is stem pitting on the root stocks such as Jambheri. It is fine pitting of inner face of bark in the portion of trunk below the bud union. The disease primarily spreads through the use of diseased bud wood by the nurserymen. Under field conditions, the disease is transmitted by the aphid, Taxoptera citricida.

Control

Tolerant rootstocks such as sweet orange, trifoliate orange, Cleopatra mandarin and Rangpurlime have to be used. Budded plants free from the virus are to be planted.

Mosaic disease

Symptoms appear on leaves and fruits. Affected leaves show irregular yellow or light green patches alternating with normal green areas. Reduction in leaf size and leaf drop is observed. Fruits show depressed yellow patches and elevated green areas. Reduction in fruit size is common. The disease is transmitted through infected bud wood.