Tag: physiological disorders

• Citrus crops are prone to various nutrient deficiencies, physiological disorders, pests, and diseases.
• Proper identification and management are crucial for healthy growth and high yield.
• Integrated management practices combine cultural, chemical, and biological methods.

• Sudden temperature changes and moisture stress.
• Cracking may be radial or transverse.
• Secondary infection by Aspergillus, Fusarium, or Alternaria possible.

Management:

• Apply light irrigation at frequent intervals.
• Apply potassium during fruit development.

• Juice vesicles become hard, enlarged, and opaque grayish.
• Pulp density increases; juice has more minerals, less carbohydrate and organic acid.
• Lignification of juice cells forms sclerenchyma.

Causes:

• High humidity, temperature fluctuations, excess nitrogen, large fruit size, susceptible rootstocks.
• Young trees and mandarins on Jatti Khatti rootstock are more prone.

Management:

• Avoid excess moisture.
• Spray lime (20 kg in 450 L water).
• Spray zinc (0.5%) and copper (0.5%).

• Exposed fruit develops yellow patches, turning brown and hard.
• Inner portion becomes desiccated and discoloured.
• Fruits malformed, low juice content, may drop; leaves turn brown.

Management:

• Spray lime solution (20 g/L) before summer.
• Regulate irrigation to reduce temperature.
• Mulch tree basins.

• Stunted growth, leaf mottling, yellowing, and shedding.
• Excess flowering, poor fruit set, sun blotching of fruits.

Causes:

• Calcium carbonate or clay in soil, rootstock-scion incompatibility, salinity, waterlogging, poor orchard management.

Management:

• Ensure proper drainage and orchard management.
• Use resistant rootstocks and disease-free budwood.

• Spray dimethoate 2 ml/L + neem oil 3%.

Leaf Caterpillar:

• Apply endosulfan 2 ml/L for moderate to severe infestation.

Sucking Pests (Whitefly):

• Spray quinalphos 2 ml/L.

Nematodes:

• Apply carbofuran 75 g/tree or Pseudomonas fluorescens 20 g/tree.

• Prune dried twigs and spray 0.3% copper oxychloride.

Scab:

• Spray 1% Bordeaux mixture.

Tristeza Virus:

• Remove and destroy infected trees.
• Spray monocrotophos 1 ml/L to control aphid vectors.
• Use pre-immunized seedlings for planting.

• Acid lime starts bearing from the 3rd year after planting.
• Main crop harvested at different times across regions; average yield is 20–25 kg/tree/year.
• Treat fruits with 4% wax emulsion and pre-pack in 200-gauge polythene bags (1% ventilation) to extend shelf life over 10 days.
• Store limes at 18°C for best results.
• Low-cost storage tanks with double-layer brickwork and wet sand interspace can be used for storage.

• Combine cultural, chemical, and biological methods for sustainable citrus production.
• Regular monitoring and early detection of disorders, pests, and diseases.
• Use resistant varieties and healthy planting material.
• Maintain balanced nutrition and proper irrigation.
• Adopt proper pruning, sanitation, and post-harvest handling.

• Banana is a major tropical fruit crop with significant economic importance.
• Production is limited by physiological disorders, pests, and diseases.
• Effective management is essential for sustainable yield and fruit quality.

• Observed in cv. Poovan, mainly in Tamil Nadu.
• Fruits are conical, ill-filled, with a prominent central core and non-viable seeds.
• Spray 2,4-D at 20 ppm when last hand opens to prevent disorder.

Hard Lump

• Occurs in cv. Rasthali; pulp is pinkish-brown, firm, and tastes unripe.
• Spray 2,4-D at 1000 ppm or dip peduncle cut end for 5 minutes to reduce lumps.

Sunscald

• Caused by direct sun exposure on bunches and peduncle.
• Cover bunches and peduncle with banana or flag leaves to prevent damage.

• Short, narrow leaves clustered at pseudostem apex (‘bunchy’ appearance).
• Leaf margins wavy and rolled upward in advanced stages.

Management:

• Remove affected plants with rhizome.
• Plant virus-free suckers.
• Control aphids with insecticides (e.g., 0.3% Rogor, 0.05% Monocrotophos).

Banana Bract Mosaic Virus
Pathogen: Banana bract mosaic virus, transmitted by Aphis gossypii and Pentalonia nigronervosa.
Symptoms:

• Discoloration and necrotic streaks on male bud bracts.
• Spindle-shaped discoloration on pseudostem.

Management:

• Early detection and removal of infected plants.
• Control vectors as for other viral diseases.

Banana Streak Virus
Pathogen: Banana streak virus, transmitted by citrus mealybug (Planococcus citri).
Symptoms:

• Foliar mosaic and necrotic streaks on leaves.

• Yellowing and withering of leaves; petiole breaks and hangs.
• Longitudinal splitting of pseudostem; plant death.

Management:

• Remove infected plants; apply lime (2 kg/pit) and fallow for 6 months.
• Grow resistant varieties (Dwarf Cavendish, Poovan, Nendran).
• Crop rotation with paddy in wetland areas.
• Apply carbendazim (50–60 mg) in corm at 45° angle.

Sigatoka Leaf Spot
Pathogen: Mycosphaerella musicola.
Symptoms:

• Yellowish-green streaks along veins, enlarging into elongated spots.
• Coalescence of spots leads to leaf drying.

Management:

• Spray copper oxychloride or carbendazim (500 g/ha).
• Avoid close planting to reduce humidity.

• Yellowing starts from inner leaves, spreads upward; wilting of all leaves.

Management:

• Ensure good drainage.
• Biological control with Pseudomonas fluorescens.
• Crop rotation with non-hosts (e.g., sorghum).

Tip Over (Heart Rot)
Pathogen: Erwinia carotovora.
Symptoms:

• Rotting of central tender leaf; pseudostem detaches easily from corm.
• Bacterial ooze from corm and pseudostem edges.

Management:

• Use disease-free suckers.
• Grow resistant varieties (e.g., Poovan).

• Adopt integrated pest and disease management (IPDM) for sustainable production.
• Use resistant varieties and healthy planting material.
• Practice crop rotation and proper field sanitation.
• Apply recommended fungicides and insecticides judiciously.
• Bunches mature 100–150 days after flowering.
• Average yields (t/ha/year): Poovan 40–50, Monthan 30–40, Robusta 50–60, Dwarf Cavendish 50–60.

• Mango faces several physiological disorders, pests, and diseases affecting yield and quality.
• Major problems include alternate bearing, malformation, spongy tissue, and fruit drop.
• Effective integrated management is essential for sustainable production.

• Irregular fruiting pattern with heavy crop one year and little or none the next.

Occurrence:

• Common in north Indian varieties; south Indian varieties are mostly regular bearers.

Management:

• Soil drenching with paclobutrazol (5–10 g/tree) induces flowering and increases yield.
• Proper nutrition and irrigation management help reduce alternate bearing.

• Vegetative malformation (common in seedlings and young plants).
• Floral malformation (affects bearing trees, reduces productivity).

Symptoms:

• Bunchy top: compact leaves at shoot apex; arrested shoot growth.
• Malformed panicles in floral malformation.

Management:

• Deblossoming and spraying 200 ppm NAA reduce malformed panicles.
• Remove and destroy affected shoots and panicles.

• Distal end of fruit turns black, hardens, and ripens prematurely.
• Affected fruits become unmarketable.

Causes:

• Smoke from brick-kilns (CO, CO2, SO2, acetylene) within 600 m.

Management:

• Increase chimney height of brick-kilns.
• Spray borax (0.6%) at 10–14 day intervals from fruit set.

• Cluster of small, dark green fruitlets at panicle tip (bunch tip).
• Fruitlets grow to marble size, then growth ceases.

Causes:

• Adverse climate, especially low temperature during February–March.
• Poor embryo development.

Management:

• Protect trees from adverse weather; select tolerant varieties.

• Specific to Alphonso mango; affects export quality.

Symptoms:

• Normal external appearance; internal flesh patch is spongy, yellowish, and sour.

Causes:

• High temperature, convective heat, post-harvest sun exposure.

Management:

• Use sod culture and mulching to reduce incidence.
• Harvest at three-fourths maturity.
• Use resistant hybrids (e.g., Ratna, Arka Puneet).

• High fruit drop rate, especially in first four weeks after fruit set (up to 99%).

Management:

• Regular irrigation during fruit development.
• Timely pest and disease control.
• Apply NAA (50 ppm) or 2,4-D (20 ppm) six weeks after fruit set.

• Spray phosalone 0.05%, carbaryl 2 g/L, or phosphamidon 1 mL/L.

Nut Weevil (Cryptorrhynchus mangiferae):

• Maintain orchard cleanliness; destroy adults in bark crevices.
• Spray fenthion 0.1%.

Stem Borer (Batocera rufomaculata):

• Apply monocrotophos 36 WSC (10 mL/tree) via padding.
• Apply carbofuran 3G (5 g/bore hole) and plug with mud.

Fruit Fly (Bactrocera spp.):

• Plough interspaces to expose pupae.
• Use methyl eugenol traps; remove and bury fallen fruits.

• Apply sulphur dust (350 mesh) in early morning.
• Spray wettable sulphur 0.2% or tridemorph 0.05%.

Anthracnose and Stalk/End Rot (Colletotrichum gloeosporioides):

• Spray mancozeb 0.2% or carbendazim 0.1% preharvest, 3 times at 15-day intervals.

Sooty Mould (Capnodium spp.):

• Spray dimecron 0.03% + maida 5% (1 kg maida/starch boiled in 1 L water, diluted to 20 L).

• Adopt integrated pest and disease management (IPDM) for sustainable mango production.
• Combine cultural, chemical, and biological methods for effective control.
• Regular monitoring and timely interventions are crucial.
• Use resistant varieties and proper orchard sanitation.