Tag: Vegetable Crops

• Okra (Abelmoschus esculentus) is affected by several fungal and viral diseases.
• Major diseases: Powdery mildew, Fusarium wilt, Alternaria leaf spot, Yellow vein mosaic.
• Effective management requires knowledge of pathogens, symptoms, and control measures.

• White or grayish powdery growth on upper leaf surfaces, later covering entire leaf.
• Lower leaf surfaces may also be infected.
• Affected leaves dry and fall prematurely, reducing yield.

Disease Cycle:

• Overwinters as dormant mycelium or cleistothecia on infected leaves.
• Secondary spread by wind-borne conidia.
• Favored by 60–80% relative humidity and dry conditions.

Management:

• Spray fungicides: wettable sulphur (0.25%), dinocap (0.1%), carbendazim (0.1%), hexaconazole (0.05%), or difenoconazole (0.05%).
• Repeat sprays at 10–14 day intervals.
• Biocontrol: Ampelomyces quisqualis, Trichoderma spp., Bacillus subtilis.
• Use azadirachtin (0.03% EC) as needed.

• Yellowing, stunting, wilting, and rolling of leaves.
• Dark brown vascular discoloration in stems.
• Severe cases: stem blackening and plant death.

Etiology:

• Produces hyaline mycelium, microconidia (single/two-celled), macroconidia (3–4 septa), and chlamydospores.

Disease Cycle:

• Survives as chlamydospores in soil and infected seeds.
• Optimum temperature for growth: 25°C; disease develops at 22–28°C.

Management:

• Use healthy, treated seed (carbendazim 0.2%).
• Practice crop rotation and soil solarization.
• Remove and destroy affected plants.
• Grow resistant varieties: CS-3232, CS-8899, IS-6653, IS-7194, Pusa Makhameli, Pusa Sawani.

• Brown leaf spots with pale margins and yellow halos.
• Lesions enlarge, show concentric rings, and coalesce.
• Severe infection causes leaf drying and defoliation.

Etiology:

• Produces cylindrical conidiophores and brown, muriform conidia with transverse and longitudinal septa.

Disease Cycle:

• Survives in infected plant debris, weed hosts, and seeds.
• Secondary spread by wind-borne conidia.

Management:

• Remove and destroy infected debris and weeds.
• Seed treatment with Thiram (6 g/kg).
• Spray Mancozeb (0.2%) after disease appearance.

• Vein yellowing and thickening, forming a network pattern.
• Leaves become chlorotic and yellow under severe infection.
• Plants are stunted with small, pale fruits.

Disease Cycle:

• Transmitted by whitefly (Bemisia tabaci) in a persistent manner.
• Wild and cultivated plants act as inoculum sources.
• Favored by dry, hot weather with low rainfall.

Management:

• Destroy wild hosts and avoid mixed cropping with pumpkin.
• Adjust sowing dates to avoid peak whitefly populations.
• Remove infected plants up to 55 days after sowing.
• Grow resistant cultivars: Punjab Padmini, Punjab-8, Prabhani Kranti, Hissar Unnat.
• Spray systemic insecticides (cypermethrin, deltamethrin, triazophos) to control vectors.

• Use disease-free, treated seeds and resistant varieties.
• Practice crop rotation, field sanitation, and timely removal of infected plants.
• Apply recommended fungicides and insecticides judiciously.
• Adopt biological control agents where feasible.
• Monitor fields regularly for early detection and management.

• Cabbage is susceptible to several economically important fungal diseases.
• Fungal pathogens affect yield and quality.
• Early identification and management are crucial for disease control.
• Integrated approaches are recommended for sustainable management.

• Pathogen: Rhizoctonia solani.
• Symptoms: Stem constriction at base, stunted growth, seedlings may break at ground level.
• Favored by mechanical injury and wet conditions.
• Management: Use certified disease-free transplants, avoid injury, ensure good drainage.

• Pathogen: Fusarium oxysporum f. sp. conglutinans.
• Symptoms: Leaf yellowing, wilting, stunted growth, twisted stems, unilateral midrib curvature.
• Soil-borne and persists for years.
• Management: Grow resistant varieties, crop rotation, use disease-free seed.

• Pathogen: Leptosphaeria maculans (Phoma lingam).
• Symptoms: Light brown stem lesions with purplish margins, black dots (pycnidia), cankering at base.
• Seed and residue-borne.
• Management: Use disease-free seed, hot water seed treatment, crop rotation, sanitation.

• Pathogen: Alternaria brassicae, A. brassicicola.
• Symptoms: Circular brown to black spots with concentric rings and yellow halos.
• Seedborne and airborne spread.
• Management: Remove crop debris, seed treatment, crop rotation, fungicide application.

• Pathogen: Plasmodiophora brassicae (plasmodiophoromycete, not true fungus).
• Symptoms: Root galls, wilting, stunted and yellow leaves, premature bolting.
• Favored by acidic, moist soils.
• Management: Use clean seedbeds, long crop rotations, lime soil to raise pH, resistant varieties.

• Pathogens: Fusarium spp., Pythium spp., Rhizoctonia solani.
• Symptoms: Seedling collapse, wet rot at stem base, missing or wilted seedlings.
• Favored by high moisture and poor drainage.
• Management: Use sterilized soil, raised beds, good drainage, biocontrol agents.

• Pathogen: Hyaloperonospora brassicae (formerly Peronospora parasitica).
• Symptoms: Yellow patches on upper leaf surface, white fluffy growth below, leaf drop, black spots on curds.
• Favored by cool, moist conditions.
• Management: Resistant varieties, crop rotation, debris removal, avoid leaf wetting, fungicides.

• Pathogen: Erysiphe cruciferarum.
• Symptoms: White powdery growth on upper leaf surfaces, reduced vigor.
• Favored by dry, warm conditions.
• Management: Resistant varieties, fungicides, avoid excess nitrogen, reduce drought stress.

• Pathogen: Albugo candida (oomycete, not true fungus).
• Symptoms: White blisters on leaf undersides, yellow patches above, stem distortion, leaf galls.
• Favored by cool, moist weather.
• Management: Resistant varieties, crop rotation, fungicides.

• Pathogen: Mycosphaerella brassicicola.
• Symptoms: Grey leaf lesions with black dots in concentric rings, reduced growth, delayed harvest.
• Spread by seed and debris.
• Management: Hot water seed treatment, fungicides, remove infected plants and debris.

• Pathogens: Sclerotinia sclerotiorum, S. minor.
• Symptoms: Water-soaked lesions, fluffy white mycelium, black sclerotia inside stems.
• Favored by high humidity and dense canopy.
• Management: Improve air circulation, avoid injury, crop rotation, remove infected debris.

• Pathogen: Rhizoctonia solani.
• Symptoms: Tan or brown lesions on outer leaves, rapid head rot.
• Favored by wet, poorly drained soils.
• Management: Raised beds, proper fertilization, maintain plant health.

• Pathogen: Phytophthora megasperma.
• Symptoms: Leaf margin discoloration (red/purple), root and stem rot, plant wilting and death.
• Favored by poorly drained soils.
• Management: Improve drainage, crop rotation, soil treatments, fungicides.

• Use disease-free seed and resistant varieties.
• Practice crop rotation and field sanitation.
• Maintain proper drainage and avoid plant injury.
• Apply fungicides judiciously as needed.
• Monitor regularly for early detection and control.

• Brinjal (Solanum melongena) is affected by several major diseases.
• Diseases reduce yield and fruit quality significantly.
• Understanding pathogens and symptoms is crucial for effective management.

• Pathogen: Phytoplasma, localized in phloem sieve tubes.
• Symptoms: Small, yellow, soft leaves; shortened petioles and internodes; bushy appearance.
• Flowers, if formed, remain green; fruiting is rare and fruits are hard, necrotic, and mummified.
• Spread by leafhoppers (mainly Hishimonas phycitis); survives in weed hosts.

• Grow tolerant varieties: Pusa Purple Round, Pusa Purple Cluster, Arka Sheel.
• Destroy affected plants and eradicate solanaceous weeds.
• Spray methyl demeton (2 ml/L) or apply phorate granules to soil.
• Seed dip in tetracycline (10–50 ppm) to reduce infection.

• Pathogen: Ralstonia solanacearum, a Gram-negative, motile rod.
• Symptoms: Sudden wilting, leaf epinasty, yellowing, stunting, vascular browning, bacterial ooze from cut stems.
• Soil and seed borne; survives in plant debris, wild hosts, and weeds.
• Spread via irrigation water, infested soil, and contaminated tools.

• Favoured by high soil moisture and temperature.
• Resistant varieties: Pant Samrat, Arka Nidhi, Arka Neelakantha, Surya, BB 1, 44, 49.
• Crop rotation with non-solanaceous crops; green manuring with Brassica spp.
• Soil solarization (125 μm polyethylene, 8–10 weeks); biological control with Pseudomonas fluorescens, Bacillus spp.
• Seed and soil treatment with antagonistic P. fluorescens; seedling dip before transplanting.

• Pathogen: Phomopsis vexans (asexual stage), Diaporthe vexans (sexual stage).
• Attacks all growth stages; most destructive on fruits.
• Symptoms: Damping-off in nursery, collar rot, leaf spots with pycnidia, stem cankers, sunken fruit spots, soft rot, mummified fruits.
• Pathogen is seed-borne and survives in plant debris as mycelium and pycnidia.

• Disseminated by rain splash, irrigation water, tools, and insects.
• Favoured by high humidity, temperatures around 26°C, and wet weather.
• Management: Remove crop debris, crop rotation, use disease-free seed.
• Hot water seed treatment (50°C, 30 min); seed treatment with thiophanate methyl (1 g/kg).
• Spray thiophanate methyl or carbendazim (0.1%) at 20-day intervals.

• Pathogen: Cercospora melongenae and related species.
• Symptoms: Large, brown to grayish-brown circular or irregular leaf spots; coalescence leads to premature leaf drop and fruit rot.
• Fungus survives in soil debris and infected seeds.
• Favoured by high humidity, warm days, cool nights, and persistent dew.

• Destroy crop debris; practice crop rotation and use disease-free seeds.
• Maintain wider plant spacing to reduce humidity.
• Spray zineb (0.25%), carbendazim (0.1%), or thiophanate methyl (0.1%) at 10–14 day intervals after disease onset.

• Use resistant/tolerant varieties and certified disease-free seeds.
• Practice crop rotation, field sanitation, and weed management.
• Apply chemical and biological controls judiciously.
• Monitor environmental conditions and implement timely interventions.