Ppt on Major Diseases Of Brinjal: Causes Symptoms And Management Strategies

Introduction to Brinjal Diseases

Brinjal (Solanum melongena) is susceptible to several economically significant diseases.
Major diseases include damping off, Phomopsis blight, bacterial wilt, Fusarium wilt, Verticillium wilt, Alternaria blight, and little leaf.
These diseases can cause substantial yield losses and affect fruit quality.
Understanding disease etiology and epidemiology is crucial for effective management.

Causal organism: Phomopsis vexans (syn. Diaporthe vexans).
Symptoms include damping off in seedlings, leaf blight, and fruit rot.
Leaf blight: Brown, round to oval spots with grey centers and dark margins; spots may coalesce and dry.
Fruit rot: Pale sunken spots, black pycnidia on surface, mummification of fruit if infection is severe.

Pycnidia are globose to irregular, brown to black, present in affected tissues.
Conidiophores are hyaline, simple or branched; pycnidiospores are hyaline, one-celled, subcylindrical.
Stylospores are filiform, curved, hyaline, and septate.
Fungus survives in plant debris and is seed-borne; spreads via rain splash, implements, and insects.
Wet weather and high temperatures (30–32°C) favor disease development.

Practice sanitation: collect and destroy diseased debris, rotate crops, and use disease-free seeds.
Seed treatment with carbendazim (0.2%) or thiophanate methyl (0.2%) is recommended.
Spray carbendazim (0.1%), mancozeb (0.25%), or copper oxychloride (0.3%) at 10–14 day intervals upon disease initiation.

One of the most devastating diseases in solanaceous crops, especially in warm, humid regions.
Symptoms: Sudden wilting, drooping petioles, yellowing, stunting, and browning of vascular tissues.
Milky bacterial ooze from cut stems; excessive adventitious root formation may occur.

Causal agent: Ralstonia solanacearum, a gram-negative, motile, aerobic rod with polar flagella.
Five races and four biovars exist; in India, races 1 and 3, biovars II, III, and IV are prevalent.
Pathogen is soil- and seed-borne, survives in plant debris, tubers, wild hosts, and weeds for up to 2 years.
Infection occurs through wounds in roots; high soil moisture and temperature favor disease.

No effective chemical control; all commercial cultivars are generally susceptible.
Practice long crop rotation with non-solanaceous crops and avoid water movement from infected to healthy plants.
Green manuring or biofumigation with Brassica spp. can reduce soil inoculum.
Use bacterial antagonists (e.g., Pseudomonas fluorescens, Bacillus spp.) and soil solarization with dazomet.
Seedling dip in Streptocycline (100 ppm, 30 min) and use of resistant cultivars are partially effective.

Symptoms: Yellowing and wilting of lower leaves, stunted growth, V-shaped lesions from leaf margins.
Necrosis and browning of vascular tissues; lower leaves die and fall off, leading to plant death.
Longitudinal brown streaks visible under stem tissue, especially at the plant base.

Affects tomato, eggplant, potato, pepper, cabbage, cauliflower, cucumber, and pumpkin.
Management includes selecting resistant varieties, crop rotation, and discarding infected material.
Soil solarization, equipment sanitation, early-maturing varieties, weed control, and mulching with resistant tree material are recommended.

Symptoms: Yellowing of lower leaves at flowering, premature leaf death, and browning of vascular bundles.
One or more branches may be affected; cross-sections reveal vascular discoloration.

Mycelium is septate, hyaline, becoming cream-colored; some isolates produce blue or red pigment.
Microconidia are ellipsoidal, 1–2 celled; macroconidia are falcate, 3–5 septate, hyaline.
Chlamydospores are thick-walled, terminal or intercalary, solitary or in chains.
Pathogen is soil-borne, survives as mycelium and chlamydospores in debris and soil.
Spread via water, contaminated equipment, and infected transplants; favored by hot, dry weather and acidic soils (pH 5.6–6.5).

Practice crop rotation with non-solanaceous crops and use healthy seed.
Avoid water movement from infected to healthy plants.
Apply combined inorganic fertilizers and organic manures; phosphate and nitrate fertilizers reduce incidence.
Seed treatment with carbendazim (0.2%) and drenching with carbendazim/benomyl (0.1%) are effective.
Use Pseudomonas isolates from rhizosphere to reduce infection.

Caused by Alternaria solani and Alternaria alternata f.sp. lycopersici.
A. solani: Dark brown concentric ring spots (target board effect), coalescing into patches, leading to defoliation.
A. alternata: Small, angular, light brown spots on leaves, stems, and branches; no yellow halo.

A. solani: Septate, branched, light brown hyphae; beaked, muriform conidia with multiple septa.
A. alternata: Conidia are 1–5 septate, found on leaflet and stem lesions.
Pathogen survives in plant debris and is seed-borne; primary infection via conidia from soil debris.
Secondary spread by wind, water, and insects; optimal infection temperature is 25–30°C.

Remove and destroy infected plant debris; practice at least two years of crop rotation.
Use healthy seed and treat with captan (0.3%).
Remove lower foliage (15–20 cm) in indeterminate varieties to reduce humidity.
Spray chlorothalonil (0.2%) or mancozeb (0.25%) at 10–14 day intervals.