A) Bacterial Wilt of Brinjal

Causal Organism: Pseudomonas solanacearum (Now classified as Ralstonia solanacearum)

Symptoms:

• Wilting: Sudden wilting of the entire plant without yellowing of leaves. Affected plants may show temporary recovery at night but wilt again during the day.
• Stunting and Yellowing: Stunted growth followed by yellowing of foliage.
• Vascular Discoloration: Browning of the vascular tissues, visible when the stem is cut. A brown, sticky ooze may be observed when the stem is pressed.
• Bacterial Ooze: Milky-white, slimy bacterial ooze exudes from cut stems when dipped in water.
• Root Symptoms: Brown discoloration in the vascular bundles of roots.
• Fruit Symptoms: Infected plants may produce smaller and fewer fruits.

Pathogen Characteristics:

• Morphology: Non-spore forming, non-capsulated, and motile by a single polar flagellum.
• Biochemical Properties: Produces acid but no gas in dextrose, sucrose, lactose, and glycerol. Hydrolyzes starch with slight liquefaction of gelatin.

Mode of Spread and Survival:

• Primary Source: Infected plant debris and contaminated soil.
• Secondary Spread:
  • Through contaminated water, soil, farm tools, and machinery.
  • By infected seedlings or transplants.
  • Spread by rain splash, irrigation water, and soil movement.
• Survival:
  • Survives in the soil for over 16 months under favorable conditions.
  • Can persist in plant debris for up to 10 months.
  • Survives in alternate hosts such as tomato, potato, chili, and ginger.

Favorable Conditions:

• Temperature: Optimum range 25-35°C.
• Soil Moisture: High soil moisture and poor drainage promote disease.
• Soil Type: Sandy loam and clay loam soils with high organic matter favor disease spread.
• Nematode Infestation: Presence of root knot nematodes (Meloidogyne spp.) increases disease incidence.

Management Strategies

Cultural Practices:

• • Crop Rotation: Rotate with non-host crops like cereals (maize, sorghum) or crucifers (cabbage, cauliflower).
  • Sanitation: Remove and destroy infected plant debris.
  • Field Hygiene: Avoid working in wet fields to reduce the spread of the pathogen.
  • Raised Beds: Improve soil drainage to minimize waterlogging.
• Resistant Varieties: Use resistant varieties like Pusa Purple Long, Arka Nidhi, and Arka Keshav.
• Chemical Control: Copper Fungicides: Spray with 2% Bordeaux mixture or Copper oxychloride to reduce bacterial load.
• Soil Treatment: Soil solarization using transparent polythene sheets for 4-6 weeks during summer. Application of lime to reduce soil acidity and suppress pathogen activity.
• Nematode Management: Use nematicides or organic amendments to control root knot nematodes.
• Biological Control: Application of Pseudomonas fluorescens and Trichoderma harzianum as biocontrol agents.
• Quarantine Measures: Use disease-free seedlings and avoid planting in infected fields. Disinfect tools and equipment to prevent the spread of the pathogen.

Preventive Measures:

• Certified Seedlings: Use disease-free certified seeds or seedlings.
• Water Management: Avoid over-irrigation and use well-drained soils.
• Field Monitoring: Regularly inspect fields for early detection and removal of infected plants.
• Soil Amendments: Apply organic matter to improve soil health and suppress the pathogen

B) Damping Off of Brinjal

Causal Organisms: Pythium spp., Rhizoctonia solani, Fusarium spp., and Phytophthora spp.

Symptoms:

• Pre-Emergence Damping Off: Seeds rot before germination. Seedlings fail to emerge from the soil.
• Post-Emergence Damping Off: Sudden wilting and collapse of young seedlings. Water-soaked lesions at the base of the stem. Stem becomes thin and constricted at the soil line. Seedlings topple over and die.
• Root Rot: Decay and browning of roots. Poor root development and stunted growth.

Favorable Conditions:

• High soil moisture and poor drainage.
• High humidity and overcrowding of seedlings.
• Cool temperatures (18-25°C).
• Poor ventilation in nurseries or seedbeds.

Mode of Spread and Survival:

• Primary Source: Soil-borne pathogens in infected soil or plant debris.
• Secondary Spread: Through contaminated water, tools, and infected seeds. Movement by rain splash and irrigation.

Management Strategies:

• Cultural Practices:
  • Well-Drained Soil: Use raised beds to improve drainage.
  • Seed Treatment: Treat seeds with Carbendazim or Thiram before sowing.
  • Soil Solarization: Cover the soil with transparent polythene sheets for 4-6 weeks during summer.
  • Proper Spacing: Avoid overcrowding to enhance air circulation.
• Chemical Control: Drench soil with Copper oxychloride or Metalaxyl. Use Captan or Mancozeb as soil fungicides.
• Biological Control: Apply Trichoderma harzianum and Pseudomonas fluorescens as biocontrol agents.
• Sanitation: Remove and destroy infected seedlings and plant debris.
• Quarantine Measures: Use sterilized soil or potting mix in nurseries. Avoid using previously infected seedbeds.

C) Bacterial Wilt of Brinjal

Causal Organism: Pseudomonas solanacearum (Now classified as Ralstonia solanacearum)

Symptoms:

• Wilting: Sudden wilting without yellowing of leaves. Temporary recovery at night but wilting during the day.
• Vascular Discoloration: Browning of vascular tissues, visible when the stem is cut. Milky-white, slimy bacterial ooze from cut stems when dipped in water.
• Stunting and Yellowing: Stunted growth and yellowing of leaves.
• Fruit Symptoms: Smaller and fewer fruits on infected plants.

Pathogen Characteristics:

• Morphology: Non-spore forming, non-capsulated, and motile by a single polar flagellum.
• Biochemical Properties: Produces acid but no gas in dextrose, sucrose, lactose, and glycerol. Hydrolyzes starch with slight liquefaction of gelatin.

Mode of Spread and Survival:

• Primary Source: Infected plant debris and contaminated soil.
• Secondary Spread: Through contaminated water, soil, farm tools, and machinery. Infected seedlings or transplants. Spread by rain splash, irrigation water, and soil movement.
• Survival: Survives in the soil for over 16 months under favorable conditions. Can persist in plant debris for up to 10 months. Survives in alternate hosts like tomato, potato, chili, and ginger.

Favorable Conditions:

• Temperature: Optimum range 25-35°C.
• Soil Moisture: High soil moisture and poor drainage.
• Soil Type: Sandy loam and clay loam soils with high organic matter.
• Nematode Infestation: Presence of root knot nematodes (Meloidogyne spp.) increases disease incidence.

Management Strategies:

• Cultural Practices:
  • Crop Rotation: Rotate with non-host crops like cereals (maize, sorghum) or crucifers (cabbage, cauliflower).
  • Sanitation: Remove and destroy infected plant debris.
  • Field Hygiene: Avoid working in wet fields to reduce the spread of the pathogen.
  • Raised Beds: Improve soil drainage to minimize waterlogging.
• Resistant Varieties: Use resistant varieties like Pusa Purple Long, Arka Nidhi, and Arka Keshav. Chemical Control: Copper Fungicides: Spray with 2% Bordeaux mixture or Copper oxychloride.
• Soil Treatment: Soil solarization using transparent polythene sheets for 4-6 weeks during summer. Application of lime to reduce soil acidity and suppress pathogen activity.
• Nematode Management: Use nematicides or organic amendments to control root knot nematodes.
• Biological Control: Application of Pseudomonas fluorescens and Trichoderma harzianum as biocontrol agents.
• Quarantine Measures: Use disease-free seedlings and avoid planting in infected fields. Disinfect tools and equipment to prevent the spread of the pathogen.

Preventive Measures:

• Certified Seedlings: Use disease-free certified seeds or seedlings.
• Water Management: Avoid over-irrigation and use well-drained soils.
• Field Monitoring: Regularly inspect fields for early detection and removal of infected plants.
• Soil Amendments: Apply organic matter to improve soil health and suppress the pathogen

D) Phomopsis Blight and Fruit Rot of Brinjal

Causal Organism: Phomopsis vexans

Symptoms:

1. Leaf Blight:
   • Circular to irregular brown spots with gray centers on leaves.
   • Lesions may coalesce, causing blighting and premature leaf drop.
   • Severe infection leads to complete defoliation.
2. Stem Lesions: Sunken brown lesions on stems and petioles. Lesions may girdle the stem, causing wilting and plant death.
3. Fruit Rot:
   • Small, sunken, circular spots on young fruits.
   • Spots enlarge, turn dark brown, and become sunken with concentric rings.
   • Infected fruits become soft, shriveled, and unmarketable.
   • White to gray fungal growth with black pycnidia (fruiting bodies) on rotting fruits.

Pathogen Characteristics:

• Fungus Type: Phomopsis vexans is an ascomycetous fungus producing both sexual and asexual spores.
• Pycnidia: Black, flask-shaped fruiting bodies formed on infected plant parts.
• Spores: Two types of spores:
  • • Alpha Conidia: Hyaline, one-celled, oval, and non-septate.
    • Beta Conidia: Filiform, curved, and thin-walled.

Mode of Spread and Survival:

• Primary Source: Infected seeds and plant debris.
• Secondary Spread: Airborne conidia dispersed by wind and rain splashes. Infected transplants, contaminated soil, and farm tools.
• Survival: Survives in crop debris, seeds, and soil for several years. Pycnidia on plant debris act as the primary source of inoculum.

Favorable Conditions:

• Temperature: Optimum range 25-30°C.
• Humidity: High humidity (>85%) and frequent rainfall favor disease development.
• Water Splashing: Rain splash or overhead irrigation spreads conidia.
• Dense Planting: Poor air circulation promotes infection.

Management Strategies:

• Cultural Practices:
  • Crop Rotation: Rotate with non-host crops (cereals, pulses) for at least 2-3 years.
  • Sanitation: Remove and destroy infected plant debris and crop residues.
  • Proper Spacing: Maintain adequate spacing for good air circulation.
  • Staking: Use staking to avoid contact between fruits and soil.
  • Irrigation Management: Avoid overhead irrigation to minimize leaf wetness.
  • Field Hygiene: Disinfect tools and equipment to prevent pathogen spread.
• Resistant Varieties: Grow resistant or tolerant varieties like Pusa Purple Long and Arka Nidhi.
• Chemical Control:
  • Seed Treatment: Treat seeds with Captan (3 g/kg) or Thiram (3 g/kg) before sowing.
  • Fungicide Sprays: Spray with Mancozeb (0.25%), Chlorothalonil (0.2%), or Carbendazim (0.1%) at 10-15 days intervals. Use Copper oxychloride (0.3%) or Thiophanate-methyl (0.1%) for effective control.
• Biological Control: Application of Trichoderma viride and Pseudomonas fluorescens as biocontrol agents.
• Quarantine Measures: Use disease-free seeds or seedlings from reliable sources. Avoid planting brinjal in previously infected fields.

Preventive Measures:

• Certified Seeds: Use certified disease-free seeds for sowing.
• Field Monitoring: Regularly inspect fields and remove infected plants.
• Soil Solarization: Cover the soil with transparent polythene sheets for 4-6 weeks to kill pathogens.
• Seedling Treatment: Drench nurseries with Copper oxychloride or Mancozeb solution.

E) Sclerotinia Blight of Brinjal

Causal Organism: Sclerotinia sclerotiorum

Symptoms:

1. Initial Symptoms: Water-soaked lesions on stems, leaves, and fruits. Lesions expand, turning light brown and causing wilting.
2. Cottony Growth: White, cottony fungal mycelium develops on infected parts under high humidity.
3. Sclerotia Formation: Hard, black, irregular-shaped sclerotia form on or inside the infected tissue. Sclerotia resemble mustard seeds and help the fungus survive in soil.
4. Fruit Rot: Infected fruits become soft, watery, and rotten. Fruit surface may show white mycelial growth with sclerotia.

Mode of Spread and Survival:

• Primary Source: Soil-borne sclerotia act as the primary inoculum.
• Secondary Spread: Airborne ascospores, rain splash, and contaminated tools.
• Survival: Sclerotia can survive in the soil for 5-8 years.

Favorable Conditions:

• Temperature: 20-25°C is optimal for disease development.
• Humidity: High humidity (>85%) promotes fungal growth.
• Dense Canopy: Poor ventilation and dense foliage increase disease severity.

Management Strategies:

1. Cultural Practices:
   • Crop Rotation: Avoid planting brinjal after susceptible crops like tomato, beans, and cabbage.
   • Field Sanitation: Remove and burn infected plant debris.
   • Proper Spacing: Maintain adequate spacing to reduce humidity.
   • Deep Plowing: Bury sclerotia deep in the soil to prevent germination.
2. Chemical Control: Soil Treatment: Apply PCNB (Quintozene) before planting. Fungicide Sprays: Use Carbendazim (0.1%), Thiophanate-methyl (0.1%), or Iprodione (0.2%) at 10-15 days intervals.
3. Biological Control: Trichoderma harzianum and Coniothyrium minitans are effective against sclerotia.

F) Little Leaf of Brinjal

Causal Organism: Phytoplasma (transmitted by the leafhopper Hishimonus phycitis)

Symptoms:

1. Leaf Symptoms: Leaves become small, pale green, and narrow. Leaf blades are reduced to tiny scales or outgrowths. Internodes shorten, giving a bushy appearance.
2. Flower and Fruit Symptoms: Flower buds become deformed and do not open. Flowers are transformed into leafy structures (phyllody). Fruits are either not formed or are small, hard, and seedless.
3. Stunted Growth: Plants exhibit stunted growth with excessive branching. In severe cases, the entire plant appears bushy and dwarfed.

Mode of Spread and Survival:

• Primary Source: Infected plant material acts as the primary inoculum.
• Vector Transmission: Transmitted by leafhoppers, mainly Hishimonus phycitis.
• Survival: Phytoplasma survives in perennial weed hosts and vectors.

Favorable Conditions:

• Temperature: Warm temperatures favor vector multiplication.
• Host Availability: Presence of perennial weed hosts increases disease incidence.

Management Strategies:

1. Cultural Practices:
   • Rogueing: Remove and destroy infected plants immediately.
   • Weed Control: Eradicate weed hosts like Xanthium strumarium and Parthenium hysterophorus.
   • Crop Rotation: Rotate with non-susceptible crops like cereals.
2. Vector Control: Spray Imidacloprid (0.03%) or Dimethoate (0.05%) to control leafhoppers. Use yellow sticky traps to monitor and control vector populations.
3. Resistant Varieties: Use resistant varieties, if available, to reduce disease impact.

Preventive Measures:

• Certified Seeds: Always use disease-free seeds or seedlings.
• Field Hygiene: Avoid planting brinjal in previously infected fields.
• Monitoring: Regular inspection for early detection and removal of infected plants.