Late Blight
Phytophthora infestans
How to Identify
Peak season: Cool, humid conditions (Dec-Feb North India)
3-Tier Organic Treatment Ladder
Always start with Tier 1. Move to higher tiers only if lower tiers fail. This approach preserves beneficial insects and keeps costs low.
Tier 1: Preventive
Yellow sticky traps
When: Hang at crop height, 1 per 5 m²
Ladybird beetles protection
When: Never spray when ladybirds present — they eat 400 aphids/day
Use resistant varieties
When: At variety selection
Raised bed planting with good drainage
When: At field preparation
Yellow sticky traps
When: Preventive
Protect ladybird beetle populations
When: Avoid broad-spectrum sprays unnecessarily
Yellow sticky traps
When: During new flush emergence
Yellow traps for adult moths
When: From transplanting
Companion plant dill/mustard trap border
When: At planting
Yellow/light traps
When: 1 UV light trap per 2 acres from 40 DAS
Drain field water temporarily
When: Removes breeding habitat
Yellow sticky traps
When: 1 per 5m², from establishment
Intercrop with marigold
When: At planting — whitefly decoy
Pheromone traps
When: Install at sowing, monitor moth activity
Trichoderma soil application
When: Preventive at planting
Tier 2: Early Treatment
Neem seed kernel extract 5%
When: Spray when population exceeds 10/leaf
Soap solution 2%
When: Insecticidal soap spray on colonies
Bacillus subtilis soil drench
When: Preventive at planting
Neem oil 2% spray
When: Weekly when population exceeds threshold
Neem oil spray
When: At new flush stage
Bt spray (most effective tool)
When: Every 5-7 days during pressure
Neemastra 5% spray
When: At base of plants when damage first seen
Beauveria bassiana 5 mL/L
When: Spray at base of plants in evening
Beauveria bassiana spray
When: Weekly during infestation
NPV spray (Spodoptera-specific)
When: At first larval signs
Bt spray
Product: 2 mL/L
When: Target whorl directly
Bordeaux mixture 1% spray
When: Every 10-14 days during humid period
Tier 3: Emergency Intervention
Tobacco decoction 2%
When: Severe infestation, spray in evening
Tobacco decoction spray
When: Severe infestation
Beauveria bassiana
When: Severe infestation
Neemastra 5% spray
When: Severe infestation
Neem-based + sand in whorl
When: Physical barrier combined with spray
Copper oxychloride spray
When: Severe outbreak