Phytophthora blight
A water mould that causes sudden wilting, dark stem lesions and white-fuzzed rotting fruit in peppers and cucurbits during warm, wet weather.
Also known as: Phytophthora crown and fruit rot, Phytophthora wilt
Symptoms and identification
Dark, water-soaked lesions appear on stems at or above the soil line, and leaves wilt suddenly while still green. Fruit develop soft, dull, sunken patches covered with a white, powdery growth. Plants may die within days in hot, wet weather.
Causes
The pathogen survives in soil and spreads in water and by splashing rain. Heavy, poorly drained soils, flooded beds and overhead irrigation allow it to spread through a planting quickly.
Organic treatment
Remove and destroy infected plants and fruit and do not compost them. Improve drainage, and switch to drip irrigation.
Prevention
Plant in raised beds with good drainage, mulch to stop splashing, avoid wet feet, rotate crops for at least three years and clean tools. Pick fruit before it sits on wet soil.
Chemical treatment (use with care)
Fungicides labelled for Phytophthora can help protect healthy plants if used early and rotated, as the label directs.