Choeanephora blight/ wet rot

Initial symptoms are characterized by a darkening and wilting of flowers, flower buds or growing points (blossom blight). The disease then spreads downward, producing water-soaked lesions on leaves, giving them a silvery tinge. Older lesions turn necrotic and appear dried out, resulting in blighted leaf tips and margins. On stems, signs of rot are visible in the form of brown to black patches and die-back. Eventually, the whole plant may wilt. Black soft rot can also develop on young fruits, usually at the blossom end. A close inspection will reveal silvery, hair-like growth on all infected tissues. In seedlings, symptoms may be confused with Phytophthora blight.

Causal organism : Coeanephora cucurbitarum (Berk. & Ravenel) Thaxt

Damage symptoms:

• Plants from seedling to early flowering stage are susceptible


• Being a weak parasite the fungus colonises dead or dying tissues before it actively


• invades living tissues


• Fruit infection is observed predominantly around calyx


• The pathogen attacks flowers through the senescing petals and overgrows on flowers resulting in brown or black mass of rotten tissue


• Flower stalks, buds and leaves will be attacked subsequently


• On infected tissues stiff silvery mass of whisker-like or hairy strands of the fungal growth develops on which black mass of spores is produced which is the chief diagnostic feature


• Infected young fruits may abort


• Individual branches of plants may be attacked which show dieback


• Stems of infected plants appear wet and green and the bark peels of in to shreds

Survival and spread:

• Primary: Zygospores on seeds and diseased crop debris in soil.


• Secondary: Conidia (sporangiospores) dispersed by rain splash and wind.

Favourable conditions:

• Warm, Rainy and wet weather Temp, 28°C with RH more than 97%


• Extended periods of high rainfall followed by warm weather.