Causal Agent: 

Oomycete (Pythium spp.)

 

Characteristic Symptoms:
 
The part of the stem near the soil surface turns brown, becomes water-soaked, soft and slender and then collapses.
   
Young seedlings topple down due to root rotting and weakened stem.
   
In pre-emergence damping-off, germination of seed is greatly reduced.
   
Conditions for Disease Development:
 
The disease is common in cool, wet soils.
   
All crops are susceptible usually at seedling (3 weeks after sowing) or early vegetative stage.
   
Over watering or poor drainage, over crowding of plants, excessive application of nitrogen, stressful environmental conditions and presence of nematodes may contribute to susceptibility.
   
The pathogen is disseminated through contaminated irrigation water, splashing rain or heavy rainfall.
   
Management and Control:
 
Use pathogen-free/certified seeds.
   
Drench nursery beds/seedling trays with chemical fungicides  like promocarb hydrochloride (e.g. ProplantⓇ, PrevicureⓇ) or fosetyl aluminum (e.g. AlietteⓇ), metalaxyl+mancozeb (e.g. Ridomil Gold MZ 68 WGⓇ, Apron XL 350 ESⓇ), mancozeb (e.g. Attain M-80Ⓡ, Achem Mancozeb 80 WPⓇ, Micron 80 WOⓇ, VanzebⓇ).
   
Clean thoroughly seedling trays and pots and soak in 10 mg/L chlorine.
   
Avoid over watering or excessive moisture.
   
Expose beds to solar radiation to minimize fungal population.
   
References:
Compendium of Cucurbit Diseases (1996) by the American Phytopathological Society
   

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