DiseasehighMay–Sep

White mould (sclerotinia)

Sclerotinia sclerotiorum

This description was machine-translated.

How to spot it

White mould is caused by the fungus Sclerotinia sclerotiorum and attacks many vegetable crops, especially lettuces and beans. Typical is a cottony, white fungal growth at the base of the stem that develops into black, irregular resting bodies (sclerotia). Infected plants wilt suddenly even though the soil is moist, because the inside of the stem rots soft and watery. The sclerotia survive in the soil for years and germinate again in damp, cool weather.

Prevention

Go for wide planting distances and airy positions so that the foliage dries quickly, and avoid waterlogging by keeping the soil loose and well drained. Plan a crop rotation of at least three to four years with non host plants such as cereals or alliums. Remove infected plants together with their root balls immediately and completely from the bed instead of composting them, so that no new sclerotia build up in the soil. Water in the morning and at the base, so that the leaf base does not stay permanently wet overnight, and keep the stand open by thinning in good time. Where you know the disease pressure is high, choose tougher varieties and let badly infected areas rest for one to two years under crops that are not susceptible.