Sclerotinia

Description

The first symptoms are light-brown patches on plant stems, branches and pods. Those lesions grow over time and become greyish-white. Infected plants stand out because of their bleached appearance. As the infection progresses, parts of them wilt and become mouldy. If conditions stay wet or humid, a white fungal growth that looks like cotton wool may also develop on the infected stems.

Sclerotinia – the resting bodies that can survive in the soil for up to six years and carry the disease into subsequent seasons – resemble rat droppings.

Control

Management decisions should be based on an assessment of disease risk that takes into account the paddock history. If canola was grown and affected by sclerotinia in the same paddock within the last five years, the risk of infection will be quite high. If retained seed from a previous crop that was infected is being used, it should be cleaned and closely inspected to make sure it is free of sclerotinia.

When there is a known disease risk and weather conditions at flowering are conducive, spraying Prosaro® at 20–30% flowering – before any signs of infection appear – will provide both effective protection and an economic return.