Grey mould, also known as botrytis cinerea, is a disease that can run riot if given a chance, especially in a greenhouse. This fuzzy grey mould grows on buds, leaves, flowers and fruit, attacking injured or stressed plants. 

Grey mould’s airborne spores are always present, and thrive living on dead organic material, but can also infect living plants under certain conditions. However, the infection can lay dormant on some fruits until they begin to ripen and sugar levels rise.

How to spot grey mould

Early signs of grey mould include small brown spots forming on the skin of the fruit, which then spread over the whole fruit, turning it soft and brown. Grey mould has a distinct grey-brown or off-white fuzzy growth on the leaves, stems, fruits or flowers of plants. Other things to look out for are wilting, shrivelling and rotting tissue, indicating grey mould. 

Once a plant is infected, botrytis may spread to all parts depending on its species and variety.

How to treat grey mould

If the conditions are damp and cool, make sure you keep a lookout for early signs of grey mould. Remember, grey mould will attack any plant that has been injured, so remove dead or injured plant parts before they can become infected.

Grey mould on plants cannot be treated by fungicides. If your plants have already been struck with grey mould, then remove the infected areas immediately and cut back into a healthy growth. Be sure to keep weeds down and clear away any surrounding plant debris. Separate plants to avoid overcrowding and spreading of the disease.