Why Are My Gooseberries Going Grey and Mouldy?

Gooseberries that soften, turn grey, and develop a furry grey-brown coating are infected with botrytis grey mould (Botrytis cinerea). This opportunistic fungal disease is one of the most common problems on soft fruit in cool, wet summers and can destroy a significant portion of the crop on heavily infected bushes. It enters through wounds, dead flowers, or stressed tissue and spreads rapidly in damp, still air.

How botrytis infects gooseberries

The fungus produces billions of grey-brown spores that are present in the air at all times, but it can only infect when conditions are right — particularly when fruit is damaged or when temperatures are cool and humidity is high. The most common point of entry is through the dried, dead flower that remains attached at the fruit's blossom end. The fungus grows from the dead flower into the developing fruit. Other entry points include skin damage from thorns, birds, or insects. The grey fluffy coating is the sporulating fungal growth, and it is highly infectious — touching an infected berry and then a healthy one can spread the disease.

Removing infected fruit

Pick off all affected berries as soon as you notice them, handling them carefully to avoid releasing spores onto healthy fruit. Dispose of them in the bin rather than the compost heap, as botrytis spores survive composting. Collect any fallen affected berries from the soil surface promptly. If the weather is wet, check the bush every day or two during the harvest period and remove any berries that are beginning to soften before the full grey mould develops.

Improving air circulation

The most important preventive measure is ensuring good air circulation through the bush. A congested, overcrowded bush where the interior is dense and humid is ideal for botrytis. Annual pruning to maintain an open goblet structure with a clear centre reduces humidity within the canopy significantly. Remove any dead wood, as dead tissue is a primary colonisation point for the fungus. Do not grow the bush in a sheltered corner with no air movement.

Watering and mulching practice

Avoid overhead watering that wets the foliage and fruit during the harvest period. Water at the base of the bush rather than over the top. Avoid mulching right up to the main stems, as moisture retained at the base of the stems can encourage botrytis at the crown. A gap of 5–10 cm between the mulch and the woody stems is advisable.

Harvesting promptly

Gooseberries that are left on the bush past peak ripeness become progressively more susceptible to botrytis infection as the skin softens and any small skin breaks provide entry points. Harvest promptly when fruits reach full ripeness, particularly in wet weather. If the weather turns very wet and cold during the harvest period, pick the whole crop and store or process it quickly rather than leaving the fruit hanging on the bush for several more days.