Scientists at ADAS and East Malling Research have come up with a novel way of using bumble bees to deliver minute quantities of bio-fungicide to strawberry flowers.

Grey mould (Botrytis cinerea) is a very damaging disease to strawberry crops worldwide. Symptomless infections can develop in strawberry flowers and cause fungal growth on fruit as they ripen and after picking. Control currently consists of careful management and conventional crop protection products applied to flowers to protect against infection.

ADAS and East Malling Research, (as part of a five year Strawberry HortLINK project sponsored by Defra and funded by HDC and industry representatives) have been testing a novel approach to grey mould control using bumble bee pollinator hives which are already commonly introduced to commercial strawberry crops to ensure good pollination.

The experimental approach (not yet approved in the UK) involves the bees moving through a specially designed dispenser which fits into the hive. As the bees move through the dispenser a minute quantity of a powdered formulation of the bio-fungicide containing Gliocladium catenulatum adheres to their bodies and legs. As they leave the hive and begin pollinating they transfer the powder directly to the flowers, allowing a very precise application of this bio-fungicide throughout flowering. The bio-fungicide, which is itself a fungus, competes for living space with the grey mould on the flower parts, preventing the latent flower infection which causes the fruit to rot.

During the last two years of field trials this harmless bee-delivered control system was demonstrated to be a practical alternative to fungicide applications and regularly achieved levels of grey mould control equivalent to areas treated with fungicides while significantly decreasing any residue left on the fruit itself.

Data from this HortLINK project and ongoing trials in Finland and Belgium, where this technique is already being adopted will be used to support an application for pesticide registration of this fungicide dispersed by bees in the UK. ADAS hopes to carry out further trials to develop this novel strategy further.