Science - November 17, 2005

Bee with fungus fights brown rot

Researchers at Applied Plant Research (PPO) and Plant Research International (PRI) have carried out successful tests to control a plant disease by giving fungi to honeybees.

The researchers used bees to control the fungal disease botrytis, brown rot, in strawberries. Brown rot is a big problem for strawberry growers: parts of the plants die off as they become covered in grey mould.

The researchers developed a beehive with a special entrance, where the bees pick up a small amount of powder fungicide as they leave the hive. In this case it was a biological fungicide, ulocladium, a fungus itself and a natural enemy of botrytis. ‘The method works well. The bees brush the powder off a bit, but some always remains on their legs or wings,’ said Dr Lonne Gerritsen of PPO Bees. The beehives were placed next to strawberry test plots.

The bees go in search of nectar in the flowers of the strawberry plants, which is exactly where botrytis usually starts spreading, and leave a bit of the ulocladium fungus behind. This destroys the botrytis within a few weeks. The bees take the fungicide right to the source of the disease. This is less wasteful than spraying crops, where quite a lot of the fungicide does not even land on the plants.

The bee researchers are enthusiastic, although they say there are still drawbacks. The method can only be used for diseases that start in the flowers, and the fungicide must be available in powder form and not be harmful to bees. The method still needs to be tested on a bigger scale. As things stand, bees can only be used in addition to spraying fungicides. / HB

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