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What is Cabbage Root Fly?
Posted by Suttons Staff on 26 July 2013 08:54 AM

Cabbage root fly is a common pest of cabbages and other brassicas such as cauliflower, broccoli and brussels sprouts.
Established plants can normally withstand slight to moderate attacks although growth may be slow and yields low. Seedlings and young plants are the most vulnerable.

The larvae of the cabbage root fly feed on the fine roots of the plant until just the rotting stem remains. The plants wilt or grow slowly and are easily pulled out of the soil, the leaves may be tinged blue-red. Cabbages may fail to heart and cauliflowers produce small heads.

Thorough cultivation of the soil in winter will help to reduce the numbers of over wintering pupae.

Infestations can be reduced by placing fibre 'collars' around plants immediately after planting, we recommend these cabbage collars . The female flies lay their eggs on the collar instead of the soil, they then dry up before hatching.

Protection of the young plants can be achieved by covering the crop with fleece such as our Envirofleece or with a fine mesh netting such as Enviromesh. Ensure that the edges are buried to prevent entry by the flies. If the plants are planted in a small hollow they can be earthed up to encourage new roots should an attack occur.

It is possible to control cabbage root fly using biological control such as the excellent 'Grow Your Own - Multiple Pest Killer' product from Nemasys.

This is carried out from April to July by watering nematodes onto the soil around the root area.

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