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New technique developed to assess number of CSFB larvae/plant

Innovation Centres

Max Hazell, Syngenta Trialist, has developed a new technique to assess the numbers of cabbage stem flea beetle larvae in oilseed rape stems.The plants were taken from Syngenta plots at our Rougham Innovation Centre.

Whole plants were cut at the base (10 plants/plot), then taken to the glasshouse where they were placed through ‘chicken wire’ over trays of water. The plants were left in a warm, sunny position to dry out for a week to 10 days.

In the field the larvae would leave the dying plants and drop to the soil because the plant is no longer feeding them, but in this case they drop into the water (which has a little ‘fairy liquid’ in, so the larvae sink!). After another week, the plants are discarded and the water is drained away to reveal the number of larvae/plant.


This then gives a very visual idea of the number of larvae.

CSFB Larvae

In this trial there were between 8-30 larvae/plant where the threshold is 5 larvae/plant.

Farmers be warned, even if your field looks healthy, it’s worth checking for larvae. The farmer’s own field was also tested and the results revealed 28 larvae/plant!