Brassica pod midge in winter oilseed rape: strategy for control
1994
Hansen, L.M.
Brassica pod midge (Dasineura brassicae) is a major pest in oilseed rape (Brassica napus) mainly in winter oilseed rape. In recent years Brassica pod midge occurrences have been fairly limited and the need for control has varied considerably. An important information is time of flight activities of the 1st generation. The present paper deals with an experiment attempting to describe a method of determining this time and contains a short discussion of control strategies. In 1993 a plot experiment was set up at the Danish Institute of Plant and Soil Science to find optimum time of spraying against Brassica pod midge in winter oilseed rape. The experiment included one untreated control and six plots each treated at different times. Beginning flight activities took place after about 80 deg DD with 8 deg C as basis temperature and average flight activities took place after 110 deg DD. A single control on 10 May gave a significant effect on the number of pods attacked but not on the final yield. As it will appear from Fig. 1 about 6 Brassica pod midges/day/trap were caught in connection with the flight activities of the 1st generation whereas the flying activities of the 2nd generation were about half as large. Beginning flight activities of the 2nd generation took place after about another 270 deg DD. Furthermore a questionnaire was sent to 90 growers -24 replies. The investigation showed that generally the occurrence of Brassica pod midge was low. 75 % of the growers stated that less than 5 % of the pods were attacked in the field edge whereas only 8 % of the growers had more than 10 % attack
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