Searching IPM control measures for cabbage and turnip root flies on swedes

Abstract: In field experiments 2012-2013 different control measures against cabbage root flies (Delia spp.) were tested on swede. In addition to the chemical control program of the farm, insect net, GF-120 fruit fly bait and Steinernema feltiae nematodes in two concentrations were tested. Control plots were not totally untreated: to ensure the survival of the seedlings from the early flea beetle attack the control plots were treated with pyrethroids in the beginning of the season. Row-column design was used to manage the possible two-dimensional variation within the experimental field. In October, all the swedes were harvested in the middle of each plot (3 × 2 row meters), washed, weighted, and evaluated for root fly damage. Insect net was clearly the most effective method to reduce root fly damage in swedes. The probability for root fly damage was lowest under insect net in both years (11.6% and 1.3%) whereas with other methods it varied between 20 to 40%.