SR9088 - Management Strategies for the Swede Midge in Ontario Cole Crops

Researcher:

Dr. Rebecca H. Hallett, Dept. of Environmental Biology, University of Guelph

Objectives:

1. To examine life history parameters of swede midge in Ontario.

2. To evaluate varietal resistance/susceptibility to swede midge damage.
   

3. To evaluate efficacy of registered and/or new insecticides for control of swede midge.
   

4. To determine current range of swede midge in Ontario cole crop production areas.

Expected Benefits:

1. Generate new knowledge about an insect pest for which no North American information exists.
   

2. Management practices developed will help to reduce losses to this pest and thus to increase the competitiveness of the Ontario cole crop industry.
   

3. Information generated will provide urgently needed biological and control information to Ontario cole crop producers, crop scouts and extension personnel dealing with this problem.
   

4. Determination of the full and current distribution of the swede midge will help in planning strategies to limit the impact of the swede midge on the entire industry.
   

Summary of Research Results:

An accurate predictive model of swede midge development would allow growers to select and apply insecticides according to the present life stage; research activities have thus focussed on the validation of an existing European model for swede midge emergence, and the development of a new model based on Ontario conditions.

The model was tested over two field seasons (2003 and 2004) under Ontario field conditions, but was found to be inaccurate in predicting the occurrence of swede midge adults largely because the model is based only on temperature. As a result, researchers at the UofG have developed a new model that also incorporates moisture parameters, which are known to be important in swede midge development. The new model was constructed using DymexTM, specialized modelling software developed by the Commonwealth Scientific and Industrial Research Organization (CSIRO) in Australia. The new preliminary model more accurately predicts swede midge emergence throughout the entire season than the European model. This new model is currently being refined to increase its accuracy through developmental trials (planned for the 2005 field season) and validation with other swede midge population data.

Eradication of the swede midge is impossible, however with the aid of an accurate predictive model it is hoped that growers will be able to keep swede midge infestations below economically damaging levels. The validated model should be a stand-alone predictive tool for regional information on swede midge populations. The model may also be used in conjunction with well-maintained and routinely serviced pheromone traps and regular scouting by a qualified consultant to provide accurate information on the timing of swede midge population peaks on a local scale.

Management practices for the swede midge should incorporate both cultural and chemical control approaches. A minimum three year rotation to non-cruciferous crops and control of cruciferous weeds is recommended by the International Swede Midge Taskforce to prevent escalating swede midge populations. Standing crop residues should also be chopped and deep-ploughed as promptly as possible to prevent further development of swede midge and high overwintering populations.

For more information on this and other swede midge research activities, please contact: Dr. Rebecca Hallett, Department of Environmental Biology, University of Guelph, Guelph, ON, N1G 2W1; (519) 824-4120 ext 54488; rhallett@uoguelph.ca.