Friday, 19 August 2016

Weekly Update (August 17, 2016; Wk 16) - Swede midge (updated)

Swede midge (Contarinia nasturtii- This growing season, bioclimatic model outputs predicting swede midge development continue to be compared to in-field observations of actual midge in canola in Saskatchewan since the model has yet to be validated with midge data from that region.

The model was run for Melfort SK for April 1 – 14 and the output suggests 4 generations might possibly occur in 2016 in northeast Saskatchewan.

Warm, wet conditions are predicted to result in shorter generation times in July and August than May and June.

In-field monitoring continues to be the priority both to detect new populations of swede midge on the prairies but then to validate the number of generations and phenology of this pest relative to canola development on the prairies.    
Swede midge scouting tips for in-field monitoring:

• Watch for unusual plant structures and plant discolourations then follow-up by closely scrutinizing the plant for larvae.
• The growing tip may become distorted and produce several growing tips or none at all, young leaves may become swollen, crinkled or crumpled and brown scarring caused by larval feeding may be seen on the leaf petioles and stems.
• Flowers may fail to open.
• Young plants that show unusual growth habits should be examined carefully for damage and larvae; especially if the sticky liners have many flies resembling midges (swede midges are about the size of orange blossom wheat midge but are not orange).
• Larvae can be seen with a hand lens.
• Refer to the Canola Watch article by Dr. Julie Soroka for more information on swede midge and watch for a new Ontario fact sheet produced by Baute et al. 2016.