Degree days for root, bulb and leafy vegetable pests – 22 May 2012

Thresholds for onion maggot fly emergence have been reached for all areas degree days have been calculated for (Bradford/Holland Marsh, London, Wellington, Windsor, Thedford, Delhi and Ridgetown). First generation adults of cabbage maggot should start to appear in the Windsor area. For other areas, except Wellington, cabbage maggot adults should start to appear in 5-7 days. If resident populations are present, carrot rust fly adults have begun to emerge in Bradford/Holland Marsh, London, Thedford, Delhi and Ridgetown areas. The threshold for carrot rust fly emergence should be reached in 1-2 days for the Wellington area. If resident populations are present, carrot weevil have likely started to lay eggs in all areas. Based on degree days, Tarnished plant bug should have started to emerge in all areas. Overwintering leafhopper eggs have likely started to hatch in all areas, except Wellington.

Here are the degree days accumulated from April 1st until May 22nd, 2012.

* Data provided thanks to Muck Crops Research Station, Department of Plant Agriculture, University of Guelph

Degree day information for pests