Updated phenology models for insect pests on the Canadian prairies will be posted to our new Predictive Model Update page during the growing season, as they become available. This information is intended to supplement the Weekly Updates while providing the most current information to further support in-field scouting.
Whenever items are posted to this page, @vanbugsky will be Tweeting and using #PPMNblog to help users access this most up-to-date information.
This week, an updated table of predicted emergence dates for bertha armyworm was posted for across the Canadian prairies (May 30, 2018). Those in charge of coordinating deployment of pheromone traps will need to pay particular attention to these dates.
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.
Swede midge (Contarinia nasturtii) – The Swede midge bioclimate model was run for Melfort for 2015 and 2016 (April 1 – August 7). For 2015, model output indicated that the 2015 growing season would have resulted in two generations by the first week in August (first graph below). For 2016, model output indicated that there has been potential for four generations in the 2016 growing season (second graph below). The extra generations in 2016 are explained by timing of rainfall. Adult emergence is delayed until a) the required number of degree-days are achieved and b) after at least 10 mm of rain has occurred (over a 7 day period). In 2015, low rainfall during April and May resulted in delayed emergence with first adults emerging in early June. A dry period in late June/early July was predicted to delay adult emergence until mid-July. In 2016 May rainfall was predicted to result in adult emergence occurring during the second week of May and subsequent emergence in mid-June, mid-July and early August.