2013 Wheat Midge Forecast

The wheat midge forecast for 2013 indicates an increase in midge risk. Pockets of moderate to high risk are found in central and southern Alberta. Throughout central and southern Alberta individual fields could have a high population even if the forecast in the area is low. Producers should pay attention to midge downgrading in their wheat samples and use this as a further indication of midge risk in their fields. Wheat midge was confirmed in the Peace region in 2011 but the survey indicates that levels remain low there. Individual fields throughout Alberta may still have economic levels of midge. Each producer also needs to assess their risk based on indicators specific to their farm.

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The 2012 fall survey included wheat growing areas throughout Alberta. The survey was expanded to all wheat growing areas of Alberta in 2011 including the peace region. In total 297 samples were taken from 57 counties. The survey involves taking soil samples from wheat fields after harvest using a standard soil probe. Larval cocoons are washed out of the soil using a specialized series of screens. Larvae are counted, and then dissected to determine if they are parasitized. The midge density displayed on the forecast map is based on viable (live, non-parasitized) midge larvae.

This forecast is not intended to take the place of individual field monitoring. The forecast for Alberta shows areas of risk for midge damage in 2013. It is important to note that over such a wide range, populations in individual fields can be and often are highly variable. Producers should plan to monitor their fields when the midge adults are flying and their wheat is in the susceptible stage. In all areas where midge is present growers are urged to monitor their wheat fields from wheat head emergence to anthesis (the susceptible stage). Regular field scouting on multiple nights in succession is important in understanding the population in a particular field.

Although a number of factors influence the overwintering survival of the midge, the survey and map provide a general picture of existing densities and the potential for infestation in 2013. Weather conditions, specifically temperature and moisture will ultimately determine the extent and timing of midge emergence during the growing season. Temperature and wind also play critical roles in egg laying activities of the adult female wheat midge. The level of damage from wheat midge is determined by the synchrony of wheat midge emergence and wheat coupled with the number of wheat midge.

It is important to understand that once midge has established in an area it unlikely to ever completely disappear. Low lying and moist areas in a field provide a refuge, enabling the population to survive even when conditions are not favorable in the rest of the field. These low population levels, however, also help sustain a population of natural enemies.

The wheat midge survey was conducted by Alberta Agriculture and Rural Development with assistance from:

Solar Agri Services Ltd	Battle River Research Group
Chinook Applied Research Association	Lakeland Applied Research Association
Northern Peace Applied Research Association	Smoky Applied Research and Demonstration Association
Leduc County	Mountain View County
Parkland County	County of Two Hills
MD Wainwright	Agriculture and Agri-Food Canada, Beaverlodge Staff
Pest Surveillance Branch AARD