Watch for Midge as Wheat Approaches Heading Stage
July 1, 2009 7:21 PM
by Phillip Glogoza, Extension Educator - Crops
There could be about 70% of the region's wheat acres at the heading stage when wheat midge are emerging, based on those acres being planted in the high risk window (Figure 1). Heading is the growth stage when wheat is attractive to female midge for egg laying, and the time the plant is most susceptible to injury from midge larval feeding. Though midge populations have been small in recent years, this will be the most wheat acres we have had that are susceptible to midge in many years.
Based on degree day accumulations, wheat midge should be emerging in the southern counties of the spring and durum wheat region (Figure 2). The oldest wheat fields have begun heading. Midge should begin emerging in the central areas over the weekend, and by the middle of next week in the northern areas.
Wheat midge must be scouted in fields beginning at dusk. If temperatures drop below 59 F, or wind speed is greater than 6 mph, the midge will stay low in the crop canopy and will not be found. The frail, orange-colored midge will fly slowly in the canopy, moving toward the wheat head where they will land to begin egg laying. Scouting requires that midge numbers per wheat head be estimated.
The treatment threshold for controlling midge is:
Hard Red Spring Wheat = one or more wheat midge for every 4 or 5 heads
Durum Wheat = one or more wheat midge for every 7 or 8 wheat heads