The midge is an important pest of wheat and, to a lesser extent, other cereal crops in Montana. Wheat is most susceptible to midge damage when egg-laying occurs from early heading through flowering. These stages and how to identify them are described below.
Note: you can click on the images to enlarge them.
The boot stage is the earliest growth stage that we are concerned about. The midge does not cause any crop damage during the boot stage, but it is at this stage that monitoring efforts should begin. Early boot is characterized by a swollen leaf sheath below the flag leaf. Late boot is characterized by the flag leaf sheath opening and awns becoming visible at the leaf collar. Late boot stage is pictured.
Heading is characterized by the emergence of the heads/spikes on the plants. Heading is defined by the percent of the head/spike exposed above the flag leaf collar for 50% of the crop. For our purposes this is broken up into three stages: early (25% headed), mid (50% headed) and late (75% headed). A plant in the early headed stage is pictured on the left and a plant in the late headed stage is pictured on the right.
During flowering greenish-yellow anthers appear on the head/spikes. Flowering usually begins in the center of the head and progresses outward toward the ends. Once again this is divided up into three phases, early, mid and late. In this case however it is the percentage of the head on which anthers have emerged for the majority of plants which defines the stage. Early flowering has anthers over 25% of the head, mid flowering has anthers covering 50% of the head and late flowering has anthers over 75% of the head. A plant in the late flowering stage is pictured.
The end stage is defined as flowering being complete on the majority of the crop.