North Dakota: Management of the Orange Wheat Blossom Midge (Sitadiplosis mosellana): The 1995-1996 Campaign

Challenge
Prior to 1995, no documented economic infestations of the Orange Wheat Blossom Midge existed in North Dakota. In 1994 and 1995, wet soils and wheat planting delays led to severe outbreak. In 1995, wheat head infestation levels ranged from 5 to 90 percent causing estimated yield losses of more than 7 million bushels.

Response
North Dakota State University (NDSU) entomologists and Extension agents educated farmers about this new pest. Cooperation with Canadian entomologists was crucial in compiling current wheat midge information. The project team implemented:

• two forums uniting university, producers and industry in a review of the wheat midge.
• a fall soil survey, which surveyed approximately 60 percent of the state, for detection and estimation of overwintering wheat midge larvae.
• February distribution of a map illustrating the density levels of midge larval cocoons.
• management recommendations distributed via various meeting and media formats, including daily updates to producers on activity within their region.
• Information delivery utilizing e-mail groups, the Data Transmission Network (DTN), the WWW and newsletters.

Results

• In 1996, delayed planting due to wet weather and overwhelming populations midge larval cocoons put almost 2 million North Dakota wheat acres at high risk
• Growers and the ag industry successfully responded to what midge
• Growers effectively used field monitoring, degree day information and use of treatment thresholds of one adult midge per four to five wheat heads.
• As a result, only 40 percent of the 2 million acres potentially at high risk were treated with an insecticide for wheat midge.
• Based on degree day accumulations and scouting, treatment activities ceased after 90 percent emergence of midge. This protected the beneficial parasitoid which becomes active shortly after midge activity peaks.