Additional fields from June 17 to 21 have been found with significant populations of cereal aphids. Infestations in west central Minnesota and on into northwest Minnesota are reaching treatable levels. Bruce Potter, UMN IPM Specialist in SW MN, is reporting treatable numbers found in fields in SW and SC MN. These infestations south of our region are usually a good indication of what will happen here. Begin scouting for aphids to monitor their progress in your own fields.Look for aphids on the undersides of the leaves and in the leaf axils.
To protect small grains from yield loss due to aphid feeding, the Treatment Threshold is 85% of stems with one or more aphids present. If you have a strong desire to count aphids, then treat when you AVERAGE 12-15 aphids per stem. Treatment decisions for aphids are most critical in growth stages prior to complete heading. After heading is complete, the potential for aphids impacting yield is significantly reduced. The best results for treating threshold levels of aphids is prior to heading.We suggest field scouting for aphids continue up to the heading stage of wheat.
Cereal aphids do not overwinter in our region, but migrate into the area on northward winds. It's good insurance to scout early and look for any symptoms of barley yellow dwarf virus (BYDV) in wheat. BYDV causes stunting of plants and yellow or red leaves in barley and wheat. BYDV vectored by aphids causes plant stunting, small heads, shriveled kernels and reduced yields. Bird cherry-oat aphid is the main vector of BYDV, but English grain aphid will also vector BYDV.
Aphid feeding on young plants in the seedling stage can also cause reduced plant growth and adversely affect plant health. The greatest risk of yield loss from aphids feeding on grains is in the vegetative to boot stages. Avoid spraying any preventive sprays or spraying too early, because this will disrupt the natural enemies that keeps aphids in control naturally. Lady beetles, aphid lions, syrphid fly larvae, and parasitic wasps play a major role in reducing aphid populations. When natural enemies are present in large numbers, and the crop is well developed. farmers are discouraged from spraying fields. When it is necessary to use insecticides; use only recommended sprays.
For a review of recommended insecticides for aphid management in small grains, a good summary is available in the 2013 North Dakota Insect Management Guide
View regional maps summarizing current observations in
Wheat and Barley
The Minnesota Association of Wheat Growers has assembled numerous links to resources available on the web that relate to small grain production. At this time, we suggest you access their resources.
They can be found here
WWW-F0-02547, UMN Extension
PP-1361, NDSU Extension Service