Content by Adam Varenhorst
Monitor Newly Emerged Corn for Black Cutworm Activity
There are several important insect pests that can severely injure corn during the early vegetative stages. One of these pests is the black cutworm. Although black cutworm caterpillars injure corn by feeding on leaf tissue, the serious damage occurs when caterpillar feeding results in the cutting of young corn plants.
Winter Wheat Disease Update: Wheat Streak Mosaic and Tan Spot Developing at Low Level
Winter wheat fields scouted the week of May 27, 2019 in South Central South Dakota were found with wheat streak mosaic virus and tan spot developing at very low levels. Both diseases were found in non-rotated wheat fields.
Watch Corn for Bronzed Cutworm Activity
Bronzed cutworms are not a common pest of corn in South Dakota. However, they can become an issue when corn is planted into areas that were previously grassland. Like its name implies, bronze cutworms feed on corn above the soil surface, which often results in cutting or clipping.
Common Stalk Borer Activity Update: May 23, 2019
Not too much is new regarding common stalk borer activity when compared to last week. Another cool, wet week has led to a limited accumulation of degree days. Based on our calculations, common stalk borer activity still doesn’t warrant any scouting. We will continue to monitor the degree days and provide updates.
2019 Alfalfa Weevil Activity
It was another cool week in South Dakota with not a lot of degree day accumulation occurring. Alfalfa fields should still be monitored for alfalfa weevil activity even though the cool wet weather might have slowed this pest down.
Soybean Gall Midge: It’s a New Species!
Researchers recently determined that the soybean gall midge, discovered in South Dakota in 2015, is actually a previously undocumented species. The origin of the new species, Resseliella maxima Gagné, is still unknown.
Alfalfa Mosaic Developing in a Few Alfalfa Fields
In South Dakota, alfalfa fields that were recently scouted were found to be infected with Alfalfa mosaic virus (AMV) at a very low incidence. AMV is a common virus in alfalfa that can also infect soybeans.
Common Stalk Borer Activity Update: May 16, 2019
The hatching and movement of common stalk borer caterpillars can be estimated by using degree days with a developmental threshold of 41 degrees Fahrenheit. Common stalk borer eggs typically begin to hatch at 575 degree days.
How to Identify Common Stalk Borers and Thresholds
As corn is being planted, it is important to remember that there are insect pests capable of injuring young, vegetative corn. One such pest is the common stalk borer. Although common stalk borer outbreaks are sporadic, when present in high numbers they can cause significant yield loss.
Grasshopper Mites in South Dakota
Fact sheet that covers the ectoparasite grasshopper mites.