Bean Leaf Beetle Biology and Management

In the past few years, Iowa bean leaf beetle densities have reached record levels. Bean leaf beetles are present in Iowa soybean fields every year, but recently many producers have had to apply insecticides to manage this pest

Integrated Pest Management—Stalk Borer Ecology and Pest Management Options in Corn and Soybean

Stalk borers can heavily infest crops that are adjacent to grass terraces, fence lines, or grass waterways and cornfields. Cultural and chemical management techniques are discussed.https://lib.dr.iastate.edu/extension_ag_pubs/1182/thumbnail.jp

Spider mites are burning soybean fields

Twospotted spider mites can become serious pests of soybean whenever hot, dry weather persists. We have confirmed reports from Lee and Wapello counties in southeastern Iowa where fields have been sprayed because spider mites are burning the leaves and causing plant defoliation. The twospotted spider mite is named for the two dark spots on the sides of the abdomen, which are digested food visible through the insect\u27s translucent body. Three or four spots may be apparent and are most prominent on adult mites

Two-spotted spider mites on soybeans

Twospotted spider mites, Tetranychus urticae, are serious pests of many crops throughout the United States. Whenever hot, dry weather persists, large spider mite populations may develop on both soybean and corn. Producers in areas of Iowa where the weather remains dry should be on the lookout for spider mite infestations. Dale Schwade (A and K, Lime Springs) reported a 20-acre soybean field with classic spider mite symptoms last week in Howard County

Soybean aphid biology

The soybean aphid was first reported in Iowa in 2000. It has survived the winter and colonies are now being found south of Decorah in Winneshiek County in northeastern Iowa. Aphid colonies were very small, often less than 10 aphids on a plant, and they were clustered on the underside of the newly developing trifoliate leaves. The aphids were difficult to find and checking 20 plants at random in several fields was not a large enough sample to detect these small population

Soybean aphid scouting and management

Management activities for most soybean insect pests consist of scouting, use of thresholds, insecticide applications when necessary, and prevention through cultural activities. Probably the most practical scouting method for soybean producers is to take soybean aphid counts on leaves. This method is useful for pest detection when insect densities are low

Insect odds and ends

Last week, there were some reports of uncommon crop insect pests active in Iowa. Black cutworm larvae were reported in fields in Fremont and Ida counties. Since the cutting forecast map published in the May 11, 1998 ICM (page 69), there have been several additional moth flights across Iowa. This means that larvae of different sizes may be found during scouting. Once corn reaches growth stage V4 to V5, black cutworms can no longer cause significant damage to the field

Ecological impact of herbicides associated with transgenic soybeans on spider mites

How do RoundUp® Ready soybeans affect the growth of fungi that may keep down the populations of some significant soybean pests? Experiments in the laboratory and soybean fields explored this question