Dropped leaves in soybean fields indicate soybean stem borers are feeding and causing leaf damage. These insects are expanding their range as a pest of soybeans in Nebraska and now can be found in several counties north of I-80.
New agricultural publications from Nebraska Extension include ones on fungicides for soybeans, a primer on cover crops, on-farm research results, agriculture in the Nebraska Panhandle, and ones on estimating soil water deep percolation or run-off.
Winter wheat harvest has been completed across most of Nebraska, according to the July 30 report from USDA’s National Agricultural Statistics Service. Significant rainfall of an inch or more was received across most of the state during the previous week and a few north central counties received as much as four inches of rain.
Spider mite populations are increasing in Nebraska. Fields should be scouted and the species correctly identified to provide proper management. Population levels should also be considered when treating fields with other insecticides that may knock out all natural predators, leading to population explosions of spider mites.
As conditions heated up the last two weeks, the fungus causing phytophthora root and stem rot became active in irrigated fields and those fields that received significant rain over the past couple weeks. Growers are encouraged to scout for this disease and, if found, manage through seed selection and treatment for the next crop.
Frogeye leaf spot is occurring in Nebraska soybeans, particularly in the eastern third of the state. While some fields have minor levels, some have significant levels and a fungicide treatment may be needed.
The persistent hot weather this growing season may be conducive to the development of charcoal rot disease in soybean and scouting is urged. Although charcoal rot is most severe in hot dry conditions, it can also cause losses when ample moisture is present, making it a hidden threat to yield.
Growers are reporting finding painted lady caterpillars and silver spotted skipper caterpillars in soybeans. This guide can help estimate leaf defoliation in soybean, key to determining whether treatment is necessary.