Populations of immature grasshoppers have been reported in areas bordering crop fields. If you're seeing one of the four species that harm cropland noted here, control may be warranted. Treatment is most effective when grasshoppers are small and still contained in field borders.
Corn and soybean growers should be scouting for Japanese beetles, which have started emerging in eastern Nebraska. First identified in counties along the state's eastern border several years ago, the beetles were found as far west as Lincoln County in 2016.
Ag professionals across central and eastern Nebraska are reporting insect damage to corn following rye and wheat cover crops, likely from the wheat stem maggot. A recent field survey found stand losses in fields ranged from 2%-30% on a whole-field basis.
UNL Extension Entomology is monitoring crop insect pests (primarily moths) using black light traps at the Haskell Ag Laboratory near Concord, the South Central Ag Laboratory near Clay Center, and the West Central Research and Extension Center near North Platte.
Palmer amaranth has not been confirmed in conservation plantings in Nebraska; however, the identification and occurrence of Palmer amaranth in CRP fields in Iowa has raised concerns among weed scientists and growers about its spread into conservation plantings in Nebraska and offer some suggestions for growers.
As corn begins to emerge, be alert to the potential for damage from early season insects such as cutworms, wireworms, or white grubs. Wireworms and white grubs are most often associated with fields that have been in pasture or CRP where the grasses were allowed to grow for more than one year. It is rare to see these problems in continuous corn, but exceptions happen. Since wireworms and white grubs feed underground and cutworms feed on or below the soil surface, scout for plant damage and then dig in soil around the plant to identify the insect causing the damage.
Alfalfa weevils have been reported damaging alfalfa in north central Kansas and western Nebraska. As temperatures warm up, expect to see alfalfa weevil larvae in southern Nebraska and slightly later, in northern Nebraska. Even with the pressure of planting row crops, it is essential that producers growing high quality alfalfa hay make time to monitor fields for weevils now and over the next few weeks. See the article for a table of treatment thresholds for various alfalfa prices.