How do we control horsenettle in commercial blueberries?
This has become a real issue in hand-harvested fields.
Van Buren County Michigan
Most of the commercial herbicides registered in blueberries are ineffective against horsenettle. Sinbar has good activity; Stinger and Callisto are fair. I would suggest using Sinbar in your herbicide rotation this spring. The recommended rate for Sinbar 80WDG is 1 to 2 pounds per treated acre. I would start with the one pound rate next spring if you have sandy soils and look at the impact on the horsenettle population and the blueberries. Sinbar can be pretty hot on blueberries but a spring and fall application of one pound would maintain soil active levels without going as high as the 2 pound rate.. I like herbicide combinations so I would suggest Sinbar mixed with Callisto or another material for maximum effect and control of a broader spectrum of weed species.
Eric Hanson has written several blueberry herbicide articles but none focus specifically on horsenettle. Here is a link to a general one; then you can search MSUE.News for more using the search box in the extreme upper left and typing in "Blueberry weed control."