Running a sweep four inches below the top of the bed or power tilling the beds with L-shaped knives 3 to 4 inches deep before planting is effective in inhibiting nutsedge that has already sprouted. It is important to cultivate a second time for nutsedge after the crop has emerged. In the second cultivation, throw soil to the corn plants to help suppress nutsedge growth and allow corn growth to shade the furrow. Use the highest label rates for your soil type for the most effective control. Johnsongrass is a major problem in certain areas of California.
Prevention is the key to johnsongrass control.
Be especially diligent to prevent seedlings from becoming established. Once this weed is established on a farm, it is very difficult to eradicate. Johnsongrass seeds can get into irrigation water, manure, or lagoon water, and are easily spread throughout the farm. Ways to prevent its introduction are to ensure that feed is not contaminated with johnsongrass and to only use manure known to be well composted and free of weed seeds. If a johnsongrass infestation does occur, there are several options to choose from in the management of this weed.