Grasses Weeds

Organic Weed Control in No-Till Vegetable Systems

Japanese stiltgrass is an invasive grass that is typically seen in wooded areas. It likes shaded, wet areas and can easily take over the forest understory. Unfortunately, it can also creep into pastures and hay fields. The leaves of Japanese stiltgrass are wider and shorter than most of our common pasture grasses. There is also a distinctive silvery midvein that is slightly off-center from the middle of the leaf (Figure 1).

Organic vegetable growers have a hard time managing weeds, as there are no reliable Organic Materials Review Institute (OMRI) chemicals for controlling grass or broad leaf weeds. Most of the time growers depend on tillage for weed control, but excess tillage can lead to destruction of soil structure and the loss of carbon from the soil. No-tilling cover crops is a possibility, but has several problems, most notably being unreliable as a season-long weed control method.

Starting clean, or weed-free, is a critical component of any weed management program. In 2022, growers experienced either a lack of or higher cost of glyphosate-based herbicides that are typically used to control weeds prior to planting soybean. In a study sponsored by the Maryland Soybean board and conducted at the University of Maryland’s Central Maryland and Wye Research and Education Centers, different glyphosate-based and non-glyphosate based herbicide treatments were evaluated for their ability to provide effective preplant weed control (Table 1). These treatments included both single and sequential herbicide applications.