Ryegrass demonstrates a unique quality to control the growth of other plants – such as the infamous Palmer amaranth or Palmer pigweed. The dense cover of ryegrass can suppress weeds or plants that may have an adverse effect on the crop yield and quality. Weed suppression through competition from a late season cover crop such as ryegrass has proven to be more effective than planting a combination of just oats and rye alone.
During the Fall of 2013, oats and rye were planted on a prepared seedbed, but this time certain areas were over-seeded with ryegrass because the farmer (we worked with) had some left over seed.
To use ryegrass to suppress pigweed follow these protocols:
Plant in prepared seed beds or over-seed pastures free of actively growing weeds.
For crops other than permanent pastures, use no-till technology to prevent disturbing the soil and reduce weed seed germination.
Provide for the nutritional needs of the ryegrass crop.
At the end of the ryegrass growing season, use residual for hay, mow or graze close and employ a herbicide program to control pigweed and other summer weeds.
A weed management program using ryegrass as a suppression tool should be followed with the use of a pre-emergent and post-plant herbicide program to significantly reduce the population of pigweed.