2021 Weed Suppression in Field Pea Using Intercropping after Herbicide Group 2 Application

Field pea is a poor competitor crop. As a temporal solution to control faster growing weeds and alleviate competition, fields are sprayed with Group 2 herbicides which have shown to cause herbicide weed resistance. It is hypothesized that if the seeding rate is increased, yield will be compensated despite weed competition. In addition, if field pea is intersown with cover crops, there is greater weed suppression. This is an economic advantage as it removes the necessity for herbicide application and inclusion of cover crops supply additional organic matter to the soil. This two-year split block experiment consisted of a Group 2 herbicide (in this case REFINE SG) application to spring wheat. Plots were either sprayed with the herbicide at 12 g ac-1 or left untreated. The following year, field pea was sown at three different seeding rates (90, 180 and 270 lb ac-1). Each of these rates were either sown alone or intersown with either annual rye, barley, oat and rye at 5, 35, 35, and 17 lb ac-1. Weeds were counted using 25 cm quadrats every two weeks and grouped as either broadleaf or grass.