Quackgrass (Agropyron repens) Interference on Corn (Zea mays)

Abstract

Field studies were conducted to evaluate the effect of quackgrass [Agropyron repens(L.) Beauv. ♯ AGRRE] density and soil moisture on corn (Zea maysL.) growth and yield. Quackgrass densities ranging from 65 to 390 shoots/m2reduced corn yield 12 to 16%. A quackgrass density of 745 shoots/m2reduced corn yields an average of 37% and significantly reduced corn height, ear length, ear-fill length, kernels/row, rows/ear, and seed weight. In the soil moisture study, quackgrass was shorter than corn throughout the growing season, and analyses of corn leaf tissue indicated that quackgrass did not interfere with the nutrient status of the corn. In 1979, soil moisture was not limiting and corn yields were similar in all treatments regardless of irrigation or the presence of quackgrass. In 1980, soil moisture was limited and irrigation increased the yield of quackgrass-free corn. Irrigation also increased the yield of quackgrass-infested corn to a level similar to irrigated corn. When light and nutrients are not limiting factors, an adequate supply of soil moisture can eliminate the effects of quackgrass interference on the growth, development, and yield of corn.