EFFECT OF TILLAGE AND GLYPHOSATE ON CONTROL OF QUACKGRASS (ELYTRIGIA-REPENS)

Field studies were conducted during two soybean-corn rotations to eval uate the effect of tillage systems on quackgrass growth and control wi th and without glyphosate. In the final year of the study, tillage alo ne (compared to no-till) resulted in 88%, 78%, 64%, and 31% control of quackgrass with fall moldboard plow, spring moldboard plow, fall soil -saver, and spring soil-saver tillage, respectively. When glyphosate w as used to control quackgrass, crop yields increased as tillage was re duced and excellent control of quackgrass in no-till was achieved. Inc reased shoot growth (in moldboard plowed and fall soil-saver tillage p lots), exposure of rhizomes in winter (in fall tilled plots), and incr eased depth of rhizome burial (in spring tilled plots) increased quack grass control. In general, the total biomass of quackgrass was reduced in drier years. Nonetheless, drought increased crop yield losses caus ed by quackgrass interference. Nomenclature: Quackgrass, Elytrigia rep ens (L.) Nevski. #3 AGRRE; glyphosate, N-(phosphonomethyl)glycine.