Quackgrass (Agropyron repens) Biotype Response to Sethoxydim and Haloxyfop

Abstract

Crown bud, tiller, and rhizome development was studied in 10 quackgrass biotypes at two stages (three-to four- and seven- to eight-leaf stages) of development to determine if differential development of these structures influenced control with sethoxydim and haloxyfop. There was a differential response among the 10 biotypes to both sethoxydim and haloxyfop at both stages of development. The biotypes differed in the number of crown buds, tillers, and rhizomes that formed at both stages of development. In the three- to four-leaf stage, the biotypes with the greatest number of crown buds were the most difficult to control. These results suggest that in the susceptible stage (three-to four-leaf) the quackgrass biotypes with the least number of crown buds will be the easiest to control; however, by the time all the biotypes reach the seven- to eight-leaf stage even the biotypes with the lowest number of crown buds have enough crown buds that they become difficult to control with either sethoxydim or haloxyfop.

Herbicide Effects on Established Yellow Old World Bluestem (Bothriochloa ischaemum)

“…Chao et al (1994) showed that apical dominance of wild oat (Avena fatua L.) inhibited translocation of imazamethabenz to crown buds. Quackgrass [Elytrigia repens (L.) Nevski] was also more difficult to control when greater numbers of crown buds were present (Alcantara et al 1989), and older buds received less translocated herbicide than younger buds (Shieh et al 1993). All herbicide treatments reduced OWB aerial reproductive tiller density compared with the control in 2001 (Table 1).…”

Translocation of Glyphosate and Quizalofop and Metabolism of Quizalofop in Quackgrass Biotypes (Elytrigia repens)

“…Results of treatment made at older stages were contra dictory: Claus and Behrens (5) and Ivany (10) found no difference whereas Wallgren (19) reported a loss of efficacy at the five-to seven-leaf stage compared with the three-to five-leaf stage. With the APP and CHD herbicides, treatments made at the six-to eight-leaf stage of quackgrass resulted in less control compared with treatment on younger plants (1,4,11,15).…”

Basis for the Differential Response of Quackgrass (Elytrigia repens) Biotypes to Primisulfuron

“…Quack grass biotypes differ in growth and development characteristics. Quackgrass biotypes or clones have exhibited differential re sponses to several herbicides including primisulfuron (1,2,7,8,17). Primisulfuron is a sulfonylurea herbicide registered for postemergence control of quackgrass and other weed species in com (Zea mays L.) at 40 g ha" 1 (3,5,6,9,10,13).…”