Leafy Spurge (Euphorbia esula) Response to AC 263,222

Abstract

Leafy spurge is an exotic perennial weed that infests more than 1 million ha in North America and reduces rangeland carrying capacity. Experiments were initiated on range sites in Nebraska and North Dakota in 1994 and 1995 to determine the response of leafy spurge and other vegetation to AC 263,222. Herbicide treatments evaluated included AC 263,222 at 0 to 280 g ai/ha, picloram at 560 g ai/ha plus 2,4-D at 1,120 g ae/ha, and quinclorac at 1,120 g ai/ha. In Nebraska, a single application of AC 263,222 in the fall at 140 g/ha provided ≥ 90% leafy spurge control 11 to 12 mo after treatment. At Jamestown, ND, leafy spurge control increased to almost 90% and stem density declined to two shoots/m212 mo after the second consecutive fall application of AC 263,222 at 140 g/ha. At Hankinson, ND, leafy spurge control was ≤ 50% when AC 263,222 was applied in the fall only, but increased to > 80% when AC 263,222 was applied in the fall and again at 70 or 140 g/ha in the spring. There were no differences in herbage biomass of established cool- and warm-season grasses where AC 263,222 at 140 g/ha, picloram plus 2,4-D, quinclorac, or no herbicide was applied in the fall. In contrast, application of AC 263,222 in the fall and again in the spring usually reduced cool-season grass biomass.

Observation: Leafy spurge control in western prairie fringed orchid habitat

“…Masters et al (1998) and Markle and Lym (2001) reported similar control of leafy spurge with Imazapic to the present study with little to no loss in herbage production. However, Imazapic has been injurious to grasses when a fall treatment was followed by a spring treatment compared to a single fall treatment (Masters et al 1998).…”

“…The response of leafy spurge and grass to herbicides was similar to previous reports. Kuehl and Lym (1997) and Masters et al (1998) reported good leafy spurge control with fall-applied quinclorac treatments without adverse affects on forage yields. Masters et al (1998) and Markle and Lym (2001) reported similar control of leafy spurge with Imazapic to the present study with little to no loss in herbage production.…”

“…Kuehl and Lym (1997) and Masters et al (1998) reported good leafy spurge control with fall-applied quinclorac treatments without adverse affects on forage yields. Masters et al (1998) and Markle and Lym (2001) reported similar control of leafy spurge with Imazapic to the present study with little to no loss in herbage production. However, Imazapic has been injurious to grasses when a fall treatment was followed by a spring treatment compared to a single fall treatment (Masters et al 1998).…”

“…The western prairie fringed Control Glyphosate + Imazapic 2, 4-D Herbicide treatments orchids had completed their life cycles and were senescent when the herbicides were applied, so little Imazapic and quinchlorac absorption and translocation into the western prairie fringed orchid roots was expected. Also some evidence suggests that quinclorac and Imazapic are more likely to damage dicots such as leafy spurge than they are to damage monocots such as the western prairie fringed orchid , Kuehl and Lym 1997, Masters et al 1998, Markle and Lym 2001. Cover of grasses was reduced by most of the herbicide treatments relative to the control, but grass production 23 months after first treatment in the Imazapic and quinclorac treatments was higher compared to the untreated plots (Table 3).…”

Leafy Spurge (Euphorbia esula) Control and Herbage Production with Imazapic1

“…Grass injury from imazapic at 140 g/ha fall applied may have been less than would be expected from imazapic applied according to label recommendations: 210 g/ha in the fall or 140 g/ha in the fall plus an additional 70 g/ha in the spring. For example, Masters et al (1998) showed that imazapic applied in the fall plus spring reduced grass production compared to a single fall application.…”