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

Abstract

Greenhouse and field experiments were conducted in North Dakota to determine the effect of adjuvants applied with imazapic on the control of leafy spurge and production of various grass species and to determine the most effective fall-application timing of imazapic for optimum leafy spurge control with minimal effect on herbage. Imazapic applied with a methylated seed oil (MSO) adjuvant tended to provide greater leafy spurge control than when applied with other types of adjuvants. Imazapic applied alone or with adjuvants reduced production of some grass species in the greenhouse, but it did not decrease herbage production in the field. Imazapic at 140 g/ha applied with MSO or with 28% N plus MSO averaged 72% leafy spurge control 12 mo after treatment, compared to 33% control from imazapic alone and 40% control from picloram plus 2,4-D. Imazapic at 140 g/ha applied with MSO in mid-September provided greater leafy spurge control compared to August or October applications.

Reducing Euphorbia esula with a combination of sheep grazing and imazapic

“…In experiment two, however, the imazapic application did reduce overall plant biomass as the grass and forb components had not developed enough to replace E. esula biomass lost after the herbicide application. Others have measured similar plant responses in E. esula infested pastures to imazapic (Markle and Lym, 2001) and to grazing (Olson and Wallander, 1998).…”

“…E. esula, which cattle will not graze, can reduce herbage production over 75% (Lym and Kirby, 1987). Herbicides are effective for E. esula management (Markle and Lym, 2001), but they are expensive and only cost effective when the infestation is dense and the pasture is productive (Lym and Kirby, 1987;Messersmith, 1990;Lym and Messersmith, 1994). Several insect biocontrol agents have been introduced to reduce E. esula infestations (Anderson et al, 2000) with varying levels of success.…”

“…Imazapic should be applied in the autumn for maximum efficacy (Markle and Lym, 2001). Thus the application will occur after the plant has produced and shed seed.…”

Downy Brome (Bromus tectorum) Response to Imazamox Rate and Application Timing in Herbicide-Resistant Winter Wheat

“…Markle and Lym (2001) found that MSO outperformed other adjuvants when applied with imazapic for control of leafy spurge (Euphorbia esula L.). However, Grichar and Sestak (2000) did not find a benefit of using any type of adjuvant in conjunction with imazapic applications for controlling yellow nutsedge (Cyperus esculentus L.) or purple nutsedge (Cyperus rotundus L.).…”

Hierarchical Bayesian methods estimate invasive weed impacts at pertinent spatial scales

“…The other experiments, which we meta-analyzed to derive b w estimates, were conducted by others for the purpose of testing leafy spurge herbicides (Maxwell 1984;Gylling and Arnold 1985;Lym andMessersmith 1985, 1994;Lym 2000;Markle and Lym 2001). Whereas the removal experiment data were helpful for testing the model, potential problems with the experiments dissuaded us from relying on them for model development.…”