Dose response of weeds to methyl iodide and methyl bromide

Abstract

Summary Labonuory bioassay and field experiments were conducted to characterize the dose response of weeds to methyl iodide and methyl bromide as soil fumigants. The patterns in potency of both fumigants and in sensitivity of diffcretit weed species to the fumigants were distinguished with the use of logistic dose‐response models. Similar to its response to methyl hromide fumigation. Amaranthus retrofleus L. was the most sensitive to methyl iodide fumigation. Cyperus rotundtis L. was the least sensitive to methyl iodide fumigation, whereas Portuloca oleracea L. was the least sensitive to methyl hromide. Lolium multiflorum Lam. Abutilon theophrasti Medik.Chenopodium album L. P. ateracea. Brassica kaber (D.C.) L.C. Wheeler and Cyperus escuden‐tus L. were similar in sensitivity to methyl iodide. Methyl iodide was as potent as methyl bromide for A. retroflexus but more potent than methyl bromide for L. multiflorum, A. theophrasti. C. album. P. oleracea. B. kaber, C. esculentus and C. rotundus. The dose response for weeds in the field was similar to that obtained in laboratory bioassays. Under fieid conditions. 280 kg ha‐1 methyl iodide killed all species tested except Solanum nigrum L Methyl iodide appears to be a suitable replacement for meihyl bromide because it can be used in situations simitar to methyl bromide fumigation, has superior efficacy against a broad spectrum of pests and has a low potential for degrading the earth's ozone lavers.

The biology of Canadian weeds. 130. Amaranthus retroflexus L., A. powellii S. Watson and A. hybridus L.

“…Herbicide labels generally do not distinguish among the three species, and most refer only to redroot pigweed. The soil fumigants methyl iodide and methyl bromide have been reported to be effective at controlling populations of A. retroflexus (Zhang et al 1997).…”

The biology of Canadian weeds. 8. Sinapis arvensis. L. (updated)

“…Donald and Tanaka (1993) also found that annual application of AC94377 at 3.4 kg ha -1 in a field trial in North Dakota reduced seed survival of shallowly buried (1.25 cm deep) wild mustard by 80% after 3 yr. Zhang et al (1997) compared the dose response of eight weed species to two soil fumigants in the laboratory and field and found that methyl iodide was 50% more potent than methyl bromide for inhibiting germination of S. arvensis.…”

The Effect of Sugar Beet Broadleaf Herbicides on Fluorescence Induction Curves in Amaranthus retroflexus L. and Portulaca oleracea L.

“…Between species, the effects of applied herbicides were severe on P. oleracea control than A. retroflexus. Zhang et al (1997) demonstrated that photosynthetic inhibitors such as bentazon had an excellent performance on P. oleracea control. Fennimore and Rachuy (2005) reported that desmedipham/ phenmedipham and ethofumesate applications provided acceptable control of P. oleracea and A. retroflexus.…”

“…Zhang et al (1997) reported that P. oleracea was resistant to PGR herbicides like 2,4-D and was tolerant to ALS inhibitor herbicides like imazethapyr. In contrast, clopyralid affected A. retroflexus at the same dosage (Fig.…”