Effect of Environment and Adjuvants on Asulam Phytotoxicity

Abstract

Experiments were conducted to determine the influence of various factors on asulam {methyl[(4-aminophenyl)sulfonyl] carbamate} toxicity to flax (Linum usitatissimumL.) and wild oats (Avena fatuaL. # AVEFA). Asulam toxicity to both flax and wild oats generally increased as temperature, humidity, and soil moisture increased after treatment. Octoxynol {α-[p-1,1,3,3-tetramethyl butyl phenyl]-ω-hydroxypoly(oxyethylene)} in the spray solution increased asulam toxicity to both species in all environments. Octoxynol and trimethylenonypolyethoxyethanol (WK) enhanced asulam toxicity more than other adjuvants evaluated. Asulam toxicity to both flax and wild oats increased as octoxynol concentration in the spray increased. Flax tolerance to asulam generally increased with flax height at treatment. ‘Flor’ flax was the most asulam susceptible of six cultivars evaluated. A 2-mm simulated rainfall within 3 or 6 h after asulam treatment reduced toxicity to wild oats and flax, respectively.

Influence of Rainfree Period After Asulam Application on Johnsongrass (Sorghum halepense)Control

“…In the second study in 1992 the critical rainfree period was 14 HAT. The level of johnsongrass control observed after the critical rainfree period in the second study was equivalent to that observed and/or taller (3,13). In study 3 in 1993, even though johnsongrass plants were shorter, the rhizome system was i5of-\ \ \ more extensive because the site was a year older, being established at the same time as the 1992 studies.…”

“…Surfactants are commonly used to enhance herbicide activity and to increase leaf absorption (9,10,11,13). Under adverse environmental conditions, enhancement of herbicide absorption increased johnsongrass control (10,11).…”

“…The critical rainfree period can be defined as the period of time required to maximize efficacy from a herbicide application. Some adjuvants shorten the critical rainfree period for several herbicides (4,5,15,19), including asulam (3,13,16).…”

Influence of temperature and light intensity on absorption, translocation, and phytotoxicity of fenoxaprop-ethyl and imazamethabenz-methyl in Avena fatua

“…The influence of temperature on herbicide translocation and phytotoxicity varied (Blair et al 1983, Coupland 1986, Devine et al 1983, Grafstorm and Nalewaja 1988, Kells et al 1984, Klevorn and Wyse 1984, Morrison 1983, Nalewaja and Woznica 1988, Smeda and Putnam 1990, Wills 1984, Wills and McWhorter 1983. There have been limited studies on the effects of light intensity on herbicide performance and underlying physiologic processes.…”

Optimizing Diluent Volume Improves Johnsongrass Control in Sugarcane (Saccharumsp.) with Asulam

“…The amount of asulam available for translocation to the above-and below-ground meristematic regions of rhi zome johnsongrass depends upon the amount of asulam absorbed. Absorption can be limited by factors such as the plant's metabolic activity, insufficient leaf wetting, wash-off of chemical from rainfall, or temperature or moisture stress (3,5,9,13). When absorption is reduced, the absorbed asulam is probably diluted to the point that toxic levels can accumulate only in the most dominant buds of the shoot and rhizome thereby reduc ing the degree and longevity of control.…”