Vol. 51â1997 - NorthEastern Weed Science Society
Vol. 51â1997 - NorthEastern Weed Science Society
Vol. 51â1997 - NorthEastern Weed Science Society
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59<br />
HERBICIDE TRATEGIES FOR CONTROL OF ACETOLACTATE SYNTHASE (ALS)<br />
RE 1STANT SMOOTH PIGWEED (AMARANTHUS HYBRIDUS L. )<br />
M. A ISAACS, R. P. WILSON, and B. MANLEyl<br />
ABSTRACT<br />
riments were conducted in 1994 and 1996 at Marion, MD to evaluate selected<br />
erbicide programs for control of ALS-resistant smooth pigweed in soybeans<br />
(Glycinemax L. err), PRE treatments included pendimethalin (prowl, 1.0 lb ai/A), Prowl (0.25<br />
lb ailA) in comb nation with pendimethalin plus imazaquin (Squadron, 0.8741b ai/A), Prowl<br />
(0.25 lb ai/A) pl s Squadron (0.874Ib ai/A) plus metribuzin (Sencor, 0.251b ailA), dimethenamid<br />
(Frontier, 0.9381b ailA) in combination with imazaquin plus dimethenamid (Detail, 0.1251b ai/A),<br />
alachlor (Lasso T, 2.5 lb ai/A), metolachlor (Dual, 1.5 lb ai/A) in combination with linuron plus<br />
chlorimuron ( mini, 0.45 lb ai/A) in 1994, Dual (1.5 Ib ai/A) in combination with metribuzin<br />
plus chlorimuro (Canopy, 0.188 lb ai/A) in 1996, and flumetsulam plus metolachlor (Broadstrike<br />
+ Dual, 2.161b . A). POST treatments were bentazon plus acifluorfen (Storm, 0.75 lb ailA),<br />
lactofen (Cobra, 0.063 lb ailA), imazethapyr (pursuit, 0.063 lb ailA), Pursuit (0.063 lb ai/A) plus<br />
Cobra (0.063 lb ai/A), Pursuit (0.063 lb ailA) plus acifluorfen (Blazer, 0.25 lb ai/A), Pursuit<br />
(0.063 lb ai/A) Ius flumiclorac (Resource, 0.0261b aiJA), and Blazer (0.25Ib ai/A) plus CGA<br />
248757(Action, 0.0026 lb ailA) with COC (1.0 % v/v) or NIS (0.25 % v/v) plus 30 % VAN (1.0<br />
% v/v).<br />
The exp rimental design was a randomized complete block with four replications. Plots<br />
were 10 feet wi e (drilled) by 20 feet long, and treatments were applied with a CO 2 backpack<br />
sprayer deliveri g a spray volume of25 gpa at 30 psi. Data collected consisted of crop injury<br />
and pigweed co trol, Precipitation for 1994 (drought) and 1995 (above average) was<br />
significantly di rent, which lead to dramatic differences in herbicide efficacy over the two years.<br />
In 1994, PRE applications of Prowl provided an average of22 % control of smooth<br />
pigweed three eeks after treatment (WAT). Gemini plus Dual was the most effective treatment,<br />
providing 68 % control. POST applications of Storm, Pursuit plus Blazer, and Blazer plus<br />
Action provide good control of smooth pigweed (> 85 %). In 1995, PRE applications of Prowl<br />
were more eff ive compared to 1994, yet still provided poor control. Lasso MT and Dual plus<br />
Canopy provid d good pigweed control (>80 %), while control with Frontier plus Detail was<br />
poor (53 %). T e addition of Sencor to Prowl plus Squadron greatly enhanced pigweed control<br />
(> 94 %) comp red to Prowl plus Squadron alone (20 %) three WAT. POST applications of<br />
Cobra, Pursuit Ius Cobra, Pursuit plus Blazer, Pursuit plus Resource, and Storm provided good<br />
control of smo th pigweed. Early crop injury was noted with Cobra applications, yet minimal<br />
late in the seas n,<br />
1Grad.<br />
Inst. and State<br />
es. Asst., Prof., Eastern Shore Agric. Res. and Ext. Center, Virginia Polytech.<br />
niv., Painter, VA 23420; Tech. Service Rep., Ciba, Hilliard, OR.
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