Herbicides were evaluated for weed control and crop response in conventional and no-tillage dry pea production. Preplant or preemergence (PRE) applications of imazethapyr, sulfentrazone, flumetsulam, cloransulam, and BAY FOE 5043 metribuzin did not show crop injury within the locations, years, and tillage systems where applied. Postemergence applications of cloransulam had crop injury in excess of 60% where applied, and injury with flumiclorac and fomesafen ranged from 0 to greater than 40% with differences in crop injury as a result of dry pea growth stage at the time of application and surfactant use. Imazamox injury was as great as 24% when applied at a more advanced dry pea growth stage and was not different from 0% when applied at an earlier growth stage. Dry pea injury with bentazon was not significant, with an exception at one of the six locations where injury was 14%. Common lambsquarters was best controlled (80 to 90%) with sulfentrazone and imazamox. Preplant and PRE applications of sulfentrazone consistently provided the greatest mayweed chamomile control across tillage systems (control ranged from 59 to 93%), whereas bentazon provided the greatest postemergence (POST) control of mayweed chamomile (control ranged from 46 to 84%). Prickly lettuce control with preplant or PRE treatments was greatest with sulfentrazone (74 to 85%), whereas the greatest POST control was with imazamox in combination with urea-ammonium nitrate solution and surfactant or bentazon and crop oil concentrate (71 to 92%). Dry pea yields with herbicide treatments were not always greater than the nontreated and were often affected by crop injury.
Nomenclature: BAY FOE 5043, N-(4fluorophenyl)-N-(1-methylethyl)-2-[[5-(trifluoromethyl)-1,3,4-thiadiazol-2-yl]oxy]acetamide; bentazon; cloransulam; flumetsulam; flumiclorac; fomesafen; imazamox; imazethapyr; metribuzin; sulfentrazone; common lambsquarters, Chenopodium album L. #3 CHEAL; dry pea, Pisum sativum L., ‘Columbia’, ‘Phantom’; mayweed chamomile, Anthemis cotula L. # ANTCO; prickly lettuce, Lactuca serriola L. # LACSE.
Additional index words: Conservation tillage, herbicide efficacy, pea yield.
Abbreviations: COC, Crop Oil Concentrate; DAT, days after treatment; FPP, fall preplant; NIS, nonionic surfactant; POST, postemergence; PPI, preplant incorporated; PRE, preemergence; SPP, spring preplant; UAN, urea-ammonium nitrate solution.
