Weed management in bromoxynil-resistantGossypium hirsutum

Abstract

An experiment was conducted at two locations in Georgia and two locations in North Carolina during 1994 and 1995 to evaluate weed management in conventional-tillage bromoxynil-resistantGossypium hirsutumL. (cotton). The weed management systems evaluated included different combinations of fluometuron preemergence (PRE), bromoxynil or bromoxynil plus MSMA early postemergence (EPOST), bromoxynil postemergence (POST), and cyanazine plus MSMA late post-directed (LAYBY). Fluometuron PRE improved control ofAcanthospermum hisptdiumDC. (bristly starbur),Cassia occidentalisL. (coffee senna),Chenopodium albumL. (common lambsquarters),Desmodium tortuosum(Sw.) DC. (Florida beggarweed),Sida spinosaL. (prickly sida),Jacquemontia tamnifolia(L.) Griseb. (smallflower morningglory), andAnoda cristata(L.) Schlecht. (spurred anoda), compared to system that did not use fluometuron PRE. It also improvedG. hirsutumyields at three four locations. Bromoxynil-containing systems provided better weed control and higherG. hirsutumyields than systems without bromoxynil. Bromoxynil EPOST controlledA. hispidium, C. occidentalis, C. album, D. tortuosum, S. spinosa, J. tamnifolia, andA. cristata.Control of these species was frequently improved by a second application of bromoxynil POST. Bromoxynil EPOST, POST, or EPOST plus POST did not controlSenna obtusifolia(L.) Irwin and Barneby (sicklepod), but the addition of MSMA to bromoxynil EPOST improvedS. obtusifoliacontrol. Control of all dicotyledonous weeds was improved by a LAYBY treatment of cyanazine plus MSMA, and yields were improved at three of four locations with this treatment.Gossypium hirsutumwas not injured by POST treatments of bromoxynil, and only temporary injury resulted from POST treatments of MSMA.