Imazethapyr for Broadleaf Weed Control in Peanuts (Arachis hypogaea)

Abstract

Abstract Field experiments were conducted at the Tidewater Agric. Exp. Station, Suffolk, VA in 1988 and 1989 to evaluate imazethapyr [(±)-2-[4,5-dihydro-4-methyl-4-(1-methylethyl)-5-oxo-1H-imidazol-2-yl]-5-ethyl-3-pyridine-carboxylic acid]for broadleaf weed control in peanuts (Arachis hypogaea L.). Imazethapyr was applied preplant-incorporated (PPI), preemergence (PRE), at ground-cracking (GC), and postemergence (POT) at rates of 0.036, 0.071, or 0.105 kg ai ha-1. Several sequential imazathapyr systems were also included. The standard of pendimethalin (N-ethylpropyl)-3, 4-dimethyl-2,6-dinitrobenzenamine) PPI, metolachlor(2-chloro-N-(2-ethyl-6-methylphenyl)-N-(2-methoxy-1-methylethyl)acetamide) PRE, and acifluorfen (5-[2-chloro-4-(trifluoromethyl)phenoxy]-2-nitrobenzoic acid) plus bentazon (3-(1-methyethyl)-(1H)-2,1,3-benzothiadiazin-4(3H)-one 2, 2-dioxide) POT was included for comparative purposes. Imazethapyr applied either PPI or PRE at 0.071 or 0.105 kg ha-1 provided <90% spurred anoda (Anoda cristata (L.) Schlecht.), control and <96% prickly sida (Sida spinosa L.), control. Eclipta (Eclipta prostrata L.) control was 95% when imazathapyr was applied PRE at 0.105 kg ha-1. Greater than 90% annual morningglory (Ipomoea spp.) control was only achieved with imazethapyr applied PPI or PRE at 0.105 kg ha-1. The standard provided complete control of eclipta, and 51%, 92%, and 94% control of spurred anoda (Anoda cristata (L.) Schlecht.), prickly sida (Sida spinosa L.), and annual morningglories, respectively. Several imazethapyr systems yielded equivalent to the standard. Averaged across all rates, imazathapyr applied PPI yielded 4110 kg ha-1, PRE = 3860 kg ha-1, GC = 3680 kg ha-1, and POT = 3370 kg ha-1. Several imazethapyr systems provided net returns equivalent to the standard. Corn grown the following year was not injured by any imazethapyr treatment to peanuts the previous year.