Peanut Seedling Response to Dinitroaniline Herbicides Applied Preplant Incorporated and Preemergence1

Abstract

Greenhouse studies were conducted in 1995, 1996, and 1998 to measure the effect of preplant incorporated (PPI) and preemergence (PRE) applications of ethalfluralin and pendimethalin on growth of individual peanut seedlings in pots. Herbicide rates evaluated were 0, 0.6, 1.1, and 2.2 kg ai/ha for each herbicide. Parameters measured were time of emergence, seedling height, canopy width, foliage biomass, root length, and root biomass of individual plants. PPI applications were more injurious than PRE applications for all parameters regardless of herbicide. Ethalfluralin PPI inhibited peanut seedling growth more than equivalent rates of pendimethalin PPI. However, peanut seedling responses to PRE applications of ethalfluralin and pendimethalin were generally the same.

Phytotoxicity of Delayed Applications of Dinitroaniline Herbicides in Strip-Tillage Peanut Production

“…When combined across all possible application timings, peanut treated with ethalfluralin had lower yields than those treated with pendimethalin (Table 1). This is not consistent with earlier studies that showed no phytotoxicity from ethalfluralin (Johnson and Mullinix 1999;Johnson et al 1997). Those trials were in conventional tillage peanut production systems, with comparisons between preplant incorporated and PRE applications at increasing rates.…”

“…Peanut yield response to ethalfluralin was not expected. Earlier trials showed peanut to be very tolerant of ethalfluralin applied PPI or PRE at increasing rates (Johnson and Mullinix 1999;Johnson et al 1997). Those trials were in conventional tillage systems and at recommended application timings.…”

Weed Control and Peanut Tolerance with Ethalfluralin-Based Herbicide Systems

“…Peanut tolerance to the dinitroaniline herbicides has been questioned previously [12][13][14]. Greenhouse studies showed that ethalfluralin inhibited seedling growth more than pendimethalin at equivalent rates applied preplant incorporated; however, injury by these herbicides following 2 International Journal of Agronomy preemergence (PRE) applications were similar [15]. In runner peanuts, which are more prone to peg injury compared to Spanish peanut, proper herbicide incorporation was needed to prevent injury.…”

“…In Florida, ethalfluralin did not cause peanut injury at any rate or application timing [12]. Dinitroaniline injury on peanut includes a swollen hypocotyl, abnormal lateral root growth, and stunted plants [15,16].…”

Influence of Application Rate and Timing of Diclosulam on Weed Control in Peanut (Arachis hypogaea L.)

“…The residual herbicides alachlor [2-chloro-N-(2,6-diethylphenyl)-N-(methoxymethyl) acetamide] (Johnson et al, 1993), imazethapyr {2-[4,5-dihydro-4-methylmethyl-4-( 1-methylethyl)-5-oxo-1H-emidazol-2-yl]-5-ethyl-3pyridinecarboxylic acid} (Wilcut et al, 1994Greyet al,l995;Richburget al, 1995b,c;Grichar and Nester, 1997), imazapic {(±)-2-[4,5-dihydro-4-methyl-4-( 1-methylethyl)-5-oxo-lH-imidazol-2-yl]-5-methyl-3-pyridinecarboxylic acid} (Richburg et al, 1995a,c;Wilcut et al, 1995b;Grichar and Nester, 1997;Webster et al, 1997), metolachlor [2-chloro-N-(2-ethyl-6-methylphenyl)-N-(2-methoxy-1-methylethyl)acetiamide] ( Richburgetal., 1995b;Gricharetal., 1996), ethalfluralin [N -ethyl-N -( 2-methyl-2-propenly )-2,6-dintro-4-(trifluoromethylrbenzenamine] and pendimethalin [N-(1-ethylpropyl)-3,4-dimethyl-2,6-dinitrobenzenamine] (Johnson and Mullinix, 1999) often are applied to control or suppress grass and broadleaf weeds and nutsedges. Peanut development and maturity require a relatively long growing season (140-160 d) , and residual activity of herbicides applied at planting may not control weeds throughout the entire season.…”