Texas Panicum (Panicum texanum) Interference in Peanut (Arachis hypogaea) and Implications for Treatment Decisions

Abstract

Trials were conducted from 2001 through 2003 in Georgia to quantify Texas panicum interference on peanut. One set of trials investigated the effect of Texas panicum densities on peanut yield, grade, and harvest losses. Natural infestations of Texas panicum were thinned to densities of 0, 1, 2, 4, 8, 16, and 32 plants/20 m row, two weeks after peanut emergence. Other trials evaluated the duration of Texas panicum interference from a density of 8 plants/20 m row and effect of subsequent removal on peanut yield. Texas panicum interference was allowed for 2, 4, 6, 8, 10, 12, 14, 16, 18, and 20 weeks after peanut emergence, in addition to a season-long weed-free control. Texas panicum plants were removed at the desired times with spot applications of clethodim. Peanut yield was reduced at a linear rate by increasing Texas panicum density, with each plant/20 m row reducing peanut yields by 25 kg/ha. At densities of 40 plants/20 m row, Texas panicum was predicted to reduce peanut yields 25%. Texas panicum densities did not affect peanut grade. Harvest losses increased at a linear rate as Texas panicum densities increased. Every week of Texas panicum interference from a density of 8 plants/20 m row reduced peanut yields by 20 kg/ha. Twenty weeks of Texas panicum interference reduced peanut yields by 7% compared to controlling Texas panicum season-long. These data show the importance of effective Texas panicum control and the need to control Texas panicum early in the growing season.

Competing with the competitors in an endless competition: a systematic review of nonchemical weed management research in peanut (Arachis hypogea) in the United States

“…dichotomum ] (1%), while weed research on sedges has mainly focused on yellow nutsedge ( Cyperus esculentus L.) (19%). Although annual grasses are very competitive, they are not considered a major problem in peanut high-input systems because of the availability of residual herbicides, such as flumioxazin, pendimethalin, and S -metolachlor, and postemergence herbicides, such as clethodim, fluazifop- P -butyl, and sethoxydim, that can provide effective control of these weed species (Burke et al 2004; Johnson and Mullinix 2005). This may justify the lower research attention for grasses compared with broadleaf weeds in peanut.…”

“…Season-long interference of grass weed species was reported to reduce peanut yield by 7% to greater than 60% (Everman et al 2008b; York and Coble 1977). As few as 1.4 U. platyphylla plants m −2 (Chamblee et al 1982), 0.1 D. dichotomum plants m −2 (York and Coble 1977), and 2.2 U. texana plants m −2 (Johnson and Mullinix 2005) reduced peanut yield by 25%. In contrast, greater densities of C. esculentus (68 plants m −2 ) and broadleaf weeds ( D. tortuosum : 6.2 plants m −2 ; horsenettle [ Solanum carolinense L.]: 4.2 plants m −2 ; and S. obtusifolia : 7.2 plants m −2 ) were required to cause similar yield reduction in peanut (Hackett et al 1987; Johnson and Mullinix 2003).…”

“…Although these weed interference studies were conducted using different peanut cultivars under different growth conditions and cultural practices, the values for yield reduction are similar among grass weed species, which is not the case for broadleaf weeds (Table 2). Apart from competition for growth resources, grass weed species generally reduce peanut yield through the production of a fibrous root system that entangles peanut pods during digging, resulting in excessive harvest losses (Johnson and Mullinix 2005). For example, Johnson and Mullinix (2005) observed 836 kg ha −1 harvest losses at 2 U. texana plants m −1 of peanut row.…”

“…Apart from competition for growth resources, grass weed species generally reduce peanut yield through the production of a fibrous root system that entangles peanut pods during digging, resulting in excessive harvest losses (Johnson and Mullinix 2005). For example, Johnson and Mullinix (2005) observed 836 kg ha −1 harvest losses at 2 U. texana plants m −1 of peanut row. Greater competition of the grass weed species may also be attributed to their C 4 metabolism, which confers a higher efficiency in water use, nutrient uptake, and net photosynthesis compared with peanut, which has a C 3 pathway of photosynthetic CO 2 fixation (Procopio et al 2004; York and Coble 1977).…”