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ARS Home » Southeast Area » Tifton, Georgia » Crop Protection and Management Research » Research » Publications at this Location » Publication #190462
Title: TEXAS PANICUM (PANICUM TEXANUM) INTERFERENCE IN PEANUT (ARACHIS HYPOGAEA) AND IMPLICATIONS FOR TREATMENT DECISIONS

Author
item Johnson, Wiley - Carroll
item MULLINIX, JR., BENJAMIN - UNIVERSITY OF GEORGIA

Submitted to: Peanut Science
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 2/28/2006
Publication Date: 2/16/2007
Citation: Johnson, W.C., Mullinix, Jr., B. 2005. Texas panicum (Panicum texanum) interference in peanut (Arachis hypogaea) and implications for treatment decisions. Peanut Science. 32:68-72.

Interpretive Summary: Texas panicum is one of the most common and troublesome weeds of peanut in the southeastern U. S. Successful control of Texas panicum is costly. With reduced profit potential in peanut production there is a need to quantify the competitiveness of Texas panicum and determine when control is justified. Trials were conducted from 2001 through 2003 in Georgia to quantify the effects of Texas panicum interference on peanut and determine the economic threshold. 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 by 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 reduced peanut yields by 52 kg/ha. Twenty weeks of Texas panicum interference reduced peanut yields by 9% compared to controlling Texas panicum 2 weeks after emergence. Based on these data and the cost of Texas panicum control, the minimum density of Texas panicum to justify control is 4.4 plants/20 m row.

Technical Abstract: Trials were conducted from 2001 through 2003 in Georgia to quantify the effects of 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 reduced peanut yields by 52 kg/ha. Twenty weeks of Texas panicum interference reduced peanut yields by 9% compared to controlling Texas panicum 2 weeks after emergence. These data show the importance of effective Texas panicum control and the need to control Texas panicum early in the growing season.