Physiological Effects of Late Season Glyphosate Applications on Peanut (<i>Arachis hypogaea</i>) Seed Development and Germination

The development of 2,4-D-resistant cotton and soybean cultivars has created great concern about the potential off-target movement of 2,4-D onto sensitive broadleaf crops. Peanut is often grown in close proximity to cotton and soybean. Therefore, field studies were conducted during 2012 and 2013 at Plains, Ty Ty, and Attapulgus, GA to evaluate peanut response to 2,4-D at 67, 133, 266, 533, and 1066 g ae ha À1 applied at preemergence (PRE), 10, 20, or 30 d after planting (DAP), corresponding to PRE, V2, V3, and V5 peanut growth stages. Nontreated controls (NTC) were included for comparison. Treatment timing by rate interactions were significant (P , 0.0001). As 2,4-D rate increased peanut injury increased. There was variation in yield loss response dependent on peanut growth stage at application timing. Peanut that was treated preemergence and at the V2 growth stage did not have yield loss at any of the 2,4-D evaluated rates (67 to 1066 g ha À1 ) relative to the NTC. When peanut was treated at V3 and V5 growth stages with 2,4-D, injury estimates were 5 to 32% from the 67 to 1066 g ha À1 rates respectively, and peanut canopy diameter was stunted 5 to 35% at the same rates. The resulting peanut yield loss was 23 and 36% from 533 and 1066 g ha À1 of 2,4-D applied at V3 and V5 growth stages; in part due to reproductive growth being initiated during that time-frame and peanut had less time to recuperate before harvest. Linear regression models were used to evaluate peanut injury and peanut yield results. Significant correlations were established for V3 and V5 treatments between injury and yield, injury and canopy diameter, and canopy diameter and yield (P , 0.0001), with correlation coefficients of À 0.48, À 0.76, and 0.51, respectively. Growers and extension agents will be able to use these peanut injury estimates and canopy diameter data to make improved predictions of potential peanut yield loss where off-target movement of 2,4-D or sprayer contamination has occurred.

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confidence: 99%

The Effect of 2,4-Dichlorophenoxyacetic Acid (2,4-D) on Peanut when Applied During Vegetative Growth Stages

Blanchett¹,

Grey

Prostko³

et al. 2017

“…Research has indicated that peanut injury from glyphosate at 240, 320, and 470 g ai ha 21 caused significant yield reduction of 12 to 36% when applications were made 75, 90, and 105 days after planting (DAP) (Grey and Prostko, 2010). In another study, glyphosate applied to peanut at 560 g ai ha…”

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confidence: 99%

“…Peanut is commonly grown in the proximity of cotton and soybean across the southeast (Lassiter et al, 2007;Prostko et al, 2011;Prostko et al, 2013). Herbicide resistance technology is used in most cotton and soybean cultivars for weed management solutions, and the increased use of glyphosate and glufosinate herbicides throughout the growing season increased the occurrence of accidental injury to sensitive crops like peanut (Grey and Prostko, 2010;Johnson et al, 2012a;Lassiter et al, 2007). Peanut foliage injury can occur from herbicide residue remaining in the spray system when it is not properly cleaned prior to the next application in peanut (Grey and Prostko, 2010;Prostko et al, 2011).…”

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confidence: 99%

“…Herbicide drift occurs when the herbicide becomes suspended in air, never reaching the target site, then moving onto a sensitive species nearby (Auch and Arnold, 1978;Grey and Prostko, 2010). Herbicide drift can be linked to many different factors: nozzle type, boom height, wind speed, pressure, spray formulation, sprayer speed, volume per area, and other environmental variables (Wolf et al, 1993).…”

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confidence: 99%

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The Effect of Dicamba on Peanut When Applied during Vegetative Growth Stages

Blanchett¹,

Grey

Prostko³

et al. 2015

The development of dicamba-resistant cotton and soybean cultivars has created great concern about the potential off-target movement of dicamba onto sensitive species, including broadleaf crops. Peanut is often grown in close proximity to cotton and soybean. Therefore, field studies were conducted during 2012 and 2013 at Plains, Ty Ty, and Attapulgus, GA to evaluate peanut response to rates of dicamba (35, 70, 140, 280, and 560 g ae ha 21 ) applied at preemergence (PRE), 10, 20, or 30 d after planting (DAP) corresponding to PRE, V2, V3, and V5 peanut growth stages, respectively. Nontreated controls were included for comparison. As dicamba rate increased, both peanut injury and peanut yield loss increased. Peanut response to dicamba was fit to log-logistic regression models for injury and linear regression models for yield loss. Peanut injury increased with rate of dicamba, but was variable among the locations. A general trend was that peanut plants became more sensitive to dicamba injury as plants approached reproductive stage, as evidenced through a declining linear relationship between I 50 values (i.e. rate of dicamba that elicits a 50% crop response) and timing of application. PRE applications of dicamba had I 50 values that ranged from 125 to 323 g ha 21 of dicamba, while I 50 values were 44 to 48 g ha 21 of dicamba at the V5 peanut growth stage. There was a linear relationship between peanut yield and dicamba rate, with 560 g ha 21 causing maximum yield losses ranging from 0 to 86% when applied PRE, 24 to 82% when applied at V2 growth stage, 30 to 95% when applied at V3 growth stage, and 45 to 88% when applied at V5 growth stage. Across all treatments and locations, there was also a negative linear relationship between peanut yield and peanut crop injury, with a decline of 8.5% yield for every 10% increase in crop injury. Growers and their consultants/extension agents can use this peanut injury data to predict potential peanut yield loss from sprayer contamination or off-target movement of dicamba.

“…When glyphosate was applied to peanut plants at 28 days after planting (DAP), rates of 280 g/ha or higher caused significant yield reductions (Lassiter et al 2007). When applied between 75 to 105 DAP, glyphosate at 240, 320, and 470 g/ha reduced peanut yield by 12%, 24%, and 36%, respectively (Grey and Prostko 2010). Estimated peanut yield losses for dicamba applied at rates between 40 to 560 g/ha at 30, 60, or 90 DAP ranged between 2 and 100% (Prostko et al 2011).…”

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confidence: 99%

Glufosinate Application Timing and Rate Affect Peanut Yield

Prostko

Webster²,

Marshall

et al. 2013

Field studies were conducted at 13 locations across the US peanut belt during 2010-2012 to evaluate peanut response to postemergence applications of glufosinate. Glufosinate was applied at 0, 41, 82, 164, 328 and 656 g ai/ha 30, 60, and 90 days after planting (DAP). There was a significant interaction for peanut yield between application time and glufosinate rate; peanut yield data were regressed on rate of glufosinate and fit to a log-logistic dose response curve by application timing. At 30 DAP, peanut yield ranged from 16 to 92% of the non-treated control, with glufosinate at 266 g/ha causing an estimated 50% reduction in yield (Y 50 ). At 60 DAP, peanut yield ranged from 16 to 82% of the nontreated control, with Y 50 5 266 g/ha of glufosinate. Peanut yield when glufosinate was applied at 90 DAP ranged from 20 to 78% of the non-treated control; Y 50 5 187 g/ha of glufosinate, which was lower than that at 30 DAP and indicated greater peanut sensitivity. Peanut plants treated at 30 DAP had more time to recover from glufosinate injury at the lower rates and/or were in a less susceptible stage of growth relative to 90 DAP. These data provide peanut growers across the US with an estimate of potential yield losses associated with mis-application, off-target movement, or sprayer contamination of glufosinate.