Efficacy of integrated weed management in peanut production utilizing high cover crop residue

Authors: PRICE, KATILYN - Auburn University; LI, STEVE - Auburn University; LANGEMEIER, RYAN - Auburn University; NAGILA, ASMITA - Auburn University; Price, Andrew

Submitted to: Proceedings of Southern Weed Science Society
Publication Type: Abstract Only
Publication Acceptance Date: 1/26/2021
Publication Date: 1/26/2021
Citation: Price, K., Li, S., Langemeier, R., Nagila, A., Price, A.J. 2021. Efficacy of integrated weed management in peanut production utilizing high cover crop residue [abstract]. Proceedings of Southern Weed Science Society.

Interpretive Summary: As herbicide-resistant weeds continue to emerge and spread, alternative non-chemical control methods integrated into current control programs need to be evaluated. The objectives were to (1) evaluate the effectiveness of residual herbicides on weed control in conventionally tilled versus high cover crop residue systems in peanut production; (2) determine if weed control was greater with the combination of cover crops and residual herbicides compared to herbicide only programs. Field trials were conducted in Henry County in 2019, as well as Henry and Macon County in Alabama in 2020. Treatments included four different herbicides applied at planting and a conventionally tilled non-treated check (NTC), and high residue NTC. Weed population counts were collected every 7 days till 56 days after planting when weed biomass was quantified. All treatments that included a heavy cover residue had significantly better control (>80%) of morningglory species and sicklepod compared to the conventionally tilled NTC over 2019-2020. Palmer amaranth control was more variable from year to year and cover crop residue alone was not enough to provide significantly better control than conventionally tilled plots with residual herbicides. Overall, total weed biomass in plots with residue cover and soil residual herbicides had significantly reduced weed biomass of 75-89% compared to conventionally tilled NTC in 2019-2020. The combination of residual herbicides with a high cover crop residue provided more effective weed control overall compared to the high residue alone suggesting some residual herbicides reached the soil surface.

Technical Abstract: As herbicide-resistant weeds continue to emerge and spread, alternative non-chemical control methods integrated into current control programs need to be evaluated. Few studies have been conducted to determine the effectiveness of residual herbicides sprayed onto cover crop residues compared to conventionally tilled systems in peanut. The objectives were to (1) evaluate the effectiveness of residual herbicides on weed control in conventionally tilled versus high cover crop residue systems in peanut production, (2) determine if weed control was greater with the combination of cover crops and residual herbicides compared to herbicide only programs. Field trials were conducted in Henry County in 2019, as well as Henry and Macon County in Alabama in 2020. Treatments included: acetochlor 1,260, flumioxazin 107, diclosulam 26, S-metolachlor 1,700 g ha-1, conventionally tilled non-treated check (NTC), and high residue NTC. All treatments were applied with a backpack sprayer on the day of planting at 187 L ha-1. Weed population counts were collected every 7 days till 56 days after planting when weed biomass was quantified. All treatments that included a heavy cover residue had significantly better control (>80%) of Ipomoea spp. and Senna obtusfolia compared to the conventionally tilled NTC over 2019-2020. Amaranthus palmeri control was more variable from year to year and cover crop residue alone was not enough to provide significantly better control than conventionally tilled plots with residual herbicides. Overall, total weed biomass in plots with residue cover and soil residual herbicides had significantly reduced weed biomass of 75-89% compared to conventionally tilled NTC in 2019-2020. Combinations of flumioxazin or diclosulam with heavy cover crop residue provided the greatest overall weed control in peanut. Generally, the combination of herbicides and cover crops had greater control than either component used alone. The combination of residual herbicides with a high cover crop residue provided more effective weed control overall compared to the high residue alone suggesting some residual herbicides reached the soil surface.