Sensitivity and Likelihood of Residual Herbicide Carryover to Cover Crops

Abstract

Research was conducted to evaluate the sensitivity of cover crops to a low rate of soil-applied herbicides and investigate the likelihood of herbicide carryover to fall-seeded cover crops following an irrigated corn crop. In the sensitivity study, herbicides were applied at a 1/16×rate (to simulate four half-lives) 1 d after cover crop planting, whereas for the carryover study residual herbicides were applied at a 2×rate at the maximum label corn height or growth stage and cover crops sown immediately after corn harvest. In the sensitivity experiment, atrazine, diuron, fluridone, fomesafen, metribuzin, pyrithiobac, and sulfentrazone reduced emergence of the leguminous cover crops Austrian winterpea, crimson clover, and hairy vetch. However, reduced biomass production of leguminous cover crops in the spring was only observed for atrazine, fluridone, and pyrithiobac. For rapeseed, atrazine, flumioxazin, fluridone, pyrithiobac, pyroxasulfone, sulfentrazone, and tembotrione reduced emergence, but biomass production was reduced only by atrazine and fluridone. Conversely, wheat, cereal rye, barley, oats, and triticale were not affected by soil-applied herbicides. Barley was the only cereal cover crop that showed biomass reduction due to the application of flumioxazin, fluridone, mesotrione,S-metalochlor, and sulfentrazone. In the carryover study, with the exception of crimson clover, Austrian winterpea, cereal rye, hairy vetch, rapeseed, and wheat showed no negative affect on biomass production following a 2×rate of postemergence-applied residual herbicide in corn.

Herbicide carryover to various fall-planted cover crop species

“…Cornelius and Bradley (2017) reported biomass reductions from herbicide carryover onto wheat, forage radish, cereal rye, crimson clover, oats, Austrian winter pea, annual ryegrass, and hairy vetch. Palhano et al (2018) observed results similar to what we found, with no biomass reduction of Austrian winter pea, cereal rye, wheat, hairy vetch, or rapeseed, but they did observe a biomass reduction of crimson clover from atrazine, pendimethalin, pyroxasulfone, and S-metolachlor. Differences between our findings and the results from this previous research are most likely due to differences in the environmental and soil conditions in Virginia compared with those of Arkansas and Missouri.…”

“…Treatments containing imazethapyr, fomesafen, and flumetsulam resulted in the greatest herbicide carryover symptoms across all cover crop species evaluated (Cornelius and Bradley 2017). In Arkansas, Palhano et al (2018) observed carryover injury on crimson clover from atrazine, pendimethalin, pyroxasulfone, and S-metolachlor, and on cereal rye and wheat from pyroxasulfone. Other research indicates that atrazine and metsulfuron injured wheat a year after it was applied (Moyer et al 2010).…”

“…Herbicides applied during the cash crop growing season have the potential to persist in the soil and injure cover crops (Cornelius and Bradley 2017;Palhano et al 2018). Because of the complex interactions and variation in herbicide degradation among climate and soil conditions, research is needed to corroborate previous studies and evaluate herbicide carryover potential to reduce establishment of cover crops commonly used in the mid-Atlantic region of the United States.…”

Atrazine nanoencapsulation improves pre‐emergence herbicidal activity against Bidens pilosa without enhancing long‐term residual effect on Glycine max

“…20,22 Another concern regarding atrazine application is the residual effect of the herbicide in susceptible succession crops. 23 For example, maize and soybean rotation is a common practice in several regions around the world, 24 and atrazine applied for weed control during maize cultivation has been shown to negatively affect the subsequent development of soybean plants in the same area. 25 It is therefore of great relevance to evaluate how atrazine nanoencapsulation would affect the residual herbicidal effect on a susceptible crop.…”

Use of Sunflower and Soybean as Bioindicators to Detect Atrazine Residues in Soils

“…Numerous studies have shown the sensitivity of crops to the carryover effect of atrazine, which significantly reduces vetch, clover and bean biomass, and minimizes the emergence of barley and oats by 20% and 16%, respectively (Palhano et al, 2018). Sunflower (Helianthus annuus L.) is also sensitive when sown shortly after application of atrazine to the predecessor crop (Brighenti et al, 2002).…”