Low carryover risk of corn and soybean herbicides across soil management practices and environments

Abstract

Herbicides with soil-residual activity have the potential for carryover into subsequent crops, resulting in injury to sensitive crops and limiting productivity if severe. The increased use of soil residual herbicides in the United States for management of troublesome weeds in corn and soybean cropping systems has potential to result in more cases of carryover. Soil management practices have different effects on the soil environment, potentially influencing herbicide degradation and likelihood of carryover. Field experiments were conducted at three sites in 2019 and 2020 to determine the effects of corn (clopyralid and mesotrione) and soybean (fomesafen and imazethapyr) herbicides applied in the fall at reduced rates (25% and 50% of labeled rates) and three soil management practices (tillage, no-tillage, and a fall established cereal rye cover crop) on subsequent growth and productivity of the cereal rye cover crop and the soybean and corn crops, respectively. Most response variables (cereal rye biomass and crop canopy cover at cover crop termination in the spring, early season crop stand, and herbicide injury ratings, and crop yield) were not affected by herbicide carryover. Corn yield was lower when soil was managed with a cereal rye cover crop compared to tillage at all three sites while yield was lower for no-till compared to tillage at two sites. Soybean yield was lower when managed with a cereal rye cover crop compared to tillage and no-till at one site. Findings from this research indicate a low carryover risk for these herbicides across site-years when label rotational restrictions are followed and environmental conditions favorable for herbicide degradation exist, regardless of soil management practice on silt loam or silty clay loam soil types in the Midwest U.S. region.

Shortening critical period of weed control at soybean by residual herbicide mixtures

“…or decrease its permanence in each environment (Grint et al, 2022). Different levels of phytotoxicity in soybean caused by the use of pre-emergent herbicides at the time of sowing are found in the literature, ranging from 12.0% by the application of sulfentrazone + diuron (Galon et al, 2022), reduction of soybean canopy area by 1.5% by the application of sulfentrazone (Arsenijevic et al, 2021) and an eleven-day delay in canopy closure with application of flumioxazin + metribuzin + pyroxasulfone when compared to treatment without pre-emergence herbicide (Arsenijevic et al, 2022).…”

Evaluating the effects of manual hoeing and selective herbicides on maize (Zea mays L.) productivity and profitability

“…On the other hand, repeated applications of an herbicide at a non-standard dose and the antagonism between the different active ingredients in the mixture can favor the emergence of ‘‘super weeds'’ weeds that are very difficult to control [ 83 ]. In crop rotations, herbicides that persist for a long period in the soil can induce phytotoxicity to the next crops [ 84 ], the plant's poor ability to eliminate herbicide residues from its metabolism may favor their storage in various organs such as fruits, stems, leaves, tubers or seeds, with the risk of contamination of the food chain [ 85 ].…”

Preemergence herbicide premixes reduce the risk of soil residual weed control failure in corn

“…An effective strategy to minimize the overreliance on POST herbicide applications is to apply soil residual preemergence (PRE) herbicides for early season weed control (Knezevic et al 2019). The use of herbicides with effective soil residual activity applied PRE provides an extended period of early season weed control, protecting crop yields during their most vulnerable developmental stages from weed interference (Grint et al 2022b; Oliveira et al 2017a). PRE herbicides can reduce the weed density and delay the time to POST applications, thus lowering the selection pressure for further resistance to POST herbicides (Faleco et al 2022a; Oliveira et al 2017b).…”