Effect of cereal rye and canola on winter and summer annual weed emergence in corn

Abstract

Utilization of cover crops has increased rapidly in the United States. However, more information is needed on the proper cover crop termination timing to maximize weed control and crop yield. Field experiments were conducted in 2017 and 2018 at two locations in Indiana to evaluate the influence of cover crop species, termination timing, and herbicide treatment on winter and summer annual weed suppression and corn yield. Cereal rye and canola cover crops were terminated early or late (2 weeks before or after corn planting) with a glyphosate- or glufosinate-based herbicide program. Canola and cereal rye reduced total weed biomass collected at termination by up to 74% and 91%, in comparison to fallow, respectively. Canola reduced horseweed density by up to 56% at termination and 57% at POST application compared to fallow. Cereal rye reduced horseweed density by up to 59% at termination and 87% at POST application compared to fallow. Canola did not reduce giant ragweed density at termination in comparison to fallow. Cereal rye reduced giant ragweed density by up to 66% at termination and 62% at POST application. In general, termination timing had little to no effect on weed biomass and density reduction in comparison to the effect of cover crop species. Cereal rye reduced corn grain yield at both locations in comparison to fallow, especially for the late termination timing. Corn grain yield reduction up to 49% (4,770 kg ha-1) was recorded for cereal rye terminated late in comparison to fallow terminated late. Canola did not reduce corn grain yield in comparison to fallow within termination timing; however, late terminated canola reduced corn grain yield by up to 21% (2,980 kg ha-1) in comparison to early terminated fallow. Results from this study suggest that cereal rye planted at 90 kg ha-1 or canola planted at 6 kg ha-1 can be effective as cover crops for horseweed suppression prior to corn. Cereal rye can also effectively suppress giant ragweed emergence, while canola is not as effective at suppressing large-seeded broadleaves such as giant ragweed. Corn yield loss will likely occur with the use of cereal rye as a cover crop when no supplemental N fertilizers are applied preplant. These results also indicate that early-terminated cover crops can often result in higher corn grain yields than late-terminated cover crops in an integrated weed management program.

Emergence pattern of horseweed (Erigeron canadensis L.) accessions across Nebraska

“…Alternatively, cover crops are considered as one of the most compatible nonchemical horseweed management strategies in no-till corn-soybean rotations. Fall cover crops can reduce horseweed density and the evolution of herbicide-resistant biotypes (DeSimini et al 2020;Wallace et al 2019;Werle et al 2017). Although most seedlings emerged in the fall, management of spring cohorts should not be neglected, as horseweed is a prolific seed producer, and continuous development of fall horseweed management strategies may increase the selection pressure on spring-emerging biotypes, as has been observed in other states.…”

Weed Biology and Ecology Studies: Diversity, Dominance, Population and Weed Growth and Land Use Efficiency in Intercropping Corn (Zea mays l.) with Leguminous Crops in Dryland

“…Broadleaf weeds were more dominant than poaceae and sedges in the monocrop treatment and intercropping of corn with soybeans, green beans and red beans. The reason is because the canopy of soybeans, green beans and red beans is ineffective at intercepting sunlight that passes through the corn canopy (Stephanie et al, 2020). As a result, the weed seed bank in the soil from the previous season is lifted upwards during soil processing and germinates when it gets enough water and sunlight.…”

“…Legume biomass also increases varying soil porosity, due to increased levels of organic matter and increased activity of microorganisms such as phosphorus solubilizing bacteria and Rhizobium (Chieppa et al, 2020). Increased soil porosity in response to the influx of organic matter from weathering groundnut and cowpea leaves makes for a healthier plant growing environment, which will ultimately support better corn growth (Stephanie et al, 2020). Corn, peanuts and cowpeas with ideal growth performance effectively suppress the growth and population of weeds from both the poaceae, sedge and broadleaf groups.…”