Project Overview

Reports

Commodities

• Agronomic: soybeans, wheat

Target Pests

• Target Pests: weeds

Practices

• Pest Management: allelopathy, chemical control, competition, cultural control, mulches - living

The problem or opportunity: The rapid evolution of numerous populations of herbicide-resistant weeds, the dwindling options for chemical control in many production systems, and the mounting evidence that this ‘chemical only’ strategy is insufficient for controlling weeds should be of urgent concern to all stakeholders of weed management (Bagavathiannan and Davis 2018). Even as chemical control options have decreased in many production systems, dependence on herbicides for weed control has steadily increased, creating conditions favorable for reduced economic returns to chemical management and outright weed management failures. This is despite decades of warnings to diversify management tactics in recognition of weeds' prodigious evolutionary capabilities (Baker 1974, Buhler 2002, Norsworthy et al. 2012). Agriculture in the Southern states is currently experiencing the same global predicament. To combat the continued loss of management tools brought on by herbicide-resistant weeds in the southern region, IPM-based solutions that reduce weed emergence and densities through nonchemical means are necessary. IPM-based weed management methods in the area have not yet undergone considerable development, mostly due to a perception that there is no need for them given the efficacy of the available chemical choices as well as widespread belief that new herbicide technology will be able to control herbicide-resistant weeds.

Weeds that can successfully establish in crop fields, which are generally disturbed (mostly through tillage) and characterized as productive sites, maintain their abundance. In annual cropping systems, growers reduce stress to crops through seedbed preparation, fertilization, and irrigation/drainage for successful crop establishment. Resources for plant growth greatly exceed the need of both crop and weeds for several weeks after the crop is planted, and during this period competition has a negligible effect on seedling establishment allowing weeds to prosper and occupy space before resources are monopolized by crops. Herbicide technology advancements over the past 70 years have been tremendously successful in halting the growth of weeds in crop fields and achieving desirable agricultural results. However, weeds have continued to proliferate and suppress crop yields, primarily by evolving resistance to the only means of major selective pressure, herbicides.

The approach: Relay intercropping creates environments that are diametrically opposed to conventional systems and disfavors weeds that have adapted to emerge and prosper in disturbed habitats over time. Considering this, we will examine to what extent wheat-soybean relay intercropping contribute to smother weeds relative to a standard full-season soybean production system. Through field research and multiple outreach efforts, we aim to develop and promote an IPM-based tactic that southern crop growers can implement as a supplementary tool to achieve sustainable weed management goals.

The anticipated outcomes: This project will provide information on level of early weed suppression, seed production, and seedbank dynamics in wheat-soybean intercropping. These data will provide valuable early information to share with stakeholders at meetings and field days to increase awareness about this IPM tool and potentially the more profitable cropping system for the region. Moreover, the stakeholders in the region will be more aware that nonchemical weed management tactics that are practical as well as effective are available to them. The stakeholders will also be aware of the need for sustainable weed management strategies and will have an increased understanding of general IPM strategies that can be implemented in resilient crop production systems. Online accessibility of the research results in text and visual forms will reach broader audiences throughout the Southern region and beyond. This grant funding will also lay the ground for additional funding for more comprehensive and interdisciplinary research designed around relay intercropping that will eventually promote robust IPM strategies in the region more effectively.