Wisconsin Potato and Vegetable Weed Management Update
2022
- Department of Horticulture, UW Madison
Project Media
Highlights of our recent potato and vegetable research include:
• In the herbicide evaluation program, we’ve conducted field studies on over two dozen crops in recent years. This process typically starts with a multi-species herbicide screen, where we take a first look at many herbicide active ingredients across more than a dozen vegetable crops. Those that show promise are moved on to crop-specific replicated studies, and if there remains to be crop safety, added value for weed control and registrant interest, we then conduct refined studies to evaluate aspects such as crop variety tolerance, weed control spectrum, multiple soil types and viable use patterns (timing, rate, adjuvants, tank-mixes, etc.). We continue to work across regions to custom-tailor local solutions. While new herbicide active ingredient development is rather sparse in recent years, we still have several herbicides that are registered in other crops that look promising and are in various stages of the registration process. For example, in 2021 we began to evaluate a new herbicide proposed for use in potato that in Europe has already become the most widely used product for potato weed control. We’ll continue that work at multiple locations.
• We continue to work on ways to make small-seeded vegetables such as carrot, onion and cabbage more competitive with weeds in the early season and to optimize yield per unit of crop inputs, such as fertilizer and water. Our efforts recently have been focused on using natural plant growth regulators in combination with competitive varieties and seeding configurations to enhance production. We have a new graduate student starting on this project in 2022 and have established collaborations with researchers in multiple states.
• Similarly, we initiated work in 2020 to study the use of plant growth regulators to hasten uniform potato emergence and canopy development. The results of this preliminary study were interesting, suggesting that early-season potato growth can be significantly altered by low rates of plant growth regulator application. In 2021, we continued this work by looking at both seed and early foliar treatments and will follow these through harvest to determine tuber yield, size distribution and quality implications. In 2022, we’ll work to refine the application rates and timing that best improve competition with weeds while also monitoring tuber size distribution and yield.
With rapid spread of herbicide-resistant Palmer amaranth and waterhemp in central Wisconsin in particular, we anticipate continued adoption of synthetic auxin-resistant soybean. The applied research that we’ve recently conducted has been used to inform regulators, growers and processors about the risks associated with potential drift, volatility or tank contamination. We’ll continue to provide objective, science-based information to these important discussions such that they’re grounded in reality and not just marketing. Additionally, waterhemp management in potato and rotational vegetables will be an outreach focus in 2022 based on grower and consultant input.
• In 2021, we initiated preliminary investigations of using an interseeded rye cover crop in strip plantings every 4 potato rows or between each potato row as a potential mechanism to capture leachate below the potato root zone. One of the greatest challenges in mixed species cropping is herbicide selectivity – getting acceptable weed control without killing the cover crop. In 2022, we’re amending our methods to include fall-planted annual and perennial cover crops to improve that herbicide selectivity.
• We continue to lead related efforts and projects, such as serving on the DNR Groundwater Technical Advisory Committee and the Wisconsin IPM Program. We’re also now investigating potential economically viable alternative crops that could further diversify Wisconsin’s agricultural portfolio. In 2020, we established alternative crop studies in two central Wisconsin locations, Antigo and Arlington and continued this work through the 2021 growing season. The groundnut is of particular interest in the potato rotation and 2022 studies will focus on agronomic optimization of this crop that is a drought-tolerant, nitrogen fixing legume with high protein content.