Published on Saturday, January 1, 2022
Over the last 25 years, soybean herbicide trait technologies have continued to increase and improve weed control options. However, the resulting chemical programs have relied heavily on the use of two products, glyphosate and glufosinate, as a base for weed control. As a result of the high demand and the challenges experienced over the last year and a half in both production and shipping, these two commonly applied herbicides are in short supply. Not only will getting these products likely be a challenge, but the price of these products has increased several times what they were in previous growing seasons.
With the concern over procurement and cost, it will be more important than ever to head into the 2022 growing season with a well-thought-out plan that maximizes the efficacy of each spray pass across the field. Early planning will provide the best chance to get products and allow time to source alternative products if necessary or even change soybean trait technologies.
KEY CONSIDERATIONS WHEN PLANNING FOR 2022:
First, it is important to remember the basics when controlling weeds to maximize crop yield potential. Starting with a clean field, free of early-emerging summer annual or winter annual weeds, is imperative to getting the crop off to a good start. If the specific herbicides that you use are not available or are price prohibitive, other options like tillage or other burndown herbicides, like Gramoxone®, may need to be incorporated into the program. In the end — start clean.
Second, include full rates of preemerge products that contain multiple sites of action (SOAs) against the most problematic weeds in a field. In many cases, burndown and residual products can be applied together, and the residual products can provide or contribute to burndown activity. Products like Sharpen® or metribuzin are great examples.
After crop emergence, monitoring weed emergence and growth is critical to controlling weeds when they are less than 4 in. tall. Many factors affect the control obtained from the post-emerge application, but targeting small weeds gives us the best opportunity to effectively control emerged weeds. However, this timing often occurs several weeks before crop canopy, making the inclusion of a residual product (usually a Group 15) in the post-emerge pass essential to help bridge this gap between spraying and canopy.
Crop canopy is an excellent tool for controlling weeds. Many of the environmental factors like rainfall and temperature that affect the development of full soybean canopy closure are out of our control. A few factors that can impact the time to canopy that are somewhat in our control include variety selection, row spacing, and early planting. An example of one of the best ways to reduce the time to canopy is to plant soybeans into narrow rows.
There are many unknowns going into the 2022 growing season. Go back to the basics of weed control and start with a clean field, apply full rates of pre-emerge products that have multiple SOAs against the most common weeds in your fields, and follow with a well-timed post-emerge application (including a residual product). With this approach, weed control can be successful while limiting the number of passes and use of hard-to-get products.
Author: Pat Holloway
Categories: CropTalk, 2021