Fall Burndown Pays Off in More Ways Than One
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Wet conditions and delayed fieldwork gave weeds more opportunity for a fast start in many fields throughout the Midwest this year.
“On top of spring weather-related delays, many areas were tracking ahead on heat units, enabling larger winter annual weeds and earlier flushes of summer annuals,” explains Joe Bolte, market development specialist, Corteva Agriscience. “This placed more pressure on spring burndown applications, particularly in fields that weren’t sprayed for the first time until the end of May or early June.”
And when it came time for in-season applications, the excess moisture continued, presenting more challenges.
“New flushes of summer annuals such as waterhemp and Palmer amaranth continued to germinate as the residual activity from preemergence applications was exhausted from excess rainfall,” Bolte says. “The continuous weed pressure really showcased the importance of overlapping residuals and utilizing a full program approach for weed control. In-season residuals provide another layer of protection reducing germination of new weeds until canopy closure.”
The good news is that a fall burndown application can help reduce winter annual weed pressure before the next growing season starts. This practice will be especially beneficial in areas where planting is delayed or wet conditions prevent spring fieldwork.
“A fall burndown can help lay the foundation for a successful spray season next year,” Bolte says. “These applications also work great to control challenging winter annual weeds while they are small.”
Winter Annuals Bring Consequences Come Spring
Winter annual weeds, such as marestail and henbit, are often overlooked because they emerge once the growing season is over. However, dense mats of winter annual weeds may delay soil warming come spring, compete for water and nutrients during initial establishment of the summer crop, and result in poor seed placement at planting.1
Bolte says marestail is one of the most challenging winter annuals because of its wide germination window. Once marestail gets established in the fall, it will go dormant in the winter months. When it comes out of dormancy or “bolts” in the spring, it will be much bigger and more difficult to control. The weed also has been reported to be resistant to certain herbicides.
“If we have another wet spring and the planting season is delayed, the window to control winter annual weeds while they are small will be very limited,” Bolte says. “If left uncontrolled, the larger winter annual weeds may reduce spray coverage on the newly emerging summer annual weeds, leading to more weed escapes Certain winter annuals, such as henbit and purple deadnettle can also act as overwintering sites for pests like soybean cyst nematode, providing another critical reason to control winter annual weeds in the fall.”
Bolte recommends Elevore® herbicide for use in fall burndown programs. Elevore herbicide provides thorough control of both marestail and henbit without regrowth. This herbicide also is tank-mix-compatible with commonly used burndown and residual partners to control many ALS- and glyphosate-resistant species, plus marestail up to 8 inches tall. Elevore herbicide has a low use rate of 1 ounce per acre, making it an excellent fit in reduced- and no-till production systems.
And if you still have funds in yourTruChoice® offer account, a fall burndown can be a great way to spend them. Contact your Corteva Agriscience representative or visit Corteva.us to learn more about fall weed control options.
1 Werle, R., and L. Sandell. 2013. Managing Winter Annual Weeds Starts this Fall. https://cropwatch.unl.edu/managing-winter-annual-weeds-starts-fall
Elevore® is not registered for sale or use in all states. Contact your state pesticide regulatory agency to determine if a product is registered for sale or use in your state. Always read and follow label directions.
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