Wallaces Farmer

Weed control starts in the fall

Utilizing a broad-spectrum fall (post-harvest), burndown can help reduce the soil weed seed bank by controlling winter annual and perennial weeds and offer several auxiliary benefits to row crop fields.

October 1, 2024

3 Min Read
Fall burndown considerations
Submitted by Beck's Hybrids

Beyond the goal of reliable weed control, a fall herbicide application can reduce host plants for pathogens such as Soybean Cyst Nematode (SCN), overwintering insects, and even diseases in warmer climates. It can also help maintain soil moisture in drought-stressed/arid climates, enable fields to be planted as soon as weather conditions allow, and help soil warming and drying in the spring, especially in no-till fields. The net result is more uniform crop emergence with fewer abiotic and biotic stressors.

Fall burndown applications start with identifying problem weeds for each field. Cool season (winter) annuals such as marestail, purple henbit, and Italian ryegrass are the primary targets of these applications. Depending on the geographic location of the field, the target weeds could change. These applications begin with a non-selective herbicide such as paraquat or glyphosate plus a residual herbicide to create a barrier for germinating seeds.

When targeting broadleaf weeds like marestail that can germinate over a long period of time, it is important to utilize a residual barrier that will be effective on small-seeded broadleaves. Some Group 14 herbicides, like flumioxazin, will accomplish this while adding some extra burndown power to the non-selective herbicide it is mixed with. If the target weed is a grass species, such as Italian ryegrass, a Group 15 herbicide will be needed to provide a residual barrier.

Poa or annual bluegrass can become a problem if left unchecked also. The addition of a Group 5 herbicide like metribuzin can be an inexpensive option that helps control bluegrass along with other broadleaf species such as common chickweed and purple henbit. Figures 1 and 2 show the power of adding two residual herbicides (Anthem® Flex and Valor®) to a fall burndown. These applications were made in early December, and the photos were taken in early April.

10.1_Becks_1700_-_Figure_1.jpg
10.1_Becks_1700-Figure_2.jpg

KEYS TO A SUCCESSFUL FALL BURNDOWN

  • Timing: Apply to emerged weeds post-harvest through early spring (avoid below-freezing temperatures and frozen ground).

  • Adjuvants: Adjuvants are recommended, especially when applying non-residual herbicides. Some glyphosate products have a built-in adjuvant and may not require additional surfactant.

  • Product Choices: Metribuzin will provide burndown and residual activity. However, the residual value won’t be as great as with some Group 2, 14, or 15 products.

  • Application Restrictions: Be mindful of plant-back considerations and maximum use rates, especially if a pre-plant burndown and/or a post-plant PRE will also be used. For example, if using a flumioxazin product in the spring, a different product should be applied in the fall.

Fall burndown applications are a smart management strategy that provides long-lasting weed control for cleaner, warmer seedbeds the following spring. CLICK HERE to view Beck’s 2025 Recommended Soybean Herbicide Recommendations guide. Always read and follow label directions.

Beck's - Farmers At Heart® - revolutionized the customer seed buying experience by remaining true to a foundation built on faith, family, and farming. Founded in 1937, Beck's appreciates the farmers who have helped them become the largest family-owned retail seed company and the third-largest seed brand in the United States. The Beck family is now in its fifth generation of family members who work in the business to honor God and help farmers succeed. The Beck family and team of employees help farmers achieve success from generation to generation through authentic customer experiences, product diversity, seed quality, and performance. With a home office located in Atlanta, Ind., Beck's serves farmers throughout the Midwest and Mid-South. For more information about Beck's Superior Hybrids, Inc., visit www.beckshybrids.com.

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