Best Practices for Effective Burndown in Warm Weather

By Blake Jackson

With warming temperatures, farmers are preparing to burndown fields and plant corn or soybeans, especially in southern Pennsylvania. Successful burndown requires careful attention to environmental conditions, weed size, and herbicide application.

Temperature significantly impacts herbicide effectiveness. Glyphosate and Gramoxone should only be applied when daytime temperatures exceed 55-60°F.

Warm, sunny weather enhances herbicide activity, while cold nights diminish it. 2,4-D is more effective in cooler temperatures, making tank mixing beneficial. After cold spells, wait for several warm, sunny days before application.

Weed size and growth stage also affect control. Smaller winter annuals are easier to manage, while perennials require larger sizes for systemic herbicide effectiveness. Flowering winter annuals or stressed weeds may need higher herbicide rates.

Herbicide application involves several considerations. AMS should be added to glyphosate, and a quality NIS to Gramoxone. Nitrogen solutions can be used as carriers but may reduce glyphosate's effectiveness. Sharpen requires MSO and AMS.

Tank mixing atrazine with Gramoxone improves its activity, but clay-based herbicides can hinder glyphosate. Flat fan nozzles are recommended for even coverage, with Gramoxone and Sharpen needing 15-20 GPA. Morning spraying is generally more effective.

Cover crop termination requires specific strategies. Glyphosate is most effective for cereal rye and other winter cereals, requiring warm, sunny conditions and appropriate adjuvants. Avoid tank mixing with liquid nitrogen or clay-based herbicides. Paraquat-based programs are an alternative but less consistent.

Annual ryegrass termination is critical due to its potential as a persistent weed. Glyphosate is preferred, applied during warm, sunny days to actively growing plants. High glyphosate rates and appropriate adjuvants are necessary.

Avoid liquid nitrogen and high rates of clay-based herbicides. Tank mixing glyphosate with Select Max or Resolve can improve control, especially in challenging weather.

Scouting fields before planting and spraying is essential for selecting the correct herbicide program. These guidelines help farmers optimize burndown applications for effective weed control and successful crop establishment.

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