Best Spring Herbicide Tips for Ryegrass Management
Managing ryegrass before planting no-till corn and soybeans has become more difficult for many growers, especially with increasing reports of glyphosate not performing as expected.
University of Kentucky Extension weed specialist Travis Legleiter notes that only about one-third of tested ryegrass samples are truly resistant to glyphosate. This indicates that application errors and environmental conditions are often the main reasons for poor results.
Weather is a key factor in determining herbicide effectiveness. Early spring conditions can be unpredictable, and cold temperatures—particularly at night—can significantly reduce glyphosate performance.
Applications made when nighttime temperatures fall below 40–45°F within a couple of days before or after spraying are more likely to be unsuccessful. For better control, herbicides should be applied when nighttime temperatures remain above 40°F, fields are dry enough for equipment, and ryegrass is still in its early growth stages.
Application rate is equally important. Many control issues arise when glyphosate is applied at lower rates, such as 0.75 to 1.0 lb acid equivalent per acre. Research shows that increasing the rate to 1.5 lb ae per acre provides more consistent results.
Since glyphosate products vary in concentration, growers should always calculate rates based on acid equivalent rather than product volume. Including 1% v/v methylated seed oil (MSO) can further enhance performance.
Although some farmers switch to clethodim after glyphosate failure, this is not ideal in cool conditions. Reduced activity and a 30-day planting restriction for corn limit its usefulness.
In resistant cases, alternatives like paraquat combined with atrazine or metribuzin may be more effective, though follow-up treatments and fall herbicide strategies can further improve long-term control.
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