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Cold weather weed concerns

By Matt Reese

As wet, cold, windy weather lingers into May for much of Ohio, there are growing concerns about the growing weeds in unplanted fields.

“We always get questions about the cold weather. We had a warm winter and we actually have winter annuals larger than they have been in other years. I have been hearing about chickweed that is 8 to 10 inches tall, which makes for a really challenging burndown situation. A lot of times, you can take those down really fast in warm weather with the right herbicides,” said Mark Loux, Ohio State University herbicide specialist. “Cool weather is a big concern and then wet weather is another challenge. It is hard to give really concrete guidelines in this situation. If it is hitting freezing at night, cloudy in the day and 40 or 50 degrees, that is obviously not a good situation to spray and you probably want to wait that out. If it is 55 or 60 degrees during the day and 40 at night, maybe you should spray, especially if the weather forecast gets colder.”

In cold conditions, increasing rates and mode of action complexity can help compensate.

“If you spray in cold weather, make it a more complex mix to give an added boost. For example, instead of glyphosate and 2,4-D, do glyphosate, 2,4-D and metribuzin or Sharpen. That is the also the recommendation for big weeds. You want to make it more complex and you want to bump your rates,” Loux said. “Gramoxone, metribuzin and 2,4-D can work in that situation once we hit warm and sunny weather to burn things down faster. Bump your glyphosate rates, put the Sharpen in and make it more complex and more aggressive.”

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