When the crops are off and the weeds are still growing, it’s time for burndown herbicides.

“Time and timing are important,” said Tim Stelter, Federated agronomist at the Osceola location. Federated’s custom applicators and growers alike have more available time in the fall; it’s easier to get applications scheduled and completed.

More importantly, some weeds (biennials and perennials) are better controlled with fall herbicide applications. “Marestail, dandelion, and white cockle are good examples of weeds that are easier to control in the fall,” said Stelter.

Stelter likened weeds to a bear preparing for hibernation – they take on nutrients to make it through the winter. “In the fall, everything goes down to the [weed’s] roots,” he said. Conversely, in the spring everything is coming up from the roots. This seasonal translocation within the plant means that fall is a great time to get at the roots of the weeds with burndown applications.

Fall burndown is good for row crops but also for grassy hay and “even Round-Up ready alfalfa,” said Stelter. Fall is a good time to control some of the unwanted weeds that lower the quality – and eventually the quantity – of the crop.

When it comes to choosing burndown products, “gone are the days of trying to save a few dollars by cutting [application] rates,” said Stelter. “We have to use full rates to kill the weeds.”

Federated Agronomists generally recommend any glyphosate product at full rate plus 2,4-D. Range Star® is another option; it contains 2,4-D and dicamba and is especially good for grassy hay fields and fall burndown in no-till situations (typically on soybeans, but not necessarily).

The window for fall application is, as usual, predicted by the weather. “We need to plan and make sure we have enough time and enough product on hand,” said Stelter. Let your Federated Agronomist know your plans before harvest begins.

Burndown is effective until there’s been a hard, hard frost. “We want actively growing weeds to make it effective,” he said.