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Cover crop cereal rye reduces waterhemp

A University of Missouri extension weed specialist says using cereal rye as a cover crop can help reduce waterhemp pressure without building its herbicide resistance.

Mandy Bish said fall seeded cereal rye accumulates biomass over the winter that suppresses waterhemp emergence. And she tells Brownfield pairing cover crops with a residual herbicide can ‘greatly reduce’ waterhemp germination.

“The less waterhemp that germinates, the less waterhemp you’re having to spray with post-emergent herbicides,” she said. “And repeated spraying of the same post-emergent herbicide over and over is where we tend to see resistance happen quickly.”

Bish said the cover crop’s biomass doesn’t impact soybean yields.

But she said the study, funded by the Missouri Soybean Merchandising Council, isn’t a silver bullet for stopping waterhemp.

“There was a level that we reached of waterhemp seed that cereal rye could no longer compensate or reduce those numbers,” she said. “So, I think knowing the soil seedbank and being familiar with conditions that you’re planting into is going to play a big part in how much you can rely on cereal rye for waterhemp suppression.”

Bish said her team saw decreased waterhemp presence in two of the three years studied.