Researchers at the University of Tennessee Extension Service are studying up on which cover crops are best suited for early-season Palmer amaranth control.
While the weed pest has spread into further reaches of the Mid-South over the past several years, dedicated Extension agronomists have been coming up with creative crop protection methods. One such method has been the use of a cover crop to “drown out” young pigweeds before they can mature and produce more seeds.
“We’ve been evaluating four different cover crops – two grain crops, cereal rye and winter wheat, as well as two legume crops in hairy vetch and crimson clover,” says Matthew Wiggins, graduate research assistant at the University of Tennessee. “Our best early season weed control are coming from those cover crops that are producing the most biomass. In this case, we’re looking at cereal rye and winter wheat, because they are producing the most biomass.”
Wiggins says that vetch and clover are providing very good cover as well, but an unfortunate side-effect of planting the legumes is that researchers have seen a spike in pigweed germination in those cases.
“There is literature out there that suggests that Palmer pigweed likes to be grown in enhanced nitrogen amounts,” Wiggins says. “That’s going to be a concern for us moving forward.”
“Our best combinations that we’re seeing is where we’re actually growing a cereal crop and a legume together. That’s where we’re getting that added nitrogen benefit and not having nearly the carbon penalty on the front end, and we’re also still getting good residue amounts and contributing to early season weed control.”
Wiggins presented his research at a University of Tennessee Extension field day that focused solely on cotton and featured over 150 cotton producers and researchers in attendance.