It’s easy to understand why cereal rye makes up 44% of all U.S. cover crop acreage. It produces large amounts of biomass, reduces soil erosion, and suppresses weeds. But could the same traits that make it a popular cover crop also make it a future weed problem? Researchers at Auburn University compiled an overview of previous research to provide an answer.
A thorough management plan is the key to keeping this cover crop on the right side of farming. Farmers should focus on proper cereal rye isolation distances, termination timing, and cover crop rotations or mixes to maintain control over cereal rye. Meanwhile, researchers need to develop cereal rye varieties that are unable to hybridize with other weeds or wild biotypes, Maity says.
Maity’s research comes as cereal rye use rapidly rises across the U.S. This increase raises the risk of cereal rye exchanging genes with feral rye, Maity explains.
The Dangers of Invasive Cereal Rye
Cereal rye’s greatest threat potential lies in its genetics. Cereal rye hasn’t been as thoroughly bred as other crops, which means that it can crossbreed with feral rye, a well-known weed. Researchers worry that cereal rye could become unmanageable and outcompete cash crops if it develops weedy traits like delayed flowering and seedhead shatter. Already, feral rye is considered a serious noxious weed threat for growers in western regions of the U.S., due to the difficulty of managing it in wheat fields.
“Cereal rye and feral rye are intercompatible,” Maity explains. “So if we do not pay close attention to those ecological and genetic details, there is a high chance of intensive cultivation [of problematic hybrids].”
Cereal rye wouldn’t be the first plant ally to turn villainous. Johnsongrass, kudzu, and cogon grass were all initially introduced to the U.S. with great hopes for their farming or ecological benefits. They now wreak havoc on farms and ecosystems throughout certain regions of the country.
Cereal rye is similar to these once-handy, now-invasive plants, in the sense that many of the traits that contribute to its effectiveness as a cover crop could also make it a nuisance if it became uncontrollable. This cover crop has a tolerance to drought and cold weather, a deep root system, some seed dormancy, and known herbicide resistance to mesosulfuron and tribenuron.
How to Grow Cereal Rye Without It Becoming Weedy
Don’t abandon that cereal rye seed just yet! Proper management can help keep cereal rye from becoming an unwelcome sight in the field, Maity says.
Farmers who plant cereal rye should check for feral rye within roughly 980 feet of the field. This helps prevent any weedy rye hybrids. Farmers also shouldn’t delay cereal rye termination to boost biomass for so long that seeds start to set. “If there are any outcrossings with feral rye, that means those hybridized flowers are going to seed.” Maity explains.
Terminate cereal rye when 10% to 20% of the plants start flowering to prevent any hybridized cereal rye seeds from reaching the seedbank.
Cover crop rotations and mixes can help reduce reliance on this cereal rye, Maity says. Mixtures help capitalize on benefits such as nitrogen fixation that cereal rye alone might not offer. (Read more about a nitrogen-fixing cereal rye mixture in our recent news article.)
Researchers, too, will need to adjust how they approach cereal rye. Cereal rye’s nuisance traits require more research, Maity says. Universities and research centers could organize a cereal rye breeding program to lessen cereal rye’s ability to cross-cultivate with feral rye. Meanwhile, universities could also create distribution maps of feral rye to help farmers better understand the risks of rye hybridizing in their area.
Research has already emphasized the benefits of cereal rye, Maity explains. Now research must emphasize proper management to ensure that cereal rye doesn’t become the next johnsongrass.
Explore GROW’s website for more information on cover crop management and termination.
Article by Amy Sullivan, GROW; Header and feature photo by Aniruddha Maity, Auburn University.
