Bayer introduces new rangeland herbicide

Cattle ranchers and livestock grazers will soon have a new tool to reduce harmful invasive annual range grasses, while encouraging the growth of beneficial and more-nutritious perennials and improving the landscape.

Bayer’s brand-new range herbicide, branded Rejuvra, has been under development for 10 years. It was officially launched after receiving EPA approval June 15. It has also received approval from several state agriculture agencies and should receive more soon, according to Harry Quicke, vegetation management stewardship manager at Bayer. Quicke has been intimately involved with the program since joining Bayer 5 years ago. Large-scale testing began in 2015. Bayer’s research partners included 18 university departments and 12 federal agency, local government and non-governmental organization cooperators.

Quicke explains that the invasive annual grasses that degrade rangeland—cheatgrass or downy brome, Japanese brome, medusahead, ventenata and red brome—came mainly from the Mediterranean area originally and made their way out west by various routes.  They germinate in the fall, develop shallow roots in the early winter, and grow rapidly before perennials awake from dormancy. The annuals suck up water and nutrients before they can be utilized by native perennials, thus choking them out. “It’s as if they put the perennial grasses in a state of permanent drought,” said Quicke.

These invasive annuals “are a major threat to rangeland throughout the west,” according to Quicke. While some of the invasive annuals can be grazed by cattle and other livestock, they are less nutritious than perennials, causing the animals to eat more and further pressure the landscape.

They also typically thrive for only a few weeks during growing season. In land dominated by native perennials, there are spaces between individual plants, but invasive annuals fill in those spaces. When the annuals die in late spring or summer, they provide a continuous fuel source for dangerous wildfires.

Rejuvra works near the soil surface, said Quicke, stopping the annuals when they try to germinate. It can be applied at any time of year. When used alone it should be applied before the annuals germinate. One application at the recommended dosages can last for multiple growing seasons, the company says. The compound stays near the surface, in the shallow soil layer where annual root systems would otherwise flourish, and resists sunlight.

According to the product’s website, areas treated with Rejuvra in trials demonstrated a two-to-three-fold increase in perennial grass biomass, compared to untreated areas. By encouraging greater growth of perennials, Rejuvra increases the amount and quality of forage available to grazing animals, said Quicke. Animals who get high-quality, nutritious forage don’t have to eat as much.

The compound is not harmful to grazing livestock, Bayer says. Extensive tests have been done on the milk and meat of animals at test sites. There are no restrictions on the export of milk or meat from animals grazing on treated land.

But Rejuvra is not just for livestock growers. By actively encouraging the regrowth of native perennials, it restores the rangeland ecosystem. Quicke said that during range testing, it increased the number of flowers per plant and the leader growth on shrubs, thus providing a better environment for pollinators and other wildlife. Thus it is also of interest to managers of parklands.

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David Murray can be reached at [email protected].