On the Lookout for Glyphosate-Resistant Weeds

Published in the February 2014 Issue Published online: Feb 10, 2014

Glyphosate-resistant weeds were among the topics at the University of Idaho’s 2013 Snake River Sugarbeet Conference in Nampa, Idaho, on Dec. 17.

Such weeds have evolved the ability to withstand glyphosate, the active ingredient in Monsanto’s herbicide Roundup.

The Weed Science Society of America defines weed resistance as “the inherited ability of a plant to survive and reproduce following exposure to a dose of herbicide normally lethal to the wild type.” The evolution of Roundup-resistance in weeds is often linked to the use of genetically engineered Roundup Ready crops.

Wyoming Sugar Company became the first U.S. beet processor to approve the planting of Roundup Ready sugarbeets in 2007. Roundup Ready was introduced nationwide to growers during the 2008-09 crop season. Growers gain a broad-spectrum weed control with the use of Roundup. Other Roundup crops engineered by Monsanto include corn, soybeans and alfalfa.

Phil Stahlman, Kansas State University weed scientist, advised sugarbeet growers in attendance to avoid rotations with Roundup Ready corn.

Though no glyphosate-resistant weeds have been detected in Idaho, Stahlman suggests using pre-emergence herbicides and a weed control program with multiple modes of action. Beet growers should at least mix another product in the tank if they plant Roundup Ready corn seed.

In the nation’s Corn Belt, where growers often rotate Roundup Ready corn with Roundup Ready soybeans, three-quarters of growers surveyed by BASF Crop Protection suspect glyphosate resistance has made weeds on their farms more difficult to control. More than two-thirds of growers plan to apply pre-emergence herbicide this season. More than half intend to add another herbicide to their programs to prevent resistance. Half of growers also report they’ll use herbicides that attack weeds with multiple sites of action, and 47 percent will use overlapping residual herbicides.

Don Morishita, University of Idaho Extension weed scientist, also has concerns about Idaho rotations with Roundup Ready corn and sugarbeets. He advises growers to mix a chemical with a different mode of action in with Roundup.


Eye in the sky

Duke Bulanon, an assistant professor in mechanical engineering at Northwest Nazarene University in Nampa, spoke about monitoring crops using aerial imaging systems.

The Idaho researcher is developing an unmanned aerial vehicle that takes multispectral images that growers can use to determine the health of their crops.

Bulanon funded his two-year project with a $84,000 specialty crop grant from the Idaho State Department of Agriculture in 2012. He now needs help from growers to develop a computer software system that can interpret data.

The UAV, which has eight rotors and flies at heights up to 400 feet, has a multispectral camera that measures the energy characteristics of a plant’s surface.

Bulanon has used the apple orchards at University of Idaho’s Parma Research Station to test and perfect what he calls a flying crop-monitoring platform.

Bulanon believes the system can be used to detect diseases such as rhizomania in sugarbeets.

Other featured topics at the conference included the basics of resistance management, insect management, control of curly top and insect pests, nematodes, green manures as cover crop and salt accumulation effects on sugarbeets.