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Select the best control for volunteer Enlist corn
Not all herbicides are equal when it comes to controlling volunteer Enlist herbicide-resistant corn, according to new research at the University of Guelph.
Two of five herbicides tested in field trials conducted in 2013 and 2014, including Bayer CropScience’s Select and BASF’s Poast, performed very well. They belong to the cyclohexanedione herbicide class in Group 1.
The remaining three, Dupont’s Assure, Bayer CropScience’s Excel Super, and Syngenta’s Venture, were not effective. These herbicides are part of the aryloxyphenoxypropinoate herbicide family, also in Group 1.
Enlist corn was approved for use in Canada in 2012. It is specifically designed with transgenes to resist not only glyphosate (Roundup), but also the common systemic herbicide 2,4-D. Enlist corn hybrids, stacked with multiple herbicide-resistant traits, provide Ontario corn growers another weed management tool.
Lead researcher Professor Peter Sikkema, from the Department of Plant Agriculture, says that farmers who use Enlist corn hybrids before seeding soybeans the following spring will have to adjust for the differences in herbicide efficacy.
Because glyphosate resistance has become an increasing problem in the province, Sikkema thinks that although Enlist corn hybrids will offer growers a new weed management strategy, they will also have to adjust their volunteer Enlist corn management program.
Collaborating on this study is plant agriculture professor Nader Soltani. •
The fight against weeds
Weeds that compete with cash crops, such as soybeans, often seem to get the upper hand. Now, the reasons for that advantage are starting to become clear.
Plant agriculture Professor Clarence Swanton at the University of Guelph says the competitive relationship between soybean plants and weeds can be explained by understanding light quality.
Visible light is measured in wavelengths that correspond with colour. Red and far-red wavelengths have the greatest impact on plant growth by activating phytochrome, the plant’s photoreceptor pigment responsible for regulating development processes.
Swanton and graduate student Jessica Gal found soybean plants in a growth chamber could sense weeds’ presence, because the weed leaves altered the amount of red to far-red wavelengths reflected at the plant.
When they sensed that, they worked to grow taller, to out-compete the weeds; however, as the stem elongated, root biomass was reduced. That left less room for nitrogen-fixing nodules to develop and convert nitrogen into a form the plant could use.
“This reduction in nodulation leaves plants vulnerable for stress,” says Swanton. “That stress can lead to significant yield loss, and explains why weeds appear so strong.”
Swanton says these findings reinforce the principle of good weed management.
Funding for this research was provided by NSERC and Syngenta. •
Research Roundup is provided by members of SPARK (Students Promoting Awareness of Research Knowledge) at the University of Guelph’s Office of Research. For more information, contact a SPARK writer at 519-824-4120, ext. 52667.