By speaking with alfalfa growers, Leslie Beck, NMSU Extension Weed Specialist, has found that plantain weeds pose the biggest concern to growers. Plantain weeds are notoriously difficult to control and have really deep roots that can grow back season after season. Beck hopes her research will help to find out which herbicide will best control these weeds without causing harm to alfalfa yields. (Photo courtesy of Leslie Beck)
Las Cruces, NM (July 30, 2018) - New Mexico State University Extension Weed Specialist and Assistant Professor Leslie Beck has received funding for the second year in a row through the U.S. Alfalfa Farmer Research Initiative. Beck was one of five researchers chosen by the National Alfalfa & Forge Alliance to receive funding.
Beck, along with co-principal investigators Mark Marsalis and Leonard Lauriault, will receive $8,580 for 2018-2019 to continue their search for herbicides that best work on controlling perennial weeds like plantain with little to no damage to alfalfa yield.
During Beck’s first year of funding, she began mainly looking at the herbicide Sharpen, which has recently been labeled for weed control in dormant season alfalfa in New Mexico.
“Herbicides need to be applied in the winter during the slowed growth of alfalfa to avoid injury to the crop,” Beck said. “However, some areas of New Mexico may not get winter temperatures that are cold enough to achieve true dormancy. This increases the possibility of alfalfa injury when dormant-season herbicides like Sharpen are applied because the alfalfa is still green.”
Not only are weeds in general a problem for growers, Beck’s research focuses on management options for one particular type of weed that is known to be difficult to control in alfalfa.
“Weeds are always a big concern and perennial weeds in particular pose added problems for alfalfa growers,” Beck said. “In speaking with growers, it seems that the plantain weeds are notoriously difficult to control. They have really deep roots that can grow back season after season. In order to control the weed, the root must be damaged.”
What led Beck to decide to test the herbicide Sharpen was how poorly other broadleaf herbicides have worked on controlling plantain in the past.
“The reason herbicides like Sharpen are labeled for dormant season applications is that the plant slows its growth and ‘hibernates’ during the cold winter temperatures and grows back from its root system when temperatures are ideal again in the spring,” Beck said. “Applications of these herbicides to green alfalfa tissue can result in injury and reduced yield.”
Beck used mature alfalfa fields that were over 3 years old in Los Lunas for the field research trial. Due to a lack of uniform plantain coverage within alfalfa fields needed for a replicated study, she developed a separate study on plantain weeds grown in the greenhouse.
“We grew the weeds from seeds at the end of summer and made our herbicide applications to the weeds in the greenhouse at the same timing that we applied the treatments in the field so that the timings of the treatments were the same,” Beck said. “To mimic fall environmental conditions in the greenhouse, we limited the amount of sunlight to the mature weeds to reflect the decrease in daily sunlight in the fall and winter months.”
When it was time to harvest the alfalfa, Beck saw some promising results along with the potential for further research to continue evaluating the efficacy of these herbicides on plantain control in alfalfa.
“In the field trial, we didn’t observe noticeable injury or decrease in yield as a result of the herbicide treatments, which was really encouraging,” Beck said. “In the greenhouse trial, we saw some definite injury, though not generally enough to prevent the survival and recovery of the weed.”
For the second grant, Beck wanted to look at additional applications and look into combining Sharpen with different herbicides to see if control of the plantain weeds in the greenhouse could be improved. These questions led to the submission of the second grant application for research, which was recently approved for funding through the National Alfalfa & Forage Alliance’s U.S. Farmer Research Initiative.
“What we plan to do is to observe Sharpen applications alone or in combination with other labeled herbicides,” Beck said. “Additionally, we plan to look at sequential applications of herbicides to see if there is an increase in the efficacy of the herbicides on plantain with minimal injury to the alfalfa.”
If Beck is able to find the perfect combination of herbicides, it could add another useful tool for alfalfa growers in the constant fight against weeds.
“Plantain is the number one weed problem relayed to me by alfalfa growers in New Mexico,” Beck said. “Even Round-Up isn’t having much of an affect in Round-up Ready alfalfa systems.”
Beck said it’s encouraging for her to see that people want her to continue her research and looks forward to what comes out of her second round of testing.
“I’m really interested to see how taking weed management further, and continuing to tweak pre-existing weed management practices, is going to improve our ability to manage weeds in agriculture,” Beck said. “I look forward to this next year’s research and how we can continue to enhance weed management strategies for growers in New Mexico.”