Spring is underway and with the warm weather starts the work on yards, fields and golf courses to grow grass and manage weeds. New Mexico State University Extension weed specialist and Assistant Professor Leslie Beck and research associate Matteo Serena are conducting a research project to find a better timeline for pre-emergence herbicide applications to help prevent weeds.
Beck and Serena focused their research specifically on prostrate spurge (Euphorbia maculata), a summer annual weed that begins showing up earlier in the spring season compared to previous historical information recorded.
“One of the big downfalls of prostrate spurge is that you really don’t want it to successfully germinate, because once it does that’s the beginning of a hard management process. Within a few weeks after germinating, it has already put thousands of viable seed back into the soil to germinate over the next few years, making management much more difficult in the future,” Beck said.
Serena and Beck began this project in March 2017 at NMSU’s Golf Course. The majority of the pre-emergence herbicide treatments that their research focuses on can be found in garden centers and hardware stores and can be applied by homeowners. For comparison purposes, their project also included active ingredients available only to licensed applicators and golf course superintendents.
“The research focused on different application timings with pre-emergent herbicides beginning with the earliest applications made on March 15, 2017. Herbicide treatments were applied at four-week intervals until Aug. 15, 2017. Some treatments only received the one single herbicide application, while other treatments received a sequential application of the same product three to four months later. We were trying to see which initial timing controlled spurge the best while maintaining an extended herbicide barrier on the soil surface that would prevent the weeds from coming up,” Serena said.
Most pre-emergence herbicides don’t have the ability to control a weed once it has germinated. So, if you can see it on the surface, it is too mature for the product to start injuring the root system. As a result, the timing of the application is crucial for success.
“The way these products work is when you make the application and water it in according to the directions in the label, it stays on the surface of the soil and creates a weed barrier. As weed seedlings germinate and pass through the barrier, they cannot survive as long as the herbicide is still active,” Beck said.
Beck said that by being more proactive against weeds, you are making it easier for yourself later down the line, which is what weed management is all about.
“If you consistently keep weeds at a manageable level whenever they appear, you are talking about maybe five minutes’ worth of hand pulling on a Saturday compared to setting aside an entire day of weeding your yard,” Beck said.
When it comes to homeowners applying herbicides to their yards, Beck said they need to pay close attention to and read the little booklets that are attached to the product.
“If people are selecting herbicides to control certain weeds, they need to read the label. Every product has a label with specific instructions on how to safely and successfully apply the product. Applicators should always, always read and follow the directions of the label prior to every application,” Beck said.
When Beck and Serena reviewed their results, they found that most of pre-emergence herbicide treatments were successful in preventing the germination of prostrate spurge when applied at the appropriate timing.
“Our results have shown that many of the herbicides we used were very successful and provided a weed barrier lasting between 60 and 90 days. With an early application in mid-March to early April, and a follow-up application in June or July, homeowners can protect their yards from germinating weeds. Moving forward from here, our future research will focus on rotating different herbicide treatments to avoid the development of herbicide resistance in the weeds by using the same product over and over again,” Serena said.
Their results on the golf course showed nearly perfect 5- by 5-foot squares with no weeds.
“It’s pretty exciting when we make an application in an area and by mid-May we can see perfect clean squares surrounded by a carpet of prostrate spurge,” Beck said.
Both Beck and Serena want homeowners to reach out to available resources if they have any questions or need any help when it comes to keeping their yards weed free.
“To anyone looking for recommendations for additional weed management you can contact your local county Extension agent or Master Gardeners. If the agent requires more specific or technical information they will contact and work with the specialists at NMSU to provide accurate information, and help you be successful in your yard management,” Serena said.