Leafy spurge tests even the most experienced weed fighter. With a root system that can penetrate as deep as 29 feet and reproductive buds that can send up new shoots from 3 feet below the soil surface, this nonnative perennial can survive extreme drought or months of flooding. Dense infestations often create biological monocultures fit for neither livestock grazing nor wildlife.
“The financial losses can be severe,” says Scott Flynn, field scientist with Corteva Agriscience. “Production losses are most obvious, but the economic value of the land can drop significantly. And then there are environmental losses, which range from reduced species diversity to habitat destruction.”
Research shows that deer use of habitat infested with leafy spurge was 82 percent lower than noninfested habitat. Leafy spurge can reduce forage production by as much as 67 percent. Both outcomes concentrate livestock and wildlife in noninfested areas, initiating a domino effect: Increased stress on desirable plants in weed-free areas makes them more susceptible to advancing leafy spurge and invasion by other nonnative species.
The good news is, you can control leafy spurge, and you can restore habitat and forage production,” Flynn says. “But success requires commitment.”
For more than 30 years, Tordon® 22K herbicide has been the foundation of any successful leafy spurge management program. But now Tordon 22K has a new partner — GrazonPD3™ herbicide — to combat this notorious, invasive weed.
GrazonPD3 is a convenient premix of the active ingredient in Tordon 22K plus 2,4-D choline. Research shows that including 2,4-D in treatments with Tordon 22K improves leafy spurge control in-season and long-term.
GrazonPD3 is a low-odor, high-load formulation, allowing for a lower use rate and less packaging. The formulation also is less volatile and carries a reduced signal word, compared with the old standard, Grazon® P+D herbicide.
Improved control and convenience make GrazonPD3 your best option for broadcast applications across large, dense, established infestations. Use GrazonPD3 at 40 fluid ounces per acre to control leafy spurge before flower. For fall application apply 40-80 fluid ounces per acre after the first hard freeze. Broadcast applications of GrazonPD3 will thin leafy spurge stands each year, increase grass production and improve forage utilization.
When spot-treating small patches or where new infestations pop up, go with the rate flexibility of Tordon 22K (apply 1 to 2 quarts per acre). The goal with spot treatments is to eliminate the patch as quickly as possible.
“It never will cost less than it does today to control leafy spurge,” Flynn explains. “Spot-treating smaller infestations with Tordon 22K gives us the opportunity to nip leafy spurge in the bud, so to speak. With GrazonPD3, reclaiming larger areas previously lost to leafy spurge — and gradually gaining back production — is a more economical longer-term approach for broadcast applications.”
Proper treatment timing is critical for success against leafy spurge, Flynn notes. In the spring or early summer, treat at true flower stage (after yellow bract forms) and while plants are developing. Fall also is an excellent time to control leafy spurge. Treat after the stems have developed regrowth.
“It’s important to remember that good grazing management, resulting in a competitive grass stand, can help hold down leafy spurge and make herbicide treatments more effective,” Flynn says. “There is no ‘silver bullet’ to control leafy spurge. Ultimately, you can control leafy spurge and reclaim infested areas for livestock grazing and wildlife habitat. But you must be diligent, and stay committed to a long-term management program.”
Broadcast recommendation: Broadcast recommendation: Use GrazonPD3 at 40 fluid ounces per acre to control leafy spurge before flower. For fall application apply 40-80 fluid ounces per acre after the first hard freeze.
Spot/patch recommendation: Apply 1 to 2 quarts of Tordon® 22K herbicide per acre
* The use rates for Tordon 22K, which were identified in this article that ran in Range and Pasture Steward Magazine and The Pasture Advisor on 6/1/2020 and 6/8/2020 respectively were mistakenly incorrect. This version of the article has been updated and contains the labeled use rates. Always read and follow label directions.
GrazonPD3, Tordon 22K and Grazon P+D are federally Restricted Use Pesticides. GrazonPD3 is not for sale, distribution or use in Nassau and Suffolk Counties in New York State. Always read and follow label directions.