Leafy spurge is off to a big start this year. South Dakota State University (SDSU) Extension Weed Specialist Leon Wrage said spurge's 20-foot deep roots give it a competitive advantage for soil moisture. The yellow-green bracts make patches easy to spot. Reduced grass growth makes the leafy spurge even more noticeable.
"Weedfighters are reporting that infestations seem more numerous and larger. Some of this is a perception because it's so easy to see," Wrage said. "Over 300,000 acres are infested, mostly in pasture, range and roadsides."
The yellow-green, terminal bracts, long, narrow, dark green leaves, and milky sap throughout the plant are identification features. The seed forms in three-celled capsules.
Though it is developing fast, there is a fairly wide opportunity to use herbicides before seed matures, Wrage said.
There is usually at least a three- to four-week period from when the first yellow-green color forms until seed becomes brown and is viable. During that period, true flowers form.
Control information is available at Extension offices. There is a spot treatment chart for mixing to treat patches with small sprayers or hand units. 2,4-D in spring and fall will stop seeding, Tordon is used for patches, Tordon + 2,4-D for large areas or setting the weed up for fall Plateau are useful options. The weed is tough so it is important to use all the tools available. Consider establishing a biocontrol site. Insects are being collected from established sites for redistribution -- contact your weed and pest supervisor.
"Keeping after the weed is really critical this year. Reduced grass competition will allow more than usual spread," Wrage added. "Grazing, mowing, a competition crop with tillage, and herbicide will fit into some plans." Always read and follow all herbicide instructions, Wrage said.
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