June 12, 2003

 

Researchers Gaining Ground on Leafy Spurge Control

Progress continues in the battle to control leafy spurge in North Dakota, according to a North Dakota State University weed scientist. "We now have enough tools in our toolbox so that anyone that wants to control leafy spurge, can do it," says Rod Lym, NDSU professor in the Plant Sciences Department.

In his most recent research, Lym found a combination of herbicides that extends leafy spurge control for more than a year. The treatment consists of Tordon plus Plateau and 2,4-D applied with a methylated seed oil (MSO) adjuvant. Research results show 92 percent leafy spurge control after three months, 83 percent after twelve months and 75 percent control 15 months after application. With the traditional treatment of Tordon plus 2,4-D, control would have been near 0 at 15 months with a single treatment.

The combination has been studied for several years and at different locations around the state. "In some cases we’ve been able to go up to three years before we’ve had to spray the area again," Lym says. "Several counties have now switched to this treatment rather than using the traditional treatment which was a combination of Tordon and 2,4-D in June. The three-way combination works well in the spring but not for fall treatments of leafy spurge. At one point, Tordon applied at two pounds per acre was also very effective but using that high rate has been banned by the Federal government."

Research on leafy spurge is also ongoing in other areas at NDSU. It involves biocontrols such as using the flea beetle and seeding competitive and native grasses to stop the spread of leafy spurge.

"Currently we’re in the third year of a five year study which combines the use of flea beetles, herbicides and competitive native grasses," Lym says. "We now have data showing that these combination gives us more rapid and long-term control."

Research using sheep and goats to control leafy spurge has also shown positive results. Grazing will not eliminate leafy spurge; however it will decrease the density. One area where grazing has worked well is at Camp Gilbert C. Grafton, the home of the North Dakota Army National Guard’s engineers. After four years, control was 80 to 90 percent and herbicide costs were reduced by $20,000 or more.

The Sheyenne National Grassland in southeastern North Dakota is an area where leafy spurge control has been difficult. "The soil is too sandy for flea beetles to do well and Tordon can’t be used in many areas because the water table is too high," Lym says. "However, research is continuing. The herbicide Plateau can be used and has shown good results".

Lym has been researching leafy spurge control since 1979. "Leafy spurge data goes back to the 1930s and 40s, however hard data beginning in the 1960s shows that acres infested with leafy spurge were doubling every 10 years. That has decreased dramatically so that now some counties are reporting a decrease in the number of infested acres. If the doubling trend had continued, North Dakota may have had 3.4 million acres of leafy spurge by now, rather than the current estimate of 1.3 million acres. The reduction in spread is due to the combined efforts of research, coordination and cost-share programs from the state Agriculture Department, and on work by county weed officers and land mangers state-wide."

Lym recently returned from a trip to the Baldhill Dam north of Valley City. "At one time the road between Valley City and the dam was solid leafy spurge on both sides of the road. Now there are just areas of scattered plants. The combination of flea beetles and herbicides has worked well. The most successful programs have combined as many tools as possible to control leafy spurge. You can’t build a house with just one tool and you cannot get long-term leafy spurge control with just herbicides, biocontrol agents, or grazing animals used alone."

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Source: Rod Lym, (701) 231-8996, rod.lym@ndsu.nodak.edu
Editor: Rich Mattern, (701) 231-6136, richard.mattern@ndsu.nodak.edu