On MeBr’s Turf

The next person who wins the Masters at eight under par like Jose Maria Olazabal did this year may want to thank the researchers looking for an alternative to methyl bromide for the turf industry.

Right now, the turf industry depends on methyl bromide in golf course and athletic field construction and renovation, from the historic Augusta National Golf Club, where the Masters is played, to neighborhood Little League fields. Turfgrasses are also principal vegetative covers for sites such as airports, parks, roadsides, cemeteries, and commercial buildings. In Georgia, there are an estimated 1.6 million acres in turfgrass. More than 53,050 acres in Florida are used for producing turfgrass sod, with a farmgate value of $499 million.

While there is no methyl bromide alternative right on the horizon for turf use, University of Florida Extension Turf Grass Specialist J. Bryan Unruh, who is in his second year of trials, has hopes of coming up with workable treatments.

“With turfgrass, we are dealing with some different issues because we are working with a perennial crop rather than an annual crop,” Unruh explained. “We really depend on methyl bromide when we establish new fields.”

In turfgrass, methyl bromide’s primary use is to eradicate weeds and undesirable grasses such as nutsedge and common and off-type Bermudagrass, although some nematode and disease control is also expected. Fields, especially putting greens, are expected to have a uniform surface and texture. To achieve that consistency requires the removal of all weeds prior to establishing a new grass, along with any grasses not of the planned variety. Currently, before certified planting material is planted on a field, it is treated with methyl bromide either by a hot gas or solid tarp method.

In the solid tarp method, liquid methyl bromide is injected into the soil at a depth of 8–12 inches, and then the area is immediately covered with a polyethylene tarp to retard the dissipation. In hot gas applications, a thin polyethylene drip tape in laid under a plastic tarp. Liquid methyl bromide is heated to produce a gas that diffuses into the soil. In both methods, the tarp is removed after a minimum of 48 hours and the soil is aired for at least 3 days before planting.

Unruh, and colleagues Barry Brekek and Joan Ducky, are testing 12 different treatments as possible alternatives, including dazomet, chloropicrin, metam sodium, methyl iodide, two “numbered” compounds, combinations of some of these chemicals, and some in combination with tarping.

“To our knowledge, we have the only large-plot trial looking at methyl iodide,” Unruh said. “And with a 1,500-square-foot plot, it is a very expensive treatment right now; at our experimental rate, it would cost $6,000 to treat an acre. Of course, if this proves to be a viable alternative, presumably the cost would go down.”

He is in the midst of analyzing the data from his first set of trials, which included three test sites—one in south Florida near Punta Gorda, one at the West Florida Research and Education Center in Jay, and one north of Savannah, Georgia.

“We have seen some differences between treatments. Tarped metam sodium co-applied with chloro-picrin, seems to show some promise, although without the tarp, the combination was ineffective,” Unruh said. However, he does not expect there will be a one-for-one replacement for methyl bromide. “And we’re certainly not likely to find anything with the same ease of handling and human safety,” he added.

Unruh is also looking at the possibility of using high-nitrogen organics like bone meal and blood meal as alternatives to methyl bromide. He is currently running greenhouse studies primarily to look at weed control. This year, he is testing 0.5, 1, 2, and 4 percent by weight high-nitrogen organics in a variety of soil types.

One advantage of using high-nitrogen organics is that they are also a source of fertility for the grass, he pointed out, which cuts down on the amount of other nitrogen fertilizer needed.

Unruh’s work is being supported by the University of Florida, the Golf Course Superintendents of America, and Hendrix and Dail, Inc., a major soil fumigation company that serves the eastern United States.

In the long term, finding a workable alternative to methyl bromide is really going to be essential for several segments of the turf industry, explained Steve Godbehere, research director at Hendrix and Dail. “Buyers expect certified planting material to be clean of any contaminants, so producers really need an alternative,” he said.

Once common Bermudagrass gets established, the stolons are very deep rooted and even multiple applications of herbicide will not kill it, making it a nightmare for those responsible for a smooth, consistent putting green surface.

And before golf course superintendents can change varieties to take advantage of new disease resistance and drought tolerance, they need to be able to eliminate existing stands. Right now, methyl bromide is the only viable choice, he explained. “There are alternatives that will take care of broadleaf weeds, but even Roundup doesn’t do the job on perennial and annual grasses,” Godbehere said.

In the short term, turf producers are suffering because of the price increases in methyl bromide as production cutbacks have come on line, he added. Already, fumigation costs have risen about 20–25 percent, according to Godbehere. “And growers are having to absorb it because they just can’t pass the increase along to the consumer,” he said. “The 50-percent reduction in 2001 will be a killer for the turf industry.”

Godbehere would like the U.S. Department of Agriculture (USDA) to consider funding more research that looks for a methyl bromide alternative for turfgrasses. “I’m not sure USDA understands how big the turf industry really is and how badly it needs an alternative,” he said.

Plant geneticist Wayne W. Hanna, who develops new turfgrass varieties at USDA’s Agricultural Research Service, Forage and Turf Research Unit in Tifton, Georgia, is looking at developing cultivars that are more competitive with weeds. Although not specifically because of the impending loss of methyl bromide, one of Hanna’s goals is developing turfgrasses that need fewer inputs, including pesticides.

“One of the traits we rate for as we develop new varieties is the ability to naturally crowd out weeds, and we do see great difference between grasses in the research plots,” he said. Hanna also sees the possibility of genetic resistance to nematodes. But, while more competitive varieties are on the horizon, they are at least 3 to 5 years away, and they will not, by themselves, eliminate the need for methyl bromide or an equivalently effective alternative, Hanna said.

Last Updated: July 1, 1999