Herbicide-tolerant turfgrass gets a setback

Columbus, OH — Even though the genetics are well understood and easy to select for, don't look for herbicide-tolerant grass any time soon, Penn State's David Huff told the 38th Annual Ohio Turf Conference held earlier this month in Columbus.

"In 50 years, we probably will have it. In 20 years, maybe. But in three to five years? I doubt it," Huff said. Huff is associate professor of turfgrass science at Pennsylvania State University. He specializes in turfgrass breeding and genetics.

According to Huff, it is not the ability to develop such grasses but the problems of controlling their spread and fixing liability for any escape that are the short-term hurdles.

A report published in the Proceedings of the National Academy of Sciences (PNAS) in October 2004 by L.S. Watrud showed that gene flow from genetically modified plants occurred up to 13 miles away — in just one year. The 300 acres for modified plants was surrounded by an 11,000 acre control area. (For details, see: "Evidence for landscape-level, pollen-mediated gene flow from genetically modified creeping bentgrass with CP4 EPSPS as a marker," PNAS, October 5,2004.)

"No one realized it could travel that far," Huff says.

The fact that it is a one-year study concerns some. Also, an aberrantly high amount of modified material was found in the farthest area, when compared to the several other areas closer to (but still outside) the quarantine area.

Gene stewardship is another concern. Part of the hubbub is that grasses are vegetatively propagated and their pollen can fly in the wind. Turf grasses are perennials and often grow close to native species. They can hybridize with those native plants.

On golf courses, such grasses are typically mowed low and often — eliminating seed production. But different uses, weather, economics, a labor strike or other reason might cause the property manager to "let it go" for a while.

If a problem occurs with seed dispersal, who is responsible? Huff asked. Is it the seed producer? The chemical company? The golf course or cemetery that allowed the escape?

In some areas, like Australia, bentgrass is considered a weed in pasture. They like being able to kill it easily with material like Roundup. What if a grass like annual bluegrass evolved tolerance?

"If I had to bet," Huff said, "I'd bet it would evolve tolerance."

Drift is a problem. How far from the margins of a herbicide-tolerant field do you stop spraying? What if a broad-spectrum material drifts onto non-tolerant lawns or flower beds?

Many people question the urgency of releasing a modified material that does not add food, fiber or medicinal value to society.

There is good news, though, Huff says. For one thing, gene mapping of agricultural grasses like corn, wheat, rye and rice will make it easier for geneticists to map field grasses.

No longer do geneticists look at single genes, but gene clusters. Called functional genomics, the microarray technology used might apply to turfgrasses. The networks of genes on corn and rice seem to occur in the same places as they do on, say, perennial ryegrass. This will allow turf researchers to learn quickly about where genes for disease resistance, seed yield, cold or shade tolerance and the like are located on turfgrasses, too.

Huff's bet is that, in the near term, researchers will look at networks of genes and use traditional breeding techniques to produce the turfgrass varieties industry needs.