OREGON STATE UNIVERSITY

Weed may lessen environmental impact of paint

10/23/1998

MEDFORD - Slight variations within a plant family can make one plant a weed and the other a wonder. While farmers and ranchers across the West are spending millions of dollars trying to kill a weed called leafy spurge ("Euphorbia esula"), Oregon State University researchers have targeted a related plant, "Euphorbia lagascae," as a promising cash crop.

According to Richard Roseberg, crop and soil scientist at OSU's Southern Oregon Research and Extension Center in Medford, "Euphorbia lagascae" seeds contain high levels of epoxy fatty acids, or EFAs, substances in high demand for the production of paint and other coatings. The paint industry alone uses about 318 million gallons per year.

Research on such industrial crops is the result of work the U.S. Department of Agriculture did in the late 1950s and early 1960s, cataloging plants with unique compounds, Roseberg said. The attraction of "Euphorbia lagascae" is that it is drought-tolerant and produces oily seeds filled with an EPA called vernolic acid.

"The paint industry is interested in this plant's vernolic acid because it can replace some of costly and environmentally damaging drying solvents," Roseberg said. "The solvents now used come from either petrochemicals or are obtained through a costly process of changing soybean or flaxseed oil."

It is this drying solvent that accounts for the distinctive, and sometimes irritating, odor of paint that is drying, Roseberg added. These volatile organic compounds (VOCs) emitted from drying paint were targeted for reduction by the 1990 Clean Air Act amendments.

"One of the unique properties of the oil derived from 'Euphorbia lagascae' seeds is that it results in lower levels of VOCs in high-quality paint," Roseberg said.

He conceded that it would be an almost perfect plant if not for its unattractive habit of spitting seeds all over the field. This mechanism, which other plants in its family also develop, is called "shattering."

Mechanical pressure builds up as each pod reaches maturity. When the pressure is released, the pods spit the seeds 15 feet or more, thus propagating the plant. This is not a desirable characteristic for harvesting seeds. To counter this, Roseberg has successfully grown plots of the plant using a mutant variety developed in Spain. The variety holds its seeds long enough for harvest with conventional combine threshing machines.

"At current market values, a grower could expect to earn a gross return of about $365 per acre," Roseberg said. "However, southern Oregon growers could further profit by switching from water-intensive crops to 'Euphorbia lagascae.' It is both drought- and heat-tolerant."

He added that seed costs have yet to be determined, but because the plant produces so many seeds, the cost should be low. No special planting equipment will be required.

Remembering that it is related to leafy spurge and not native to the area, Roseberg keeps a close eye on his plots. He has done herbicide trials to develop management techniques, just in case he needs to stop the plant from spreading.