University of Vermont

UVM Plant Diagnostic Lab Gets Grant to Conduct Compost Herbicide Tests

Burlington--The Vermont Agency of Natural Resources (ANR) recently awarded a $36,000 grant to the University of Vermont (UVM) Plant Diagnostic Clinic to test compost and compost feedstock for the presence of persistent herbicides.

Because these herbicides can cause injury to plants at extremely low concentrations, the potential exists to cause serious losses to gardeners and farmers, a situation that occurred in the state in 2012. The two-year grant will use plant bioassays to help isolate potential sources of herbicide contamination to help commercial composters ensure a high quality product.

"Currently, there is no easily accessible method for compost producers to have their product chemically tested in Vermont," explained Ann Hazelrigg, UVM Extension plant pathologist and director of the Plant Diagnostic Clinic, "although test methods are under development and should be available in the near future. Plant bioassays can be a reliable and quick method to determine if compost is going to cause harm to plants."

For a bioassay, plants are grown, under controlled conditions, in samples of compost or compost feedstock. The growth and health of these plants are observed over a four-week period to determine if persistent herbicides might be present.

"The replicated compost bioassays will offer valuable information to commercial composters by helping them to determine whether their sample contains persistent herbicides," Hazelrigg said. "Incorporating these tests into their production protocols will help ensure that their products don't contain levels of persistent pesticides that would cause harm to plants. It's a win-win situation for the composter and the consumer."

Dan Goossen, general manager of Green Mountain Compost in Williston, said, "We witnessed a significant amount of devastation caused by the presence of persistent herbicides during the 2012 growing season. Growth trials are the only sure-fire way to ensure that the compost you have is not going to negatively impact sensitive plant growth. We're encouraged that ANR has recognized the importance of this important tool and, through this grant, will be offering it to composters throughout the state."

For more information or to arrange to have samples tested, commercial composters should contact Josh Kelly, ANR Solid Waste Program, at (802) 522-5897 or by e-mail at