More restrictions for important fumigant
Metam sodium, commercially known as Vapam and other trademarked names, is one of the most widely used agricultural pesticides in the United States, says a U.S. Department of Agriculture scientist. As a broad-spectrum soil fumigant, it has been important to tree fruit and grape growers, providing control of nematodes, soilborne pathogens, and weeds. But changes are coming.
As part of the U.S. Environmental Protection Agency’s reregistration eligibility decision for soil fumigants in 2009, labels are being revised as the fumigants undergo reregistration. The revised label for metam sodium means that it is a restricted-use pesticide and all handlers must be trained before using fumigants, said Inga Zasada, nematologist at U.S. Department of Agriculture Agricultural Research Service’s Horticultural Crops Research Unit in Corvallis, Oregon.
If at any time a handler experiences sensory irritation, either an air-purifying respirator must be worn by all handlers or operations must cease, she said. After this, air-monitoring samples must be collected at least every two hours, and MITC (methyl isothiocyanate) levels must have decreased to less than 600 parts per billion in two consecutive samples taken at least 15 minutes apart. If the level exceeds 6,000 ppb, then all activities must cease and handlers must leave the site. Reentry is not permitted for five days after untarped applications.
Metam sodium is often applied to fields through chemigation, using a central sprinkler system. Some Washington State grape growers use metam sodium in the drip irrigation system to kill vines that are being removed later.
Zasada said that the buffer zones for water-applied metam sodium will likely be less than those for shank-applied metam sodium. Buffer zone requirements are expected to be included on soil fumigant labels in December 2011.
For more information, visit www.epa.gov/opp00001/reregistration/ soil_fumigants/handler/metam-handler-safety-info-11-2010.pdf .