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USING POTATOES IN PROPAGATION TESTS FOR NONTARGET PLANT EFFECTS
Citation:
Pfleeger, T G., D M. Olszyk, E H. Lee, AND M. Plocher. USING POTATOES IN PROPAGATION TESTS FOR NONTARGET PLANT EFFECTS. Presented at Society for Environmental Toxicology and Chemistry, Portland, OR, November 14-18, 2004.
Description:
Current tests required for pesticide registration under the FIFRA only investigate seedling emergence and early growth. Previous research with sulfonylurea (SU) herbicides has shown that significant impacts can occur to plant reproduction with little or no visible effect on vegetation. Similarly, potato vegetation showed little impact while tubers were unmarketable when an SU herbicide moved off target in Idaho. Yield reduction can have significant economic and ecological effects, but is not evaluated under current test requirements. We have designed a plant propagation test that uses potatoes because they are economically important, easy to culture, and produce an asexual reproductive endpoint quickly. In a series of experiments during 2003 potatoes were grown in pots in the greenhouse, in pots outside and in an agricultural field at Oregon State University. Below field application rates (0.1, 0.018, 0.0032, 0.00056, carrier control and control) of herbicides (Oust?, Roundup?, Buctril?, and Rhomene?) were applied to the plants at 14 days post emergence or at flowering (~28 days post emergence). Plant height was measured at 14, 28 and 42 days after emergence. Plants were harvested about 120 days after emergence. Tubers were measured for numerous end points including specific gravity, fresh weight, number, size, and quality. The experiments indicated no significant response on potatoes from either Buctril or Rhomene. Potatoes were more sensitive to chemical treatment at 14 days than at 28 days post-emergence. There were significant loss in tuber fresh weight with Oust, and to a lesser extent with Roundup, at considerably less than field application rates (0.00056 rate for OUST in the field). Potatoes were more sensitive to Oust in the field whereas they were more sensitive in the greenhouse when treated with Roundup. In 2004, we hope to develop a correlation between tubers grown 120 days versus 42 days. This test lasting only 2 weeks longer than the current vegetative vigor test and would give regulators a new, cost effective tool to evaluate the risks associated with new chemicals prior to their release into the environment.