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ADDING ECOLOGICAL REALISM TO PLANT TESTING
Citation:
PFLEEGER, T. G., M. BLAKELEY-SMITH, D. M. OLSZYK, AND M. PLOCHER. ADDING ECOLOGICAL REALISM TO PLANT TESTING. Presented at SETAC North America 28th Annual Meeting, Milwaukee, WI, November 11 - 15, 2007.
Impact/Purpose:
Presentation
Description:
Current test protocols for the protection of nontarget plants used when registering pesticides in the United States and many other countries depend on two tests using greenhouse grown, agricultural seedling plants. The seedling emergence and vegetative vigor tests are used to assess the ecological risk of new or reregistered pesticides to the environment, in particular, to nontarget plants and plant communities. In an effort to bring more realism to plant testing protocols while maintaining simplicity and low costs, we are in the process of developing field methodologies to: 1) determine plant community responses resulting from single and multiple applications of herbicides and 2) develop methods appropriate for a Tier III field test. Three native plant species, (Festuca roemeri Roemer's fescue, Clarkia amoena Farewell-to-spring, Prunella vulgaris Self-heal), and one introduced species (Cynosurus echinatus Bristly dogstail grass) were started in the greenhouse in individual cells prior to transplanting. In 2007, seedlings were planted in two fields in the Willamette Valley, Oregon containing cover crops (Oregon State University Botany Farm and Hyslop Crop Science Farm). Individual plots at each site were prepared by removing vegetation within 1 m2 using a propane burner followed by hand weeding. One of each species was planted 10 cm a part in a square in the middle of each 60 cm x 60 cm plot. Every two weeks after transplanting, canopy volume was measured for each plant until frost. Ripe seeds were also collected over this time period. In 2006, only glyphosate was used at the OSU Botany Farm. In 2007, glyphosate at 0.01, 0.1 and 0.2 x FAR (32 fl oz/A; 2.2 Kg/ha) or aminopyralid at 0.037, 0.136 and 0.5 x FAR (7 fl oz/A; 0.5 Kg/ha) was applied either 1, 2, or 3 times, two weeks apart for a total of ten treatments per pesticide including the control. Preliminary results indicate that 1) native plants can be grown from seed for plant testing protocols, 2) field tests can be developed that add realism and are interpretable and 3) low levels of herbicides can change the dynamics of plant community development.