Dr. D.G. Crosby and Richard Higashi, environment to estimate Department of Environmental environmental effects when pesticides Toxicology, check over a small are applied. laboratory model of a rice

The objectives are: (I) to identify and study the environmental factors that govern the movement and chemical destiny of pesticides applied to rice fields, (2) to estimate the importance of these factors to the practical use of specific rice pesticides, and (3) to apply these results toward meeting regulatory requirements as well as to improve the management of rice pesticides.

Duter

Accurate prediction and accounting for pesticide residues is very important to succesful pesticide management. Studies with Duter were continued in 1982 which confirmed the previous year's work that this chemical is stable to microbial methylation in rice field soils, but the soil unexpectedly causes non-biological degradation to nontoxic products. The rapid breakdown of Duter indicates this chemical is not likely to be a problem to non-target organisms except immediately following application.

MCPA

Studies on aquatic and atmospheric degradation of MCPA were completed in 1982. They confirmed the previous year's work that MCPA degrades to a series of unstable products. These products further degraded in a sequence to a very unstable intermediate with a half-life of only a few minutes and then to a mixture of fatty acid fragments. All but one breakdown product is less stable than MCPA to degradation and it dissipates rapidly. The one minor persistent product has so far been undetectable in the field. It appears that no degradation products will build up in the environment.

The rapid breakdown of Duter indicates this chemical is not likely to be a problem to non-target organisms except immediately following application.

Laboratory Rice Field Environment Chamber

It is exceedingly difficult and expensive to make predictions and comparisons of the environmental fate of pesticides in rice fields. A small laboratory model of a rice field was designed and tested in 1982. It is a 20 gallon all-glass aquarium equipped with an airtight cover, temperature controls and measuring devices. The chamber was tested using molinate at a concentration similar to that used in rice fields. The volatilization loss was measured and found to be similar to results found from field studies. Ordram l 0G also produced results similar to those from field applications. These results, while still preliminary, are quite promising. They will alow estimation of the effects of temperature, air velocity, and applcation rates quickly and more accurately than in the field. This opens the way toward measuring the effects of changing these and other variables on residues in rice fields and river water.

Rice Pesticide Information System

A rice pesticide information system to provide a readily-accessible file of scientific reports and articles for rice researchers is under development. New scientific and regulatory information from this system can be transmitted to industry by the Cooperative Extension rice specialist and farm advisors. MCPA was the first pesticide used for this system, and several hundred abstracts and articles already have been accumulated.