The Effects of Diallate and Its Isomers on the Growth of Wild Oats

The growth of germinating wild oat seedlings (Avena fatuaL.) in soil treated with a range of concentrations of the individual isomers of diallate [S-(2,3-dichloroallyl)diisopropylthiocarbamate] and mixtures thereof has been studied. on the basis of diallate concentration required to reduce height by 50%, thecisisomer is less effective than thetransisomer by about 65%. A mixture of 42%transand 58%cisdiallate is shown to exhibit an antagonistic effect of about 95%. Thetransisomer is more effective than the 42/58 mixture by a factor of 2.6. It is shown that height vs concentration response curves can be represented by y = A {(x/C)B+ 1}-1, where y = height and x = concentration. A computer program has been developed to find the best parameters A, B, and C from any set of individual response data. A new technique for calculating synergism or antagonism has been employed in the part dealing with mixtures of diallate.