Effect of three foliar fungicides on germination, emergence, and internally-borne fungi in seeds from six cultivars of soybean

The purpose of this study was to determine the efficacy of foliar applications of thiabendazole (Mertect 340 F), benomyl (Benlate SO WP), and chlorothalonil (Bravo 6 F) in improving seed quality of six cultivars of soybean. Factors used to determine seed quality were germination, emergence, postemergence damping-off, and incidence of fungi associated with the seeds.

In the germination test, there were significant differences among cultivars, among treatments, and among replications. Germination of Forrest and Ring Around-501 (RA-501) was significantly higher than other cultivars. Thiabendazole gave a significantly higher mean germination than the other two fungicides, but was not significantly different from the control. Significant differences between replications were unexplained.

In the emergence test, Forrest and Essex had significantly higher means of emergence than other cultivars. Thiabendazole was significantly different from the control and chlorothalonil, but not from benomyl in increasing emergence. Differences between replications were less pronounced than in the germination test.

In the test for postemergence damping-off, Forrest had a significantly lower percentage of seedlings damped-off than the other cultivars. There were no significant differences between treatments or between replications.

There were no significant correlations between the incidence of fungi isolated and germination, emergence, postemergence damping-off, cultivar, treatment, and replication. Diaporthe phaseolorum var. sojae was found internally seedborne in 5.58% of seeds tested, and oospores of Peronospora manshurica occurred on 2.83% of the seeds. The mean percent of total fungi isolated was 19.58%.