Abstract
Effects of a fungicide, thiophanate methyl (Topsin-M) on the incidence of akakabi-disease (scab) and the contamination of trichothecene mycotoxins, nivalenol (NIV) and deoxynivalenol (DON) in wheat and barley were examined in 1982, 1983 and 1987 on the basis of three criteria: the damage of the disease in fields, Fusarium-infected grains and the mycotoxin levels in the harvested cereal grains. Application of Topsin-M twice at earing (April 15 to 22) and flowering (April 22 to 27) periods of the crops resulted in the remarkable decrease in not only the damage of the disease but also the contamination levels of the mycotoxins. The level of DON in the grains was highly correlated to that of NIV regardless of the application of Topsin-M, suggesting that the fungicide may equally inhibit the infection of F. graminearum producing either NIV or DON. Although the mycotoxins were found in harvested grains even when no incidence of the disease had been observed in fields, the co-occurrence of the toxins was efficiently depressed by the fungicide.
