Abstract: 2-R-substituted-1,2,5-thiadiazole-3-ones have broad spectrum antibacterial and antifungal activity. They are especially useful in agriculture to protect plants against diseases such as leaf, stem, and fruit spotting, internal discoloration and decay of fruits and vegetables. These compounds are particularly active against diseases caused by the genera Pseudomonas, Xanthomonas, Erwinia, and Corynebacterium.