A process for combating pests, especially fungi, which comprises applying to plants, seeds, or their loci, an isoxazolo [5,4-d] pyrimidine derivative having the formula: ##STR1## or a salt or optical isomer thereof, wherein R is alkyl or aralkyl, either optionally-substituted; R.sub.2 is hydrogen or alkyl; R.sub.3 is alkyl, aryl, alkylthio, alkanesulphonyl, alkoxy, aryloxy, cyano or optionally-substituted amino.
一种用于对抗害虫,尤其是真菌的过程,包括向植物、种子或它们的位置施加具有以下公式的
异噁唑并[5,4-d]
嘧啶衍
生物:##STR1##或其盐或光学异构体,其中R为烷基或芳基烷基,可选地取代;R.sub.2为氢或烷基;R.sub.3为烷基、芳基、烷基
硫、烷基磺酰、烷氧基、芳氧基、
氰基或可选地取代的
氨基。