BAS 490 02 F, a new fungicide to control scab and mildew in apple and pear

BAS 490 02 F, a WG formulation containing 50 % of kresoxim-methyl is a representative of a new fungicide family, the strobilurines. Kresoxim-methyl, a development of BASF, is a synthetic analogue of Strobilurine A, a natural antifungal metabolite of the fungus Strobilurus tenacellus. The biological activity of kresoxim-methyl, applied under the code number BAS 490, was evaluated for several years against apple scab and powdery mildew at the Research Station of Gorsem. Besides a direct preventive effect on spore germination, the product prevents the formation of conidiophores and conidia after curative application. At a rate of 100 g a.i/ha, kresoxim-methyl gave excellent control of apple scab in different preventive and curative schedules. Under conditions of normal infection pressure, this rate also gave satisfactory control of powdery mildew. Kresoxim-methyl is selective for the predatory mite Typhlodromus pyri and can be applied without risk of phytotoxicity to the most important apple and pear varieties. To control fungi which need several treatments per season the new biochemical mode of action will be useful in minimizing the risk of fungicide resistance to the single-site fungicides which are at present at our disposal.