Agroscope, Institute for Plant Production Sciences IPS, 1260 Nyon, Switzerland

Effect of fungicides on fusaria of wheat

In 1998 and 1999 the influence of azole and strobilurine fungicides on wheat head blight was investigated. Artificial infections with Fusarium culmorum applied in growth stage (GS) 63-65 on wheat, assured the head blight infections. In 1998 the fungicides were applied on three different cultivars in GS 57 and GS 67. Applications with azole fungicides in GS 57 and GS 67 reduced the fusarium head scab by 29 % and 71 % and the deoxynivalenol (DON) content in the wheat grains by 9 % respectively 47 %. Strobilurine applications didn’t reduce the head scab severity in GS 67, but enhanced it by 50 % in GS 57. Moreover, these treatments provoked a DON increase of 50 % (GS 67) and 95 %(GS 57) and yield losses equal or 43 % higher than those of the untreated control. In 1999, only in one case out of four, we observed higher amounts of DON in wheat grains after the application of strobilurine fungicides. In contrary to 1998, a slight reduction of the head scab severity and of yield losses was observed with strobilurine fungicides. This effect was much lower than with azole fungicides and in most cases no reduction of DON was observed when strobilurines were applied. To prevent high DON contamination in wheat, we recommend to omit the use of strobilurine fungicides in fusarium risk situation, as corn in the preceding culture and no tillage soil management.

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