Effects of infection time and moisture on development of ear blight and deoxynivalenol production by Fusariumspp. in wheat

Wheat ears were inoculated with conidia of Fusariumspp. at different growth stages between ear emergence and harvest and moist conditions were maintained for up to 7 days subsequently by mist irrigation. Of the fungi tested (Fusarium culmorum, F. avenaceum, F. tricinctum, F. sporotrichioidesand Microdochium nivale), only F. culmorumproduced ear blight symptoms and grain samples were found subsequently to contain deoxynivalenol. Most ear infection and deoxynivalenol formation occurred following inoculation at about mid-anthesis. Small amounts of deoxynivalenol were formed and some F. culmorumwas isolated even in the absence of ear blight symptoms. An overnight wet period was sufficient to initiate infection and deoxynivalenol formation but both were increased by extending the wet period up to at least 3 days. Recovery of Fusariumspp. from harvested grain was usually possible whether or not symptoms developed. F. culmorumusually persisted and often increased to moderately high levels after storage for 7 wk in a range of moisture conditions.