Studies on the interactions between fungicides, <i>Alternaria tenuissima, Cladosporium herbarum</i> and <i>Microdochium</i> spp., on Fusarium head blight (FHB) development and deoxynivalenol (DON) concentration in grain caused by <i>Fusarium culmorum</i>
2012
Pirgozliev, S. R. | Ray, R. V. | Edwards, S. G. | Hare, M. C. | Jenkinson, P.
Saprophytic microflora and non-toxin producing <i>Microdochium</i> spp. capable of causing Fusarium head blight (FHB) have been suggested to affect the development of FHB caused by <i>Fusarium</i> spp., the occurrence of mycotoxins and the efficacy of fungicides for the control of the disease. The effects of metconazole and azoxystrobin on the interactions between <i>Fusarium culmorum</i> and <i>Microdochium</i> spp., <i>Alternaria tenuissima</i> or <i>Cladosporium herbarum</i> on FHB symptom development, <i>Tri5</i> DNA concentration and deoxynivalenol (DON) production were studied under glasshouse conditions. Results indicated that the sequence of infection of wheat heads and the relative timing of fungicide application can significantly affect FHB severity and the resulting mycotoxin contamination of harvested grain. Introduction of <i>A. tenuissima, C. herbarum</i> or <i>Microdochium</i> spp. to wheat heads at GS 57 before inoculation with <i>F. culmorum</i> at GS 65 generally resulted in increased FHB severity, <i>Tri5</i> DNA and DON concentration in harvested grain. The greatest increases of FHB severity (266%), <i>Tri5</i> DNA (79%) and DON (152%) were observed when <i>Microdochium</i> spp. were introduced first at GS 57 and <i>F. culmorum</i> inoculation followed at GS 65. Metconazole generally reduced FHB severity, <i>Tri</i>5 DNA and DON concentration in grain but azoxystrobin was most efficient at reducing DNA of <i>Microdochium</i> spp. in grain.
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