Effects of infection by Mycosphaerella graminicola on translocation of fluquinconazole in wheat seedlings

Translocation of C-14-labeled fluquinconazole was measured using combustion analysis and radio thin-layer-chromatographic analysis in seedling wheat l eaves uninfected and infected with Mycosphaerella graminicola. Two isolates were used with differing sensitivity to demethylation inhibitor fungicides . Fluquinconazole was translocated acropetally, but not basipetally. Fluqui nconazole accumulated around infection sites within 6 days after treatment. Accumulation occurred before M. graminicola hyphae had colonized the host mesophyll further than one host cell around the invasion site. This suggest ed that the accumulation was caused by a host response to infection. Infrar ed gas analysis showed that rates of transpiration and stomatal conductance in inoculated leaves were significantly increased very soon after inoculat ion but net photosynthesis was decreased. The actual mechanism of fungicide accumulation was not determined.