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Effects of Infection by Mycosphaerella graminicola on Translocation of Fluquinconazole in Wheat Seedlings

December 2000 , Volume 90 , Number  12
Pages  1,345 - 1,351

Richard J. Metcalfe , Michael W. Shaw , and Philip E. Russell

First and second authors: University of Reading, Department of Agricultural Botany, 2 Earley Gate, Whiteknights, Reading RG6 6AU, U.K.; and third author: AgrEvo U.K. Limited, Chesterford Park, Saffron Walden, Essex CB10 1XL, U.K.

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Accepted for publication 23 June 2000.

Translocation of 14C-labeled fluquinconazole was measured using combustion analysis and radio thin-layer-chromatographic analysis in seedling wheat leaves uninfected and infected with Mycosphaerella graminicola. Two isolates were used with differing sensitivity to demethylation inhibitor fungicides. Fluquinconazole was translocated acropetally, but not basipetally. Fluquinconazole 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 suggested that the accumulation was caused by a host response to infection. Infrared gas analysis showed that rates of transpiration and stomatal conductance in inoculated leaves were significantly increased very soon after inoculation but net photosynthesis was decreased. The actual mechanism of fungicide accumulation was not determined.

© 2000 The American Phytopathological Society