Journal of Plant Pathology (2011) 93, S7-S13

M. Beyer, F. Kiesner, J.-A. Verreet and H. Klink (2011)
Fungicide sensitivity of Septoria tritici field isolates is affected by an interaction between fungicidal mode of action and time
Journal of Plant Pathology 93 (1, Suppl.), S1.7-S1.13
Abstract: Sensitivity of Septoria tritici towards the fungicides trifloxystrobin, folpet, chlorothalonil, propiconazole, prochloraz, tebuconazole, epoxiconazole, and prothioconazole was tested in a bioassay using strains isolated in 1999, 2004, or 2008 in the high-disease-pressure and high-fungicide-input area between the North and Baltic Seas. The percentage of sprays containing at least one demethylation inhibitor (DMI, azoles) was never lower than 60% at any given point of time in the region where the fungal strains were sampled. Quinone outer binding site inhibitor (QoI) use was almost negligible in 1999, increased to about 80% in 2002, and subsequently decreased to 4% in 2008. The bioassay accurately detected the total loss of sensitivity of S. tritici towards trifloxystrobin as a representative of the QoIs that was previously reported. DMI concentrations inhibiting fungal growth by 50% (EC50s) decreased on the average by 48±17% between 1999 and 2004, and increased by 132±42% between 2004 and 2008 compared to 1999. EC50s of the multi-site inhibitors folpet and chlorothalonil increased by 128±25% between 1999 and 2004, and decreased by 40±11% between 2004 and 2008, but changes over time were non-significant for the multi site inhibitors. The period of QoI use approximately coincided with a small but consistent decrease of EC50s for all DMIs tested and with a small but consistent increase of EC50s for the multi site inhibitors.
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Database assignments for author(s): Marco Beyer, Joseph-Alexander Verreet

Research topic(s) for pests/diseases/weeds:
pesticide resistance of pest

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Pest and/or beneficial records:

Beneficial	Pest/Disease/Weed	Crop/Product	Country	Quarant.
	Zymoseptoria tritici	Wheat (Triticum)	Germany