Journal of Plant Pathology - Sipav.org

S1.10 Fungicide sensitivity of Septoria tritici Journal of Plant Pathology (2011), 93 (1, Supplement), S1.7-S1.13
were transferred into each well. All experiments were
conducted with four replicates. The gap between microtiter
plates and lids was sealed with parafilm and
plates were incubated on an orbital shaker at 120 rpm,
22°C, and an 8-h photoperiod for 5 days. Subsequently,
the optical density of the spore suspensions and the respective
control liquids was determined using the absorbance
reader mentioned above.
Statistics. Optical densities were corrected for the
absorbance of the microtiter plates, the medium, and
the intrinsic colour of the fungicide. Data were expressed
relative to the optical density of the untreated
control. Medians and standard errors (SE) of the data
originating from the strains isolated in the same year or
for each individual isolate were calculated and plotted
against fungicide concentrations. Fungicide concentrations
reducing the optical density of the spore suspension
by 50% (EC 50
) were estimated using the sigmoid
regression models of software package Sigmaplot 10.0
(Systat Software GmbH, Germany). Changes in EC 50
over time were compared by Kruskall Wallis tests at P <
0.05 (2-sided). Effects of the interaction between time
and fungicidal mode of action on EC 50
were calculated
by two factorial analyses of variance (ANOVA). Since
EC 50
s were characterized by outliers, data were logtransformed
prior to ANOVA to obtain approximate
Gaussian distributions. ANOVAs were carried out using
the statistical software package SPSS 16 (SPSS Inc.,
USA).
multi-site inhibitors chlorothalonil and folpet were not
significant, irrespective of year (Table 1).
The EC 50
for trifloxystrobin was 0.4 mg ml -1 in 2006 (N. Scheider, personal
communication) and >1.3 mg ml -1 in 2008. (Figs.
2C, 3A).
Effects of fungicide and year were significant at P
0.4 mg m -1 in 2006 (N. Scheider, personal
communication) and >1.3 mg ml -1 in 2008. B. Changes in
DMI and QoI use in Northern Germany between 1999 and
2008. Data were extracted from the annual reports of plant
pathology unit of the administrative bodies for rural regions
in Husum, Kiel and Lübeck (ALR 1999-2008).