est of soil suppressiveness
Of the 1800 wheat seeds planted in the experiment, 164 seeds
did not germinate at all or grew less than 5 mm from the seed
without reaching the soil surface and were not measured. The fresh
weight was recorded for 1636 seedlings. The backward-selected
ANOVA model of the suppressiveness assay included row, position,
site, sterilization, P. ultimum inoculum, row*position, site*sterilization,
and site*sterilization*P. ultimum inoculum (Table 2).
Six out of 10 farm soils had suppressive effects on P. ultimum
disease symptoms (no statistical difference between unsterilized
inoculated and control treatments for at least one soil treatment).
Crop conventional 1 and 2, Crop organic 1 and the Pasture, had no
significant differences between inoculated and control treatments
for sterilized and unsterilized soil, indicating suppressiveness
unrelated to the soil biota (Fig. 1 and Table 3). Apple conventional 2
and Apple organic 1 had no significant differences between
inoculated and control treatments in unsterilized soil, but
significant differences between inoculated and control treatment
in sterilized soil, indicating suppressiveness due to the effect of soil
biota. Crop organic 2 had significant differences between
inoculated and control treatments for sterilized and unsterilized
soil, indicating an abiotically conducive soil. Apple conventional 1,
Apple organic 2 and the Strip tillage site had significant differences
between inoculated and control treatment in the unsterilized soil
but not the sterilized soil, indicating biotic conduciveness.