About 17 days after seeding, colonies of powdery mildew appeared in the leaves
of the 0 and 5 ppm Si02-fed plants and developed vigorously, while in the 50 and 100
ppm Si02-fed plants they were depressed markedly; very few colonies appeared in the
50 ppm Si02-fed plants and hardly any in the 100 ppm Si02-fed plants (Photo 5).
As shown in Table 10, the silicon content in dry leaves increased proportionally
to the increasing concentration of silicon in the culture solution, and the colonies of
powdery mildew decreased.