Powdery Mildew of Wheat
Erysiphe graminis f.sp. tritici
Cream to white powdery spores on the top of the leaves and stems that are sometimes surrounded by a yellow to brown halo. Yellow to brown patches appear on the back of the leaves opposite the spores. The infected area turns a dull grey with a yellow brown margin with age and may have spherical black fruiting bodies.
Species Affected:Wheat, Cereal Rye.
Biology:More common in humid conditions caused by the weather or density of the crop.
More common in high nitrogen conditions and with dense crops.
Requires 85-100% humidity for infection.
Disease progression is fastest when temperatures are 15-200C
Attack all parts of the plant above ground.
Survives over summer on volunteer Wheat plants or on crop residues.
Spores from fruiting bodies on residues and powdery spores from growing plants are spread by wind.
Life Cycle:Origin and History:
Usually fairly evenly distributed through the crop.
Significance:Rarely causes economic damage.
Monitor until late in the season as mildew can infect flowering heads causing yield losses.
Management and Control:Avoid very susceptible varieties. Some varieties are partially resistant but the disease is rarely sufficiently important to warrant growing them. Use resistant varieties if persistent problems occur.
Seed treatments control early infections but are rarely profitable.
Apply in furrow fungicides or post emergence triazole or strobilurin fungicides.
Apply strobilurin fungicides early before disease development.
Related and Similar Species:Powdery Mildew of Barley (Erysiphe graminis f.sp. hordei)
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