Agriculture Reference
In-Depth Information
Importance
Powdery mildew can cause fruit blemish in
susceptible cultivars. This disease has the potential
to cause serious damage when infected runners are
not appropriately sprayed before a powdery mildew
event occurs. High-humidity conditions favour disease
development.
Management
Use a recommended fungicide program.
Plant runners that are free from powdery mildew.
Between seasons, remove unwanted plants to break the
life cycle.
Watch for powdery mildew when humidity is high.
Fig 18.26 Powdery mildew symptoms on a strawberry, compared
with a healthy fruit (left).
PHOMOPSIS LEAF BLIGHT
AND FRUIT ROT
Cause
The fungus Phomopsis obscurans .
Symptoms
The disease usually begins with one to six nearly circular,
reddish-purple spots on a leaf let. These spots gradually
enlarge (up to 15 mm in diameter), and divide into distinct
zones. The central zone is dark brown; the next a lighter
brown; then an outer purplish zone blends into the normal
green of the leaf. Spots are oval or triangular, and may form
a V-shaped area that extends from a large vein to the edge of
the leaf. Small, black, fruiting bodies (pycnidia) may appear
Fig 18.24 Powdery mildew on strawberry leaves. Note the white
mycelium and leaf curl symptoms.
Fig 18.25 Powdery mildew symptoms on the upper and lower
surfaces of strawberry leaves.
Fig 18.27 Phomopsis leaf blight symptoms can be similar
to Gnomonia leaf blotch.
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