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Grape Vine Diseases
in Western WA
Organisms and their organic control
Powdery Mildew
Botrytis cinerea
Powdery Mildew Uncinula necator
Life Cycle & Infection: Over-wintering spores in
bark & bud scales (cleistothecia) or as mycelium in bud scales-shows up as ‘flag shoots’ in early spring.
Conidia spread by wind to vulnerable young tissue.
Growth occurs when temperatures above 50 F occur.
Puget Sound climate perfect for disease all summer long.
Powdery Mildew Identification
Botrytis Cinerea aka Grey Rot
Life Cycle & Infection: Sclerotia spores over-
winter on mummified berries and in environment (blackberries)
Infection occurs during flowering.
Infection needs free moisture for 24 hrs with temps between 50 – 82 F.
Disease enters berry through injury from wasps, machinery, powdery mildew.
Botrytis identification
Over wintering Botrytis mummies.
Photo by Jack Kelly Clark.
Botrytis infected shoot tip.
Photo by Jack Kelly Clark.
Botrytis identification
Bunch Rot Complex of Botrytis
and Penicillium moldsPhotos by Jack Kelly Clark
Controlling Powdery Mildew
Monitoring Procedures
Computer warnings based on UC Davis
model - Avatel or other monitor
Visual observations
Flag shoots in spring
Mildew on other plants- roses, wild blackberries
Disease Control
for Powdery mildew & Botrytis
Organic Control
depends on
prevention
Resistant varieties-
hybrids, Regent
Air circulation and UV
light
Trellis design & shoot
positioning
Vertical Shoot Position
Leaf removal
Disease Control
for Powdery mildew & Botrytis
Organic fungicides prevent
infection: sulfur, Copper
hydroxide, stylet oil, and
biological agents- serenade,
sonata, & actinovate.
Organic Eradicates are now
available: Potassium
bicarbonate, Oxidate, and
insect soap M-Pede
Sprayer must get even and
complete coverage while
penetrating dense canopies
OSU & OVS have great
suggested spray programs.
Spray Program Timing
Patricia A. Skinkis, © Oregon State University.
Disease Control Take
Home:
Cultural controls the most important: site
selection, varietal choice, trellising, fruit
thinning, vigor and canopy management.
Timing of spray program critical:
preventative actions reap big harvests!
Early control of PM & every 10 days.
Bloom spray and preventatives for Botrytis
Be vigilant! Get Help if needed.
Presented by Brent Charnley
Consultation Services available
Site evaluations and advice
Viticulture techniques for Puget Sound
Winemaking expertise and assistance
Contact: 360-468-3073
Copyright 2010 Brent Charnley