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

winery@lopezislandvineyards.com

Copyright 2010 Brent Charnley