Page 46 - Grapevine May-June 2020
P. 46
Around The Vineyard
Managing Powdery Mildew
in the Vineyard
By: Becky Garrison
A Disease Management Handbook,” grape through bloom that can infect the vines. Once the
ccording to “The Pacific Northwest Plant
fungus becomes active on infected buds, it covers
powdery mildew represents “A fungal dis-
ease common to all areas of the Pacific Northwest. the emerging shoot with asexual spores.
The disease tends to be more severe on the west As part of the 2020 Oregon Wine Symposium
side of the Cascade Range but is a chronic problem on February 11-12, Dr. Jay W. Pscheidt, profes-
in arid districts where over-the-canopy irrigation sor and extension plant pathology specialist at
is used for early-season frost protection or water- Oregon State University, spoke about the problems
ing.” Over the winter, the fungus may lay inside managing grape powdery mildew in the vineyard.
the vine’s dormant buds as a group of thin threads Throughout this presentation, he noted that since
(hyphae) or as small black bodies (chasmothecia) powdery mildew can be difficult to manage once
located on the exfoliating bark of the vine. In the it’s become dominant in the vineyard, prevention
spring, sexual spores are released from bud break remains paramount in addressing this disease.
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