Page 44 - Grapevine NovDec 2021

Around The Vineyard

Take Care of

Late-Season

Powdery &

Downy Mildew

After Harvest

By: Annie Klodd, University of Minnesota Extension
A have a few things to check off the to-do
fter grape harvest, grape growers still

list before putting away the sprayer. These
include late-season fungicides, weed management,
fertilizer application if needed, and winterizing the
sprayer.

Snuffing out active, late season powdery mildew
and downy mildew infections can make a big dif-
ference for grapevine health as the vines senesce
for winter. Severe infections reduce photosynthesis
and defoliate vines pre-maturely, increasing the risk
of winter damage to the vines.

In fact, mild fall temperatures are perfect breed-
ing ground for these diseases, which thrive in tem-
peratures in the mid-50s to mid-70s.

Consider control measures to prevent early leaf
drop and help vines properly acclimate for winter.

Powdery mildew on the upper side of a grape-
vine leaf (left) and downy mildew spores on the
underside of a leaf (right). Matt Clark, University
of Minnesota.
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