November - Oregon State University Extension Service

Hot-line Hot Topics
Caller wanted to know if it’s too late to plant
kale. No, they will overwinter.
Caller has 8 plants of white and blue grapes,
and plants are 7 – 8 years old. The plants were
pruned in winter and again during summer.
There is no insect activity. Grapes were watered
once in June but not again during the
summer. The leaves are white. The fruit set
well, but over the last 4 weeks has become
shriveled and desiccated. This disease is botrytis
and is common west of the Cascades. It’s
especially common during wet weather close to
harvest when the leaves are dense and grapes
are accumulating sugar. Compact grape bunches
are more at risk for this disease. Cultural
controls are to remove east and north leaves
(removing others may cause sunburn) that are
close to grape bunches. This helps with spray
penetration and coverage. Use trellises for aeration
and sun and avoid too much vegetative
growth. You should also manage powdery mildew,
as this can contribute to the disease. For
chemical control, spray at the end of bloom or
beginning of fruit set. Continue to spray at various
stages of growth. Some of the chemicals
specified in the PNW Plant Disease Handbook
are Botran and Captan. The white on the grape
leaves is caused by powdery mildew, which
can be treated with sulfur.
Caller wanted to know how to make a fruit fly
trap. Use vinegar or fermented liquid in a dish
with a few drops of dish soap to release water
tension.
Caller wanted to know if sweet peas seeds will
mature if plants are pulled now. No, they
won’t. We suggested they cover the plants and
hope the seeds mature on the vine.
Caller had a young apple tree that was underproducing.
We suggested they water it more in
the summer and prune for more vigor.
Caller wanted to know if Italian prunes are self
-pollinating. Yes, they are.
Sandy O’Malley, MG
A walk-in brought in maple leaves with bumpy
lumps on them. These were caused by maple
gall mites, also called bladder gall mites. Adult
mites eat newly-formed leaves in the spring.
The leaf tissue grows out and forms a gall
around each mite. When the leaves are fullsized,
each mite lays eggs and dies, leaving
hundreds of tiny nymphs inside each gall.
When the nymphs grow into adults, they leave
the gall and crawl to new leaves. This cycle
continues until late summer when leaf growth
stops. The adult mites overwinter under the
tree’s bark. These parasites are seldom harmful
to the tree.
Caller wanted to know what was causing
brown on ends of arborvitae (Thuja occidentalis).
The disease is called tip blight and is
caused by the fungus, Pestalotiopsis funerea.
The twig tips are brown or tan and may have
black fruiting bodies on them. Spores are
spread from diseased tissue by splashing rain.
Cultural controls are to protect the plants from
weather extremes such as winter cold and summer
sunburn. Chemical control is to spray in
spring and early summer with Bordeaux or
fixed-copper sprays.
Caller wanted to know where they could compost
a 500-pound pumpkin. We suggested they
go to Lane Forest Products. Local produce
stands have also given/sold them to farmers for
cattle and pig food.
Caller wanted to know how to remove a wasp
nest in the ground. Wasps and yellow jackets
don’t fly when it’s less than 45° F outside.
When the temperature is this low, you can pour
boiling water on the nest at night. Soak the entrance
hole and nest well.
My favorite:
Caller said they have rats in their compost pile
and wanted to know what to do. We suggested
they get a cat.
The Garden Gate November 2013