Vascular diseases of trees; raising pumpkins
By John
Fulton
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[May
16, 2013]
Many major tree diseases cause
vascular system blockage. Verticillium wilt, oak wilt and most of
the canker diseases fall into the group. Usually a fungus "plugs the
pipes" so there is reduced movement of water up and food down. This
leads to dead areas above the blockage. Of course, if the blockage
is on the main trunk, you end up with a dead tree.
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It is often possible to see streaking of the wood, or a dark
ring around the center portion of the branch or trunk with
verticillium wilt, but a lab analysis is needed for definite
confirmation. There are no cures for any of these diseases at
this time. It is recommended to remove and destroy trees
severely infected with verticillium, to help prevent transfer
from root grafting.
The list of trees affected by verticillium is very large, but
good-quality maples are very susceptible. There have been many
affected trees this year, including maples and ashes.
The only treatment is to water and fertilize to try to get
new growth and new water- and food-carrying tissues.
We have really had 20-plus years of stressful weather. Just
like us, trees like moderate weather. When we have extreme heat
and cold, and no moisture or a flood, the trees are stressed.
This makes them more susceptible to factors that are always in
the environment. Try to even out some of the extremes by
watering when it is dry, fertilizing when you do the lawn (or
just fertilize the tree) and mulching to even out the soil
temperature in the root area. Remember that many diseases can be
passed with pruning equipment, so disinfect your equipment
between cuts.
Pumpkins
Many pumpkins are being planted about this time. While this
practice is great for producing pumpkins for pumpkin pie, it
really doesn't work very well for producing the Halloween
jack-o'-lantern pumpkins. The Halloween pumpkins are best
planted around Father's Day. This timing helps prevent the
pumpkins from rotting before we get to the end of October.
Many different pumpkin varieties are available, and they come
in many sizes and shapes.
The small pumpkins, ranging from 2 to 5 pounds, are called
pie types. They are normally used for cooking and fall
decorations, and include the Baby Bear variety.
Intermediate and large varieties are
primarily used for jack-o'-lanterns. Many of the newer varieties
have stronger side walls to aid in display and carving. The
flesh of these varieties is generally poor in quality and not
used for cooking.
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Processing pumpkins, which are canned commercially, make poor
carving pumpkins and are more like a buff-colored watermelon in
appearance.
The jumbo or mammoth varieties are mainly used for exhibition.
These jumbos can weigh in the 900-pound range. For most homeowners,
you might want to pass on these since moving a 900-pound pumpkin
isn't for everyone. The other option is to try to grow one in place.
Vining pumpkins need at least 50-100 feet per hill, with the
larger pumpkins requiring the larger area. Hills should be 5 to 6
feet apart, and rows of hills should be 10-15 feet apart. Each hill
should have about four seeds per hill, planted about an inch deep.
The miniature varieties such as the Jack-Be-Little are sometimes
grown in rows with seeds planted every 8 to 12 inches, then thinned
to about 2 feet apart in the rows.
Keep the pumpkin bed free from weeds by shallow hoeing, and make
sure it is watered during extended dry periods. Major pests are
squash bugs, cucumber beetles and vine borers. Most often, frequent
applications of an insecticide such as carbaryl will help protect
the new runners from the vine borers and also control the beetles
that transmit the wilt virus. Apply insecticides in late afternoon
or early evening to make sure no applications are made to open
blooms that attract the bees for pollination.
Fall decoration pumpkins should be cut from the vine before the
vine dries in order to have a good stem attached to the pumpkin, but
after the color is acceptable.
[By
JOHN FULTON,
University of Illinois Extension]
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