Many times we have been asked what trees should be replanted in
an area where trees have failed. Replacing with the same species
that has died out is not a good idea unless you can identify why
your trees that you are replacing failed. Colorado spruce should
be replaced them with Black Hills spruce or Norway Spruce. The
clump white birches that are failing are likely being attacked
by borers, which are nearly impossibe to control once
established. If you can locate a certified arborist, you might
want to have the trees treated to prevent destruction.
In our area many landscapes are hard hit by bagworms. If you
are replacing stock that is destroyed by bagworms, make sure
host trees that also are infected are treated. Then replant the
same type of tree or plant. The only pests that I really worry
about are bagworms. CHECK YOUR ORNAMENTAL SHRUBS FOR BAGWORMS.
These can defoliate your nursery stock. June is time to start
looking. It's time to inspect junipers, arborvitae and pines
... even broadleaf shrubs and trees like rose, sycamore,
willow, beech, maple, elm and black locust.
The bagworm gets its name from its spindle-shaped bag that the
caterpillar carries around as it feeds on your plants.
The bag is woven from silk and is covered with bits and pieces
of leaves and twigs from the your plant. The bag of a worm
feeding on juniper will not look the same as the bag of a worm
feeding on willow. Ultimate size will be slightly over one innh
and hang down on the plant.
The larva itself is dark brown with a yellow head and yellow and
black spots on the body. You will have a tough time opening up
the bag to see it. Adult females are wingless and lack usuable
legs, eyes and antennae. They are almost maggot-like, and seldom
seen. Adult males are typical moths, black and densely hairy.
Wings are nearly clear with a span of about an inch. I have
never seen one in our nurseries only in pictures. The problem
with bagworms is that they defoliate them. Heavy populations
kill will an ornamental arborvitae and juniper. But control is
possible.
The larvae hatch from overwintering eggs in the spring usually
in May. Each larvae spins a silken bag that it carries about
while it feeds on the plants foliage. As it inlarges, the larva
enlarges the bag as it keeps adding bits of foliage as
camouflage. Many people don't know that the bag is there because
it looks like a seed pod on shrub or tree.
Because the larval stage is the only mobile stage, one bush can
have a high population and another one several feet away can be
free of bagworms. Several parasites feed on bagworms. Birds eat
them and the worms can be killed by low winter temperatures.
A very effective control is to pick the bags off the host plant
in the winter.
Young bagworms are especially sensitive to the bacterium
Bacillus thuringiensis. This is commercially available under the
trade name Dipel.
The disease caused by the bacterium affects only the moth larvae
and is very safe to use. Always read and follow label directions
before treatment. Best results will be obtained when spraying in
late afternoon or early evening.
Treat early when you first notice the bagworms, since small
larvae are easier to kill. Other insecticides which will control
bagworms include acephate (Orthene) and carbaryl (Sevin). There
are some mites, midges and bettles that can be problematic.
Rusts, make the tree unsightly don't harm this tree but can
effect other plants such as pines and apple trees. If you are
looking for a hardy, native evergreen, for a constrution or
landscape site that needs little care, this is your tree. We
have plenty of seedlings and B&B trees upto 6' ready for your
pickup. Its best to call in advance if you want more than 10 as
we will dig them fresh for you. You can visit our web site at
http://www.zone5trees.com or
http://www.seedlingsrus.com 
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