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Bagworms, leafhoppers and trees
By John
Fulton
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[JULY
15, 2004]
Bagworm
pressure has been very heavy this year, even on species that aren't
normally attacked in great numbers. Crab apple, grapes and oaks have
had large numbers of bagworms in some areas of the county. This is a
reminder to check different trees and shrubs for bagworms.
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At this advanced stage, the
best material to use is B.t. It is commonly sold as Dipel or
Thuricide. These products affect only the larvae of moths and
butterflies. This also means they are extremely safe to use, as
there is no potential for injury to people or pets.
Bagworms may be controlled with
B.t. until they are no longer adding green material to the bags.
Remember that the current bags contain the future egg-layers. You
can also pick off bags to keep the 2005 crop from being present.
Many people ask: How long can I
control bagworms? The answer is rather simple. If there is still
green material being added to the bags, there is still time to
control them. The B.t. products are probably the only ones to
consider as we hit mid-July.
Potato leafhopper
The potato leafhopper is one of
the more inconspicuous insects that cause damage. They can damage
anything from potatoes to maple trees and everything in between. The
leafhopper is a small, wedge-shaped green insect that sucks plant
sap. The main problem they cause is injecting a toxin back into the
plant when they finish sucking sap.
Damage from the leafhopper
appears first as yellow "V"-shapes at the tip of the leaf. As the
damage is older, the "V" turns brown or black. With wind and rain
tattering the leaf, the dead material then falls off, making it look
like the tip of the leaf is missing.
Control can be accomplished by
spraying with Sevin, permethrin, Orthene, Cygon and many other
products. Controlling leafhoppers takes persistence. In heavy years,
potatoes may have to be sprayed every three to four days. The toxin
from these insects is very potent. In alfalfa fields, it is
recommended to spray foot-tall alfalfa that has one leafhopper in
about three square feet.
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this article]
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Tree problems
The red maple, Acer rubrum, has
been the most planted tree over the past several years. This year it
is showing some signs of hardship in certain areas. Symptoms include
small red leaves at the tips of branches, stunted growth or death of
portions of the tree.
Probably the first thing to
check for is potato leafhopper damage. It is probably the simplest
thing to check for and take care of. Maples have a lot of sap
flowing in them and are favorite targets for leafhoppers. Red maples
can also have problems with high pH soils, that is, soil with lots
of lime added or naturally high in pH. Another possible cause is
verticillium wilt. This would be the worst of the possibilities,
since there is no "cure" for this disease. Verticillium plugs up the
tissues in the tree, making them unable to carry water or food. The
only "treatment" is to fertilize and water and try to add new
material to the tree, if it has not lost its landscape value due to
dead wood.
Ash
trees are also showing some signs of trouble. Ash yellows and
anthracnose are the two most common problems. The ash yellows
disease is caused by a mycoplasma-type organism and causes sparse
foliage. A similar problem, ash decline, has not had a cause
associated with it. There are no cures for the ash problems listed,
so keep those trees growing as well as possible.
[John
Fulton,
Logan County Extension office]
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