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Bagworms, leafhoppers and trees

By John Fulton          Send a link to a friend

[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.

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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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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