Gardening

August Q&As–Bald Cypress Knees to Stinging Caterpillars

by Dr. William M. Johnson
Galveston County Extension Agent - Horticulture

August 24, 2005

Although bald cypress trees are commonly associated with swamps and waterlogged environments, they will grow very well in well-drained soils. Unfortunately, some of our gumbo clay soils do not provide sufficient drainage to avoid production of "knees."
Photo by Herman Auer

Question: Do all bald cypress trees have knees?

Answer: "Knees" produced by bald cypress trees grown in the landscape is a symptom of over-watering and/or a soil with poor drainage. Although bald cypress trees are commonly associated with swamps and waterlogged environments, they will grow very well in well-drained soils.

Properly watered trees grown in a well-drained soil do not produce knees. Unfortunately, some of our gumbo clay soils do not provide sufficient drainage to avoid production of "knees."

Question: My family has always dusted vegetables rather than spraying them. Sometimes, unless it rains, the white dust residue will remain for weeks. How long are garden dusts effective?

Answer: Garden dusts are only effective for 5-7 days regardless of how long the actual dust particles applied remain visible. This is why it is so important to apply only a very thin–almost transparent–layer of dust when spraying.

If you pour it on, as many people do, after several applications you will have a "whitewashed" plant which can actually be damaged by the excessive accumulations. Such accumulations should be removed by washing before cooking or eating.

Question: How do I deal with all these sprouts coming up from the base of my crape myrtle trees? Can I spray something on them?

Answer: Forget using any weed killers. That will harm the overall tree. Trimming them off throughout the summer is the best way to slow them down. Prune the sprouts close to the trunk. Keep this up all summer and you will slowly win this battle.

Question: Several of my trees have low hanging branches that are in my way when I mow. Do I need to wait until winter to remove them?

Answer: Go ahead and remove the objectionable limbs. Summer pruning of small-diameter, low-hanging branches is safe. The important thing to remember is not to remove the branch collar which looks like a swollen area where the base of the limb enters the trunk. Also, make a clean cut.

I strongly recommend that all other major pruning activities be postponed until December through January while trees are in a state of dormancy. No painting of the pruned site is required or recommended.

Q: The leaves on my crape myrtles have a gray mold on them. Is this something I should be alarmed about?

A: This is one of the powdery mildew diseases and the most important disease of crape myrtles. It is the more serious in the spring and early summer. The growth of this fungus will coat the leaves causing them to be distorted and stunted. The flower buds will not open properly. Crape myrtles will vary in their resistance to this disease. You can reduce the severity of this disease by using a fungicide that is effective on powdery mildew. Effective fungicides include Immunox and Bayleton. To control this disease, make 2 to 3 applications 7-10 days apart.

Q: Is it true that some caterpillars can sting you like a hornet? If so, how do we know which ones to be on the lookout for?

A: Yes, there are several species of stinging caterpillars. However, most caterpillars are not poisonous. The stinging caterpillars have stiff poisonous hairs or spines on their bodies. The hairs or spines are connected to poison glands. When a person comes into contact with the spines, they break and venom is released.

Reaction to this venom varies from mild to severe. Small children can have severe reactions. Injury from these caterpillars is most common among children playing in yards and trees

There are several to be on the look out for. The puss or asp caterpillar is the worst. This one is covered in gray, brown or yellow hair. You cannot see the eyes or the legs. Puss caterpillars grow to about 1 inch in length, are teardrop-shaped. They resemble a tuft of cotton or fur due to their long, silky hairs.

The saddleback caterpillar is also very common. This one is very colorful and striking in appearance. It too is about 1 inch long and is pale green in color but with a purple or brown center that resembles a saddle on its back. Its sting is less severe than the puss.

The Io moth caterpillar is also around. It is about 2 inches long and pale green in color. It has a very striking set of stinging spines that would seem to say "Touch me and you’ll really regret it." However, the sting is relatively mild. These are the most common of the stinging caterpillars even though there are a few more.

Question: Is there any difference in taste or nutritive value between green peppers and those that mature and turn red?

Answer: Peppers that are allowed to mature and ripen entirely, from green to yellow or red, are higher in vitamin content, especially Vitamin A. There is little difference in taste although there is a considerable difference in texture caused by the ripening process.

Dr. Johnson is a horticulturist with the Galveston County
Extension Office of Texas Cooperative Extension, Texas A&M University. Visit his web site at http://aggie-horticulture.tamu.edu/galveston/index.htm

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