You are here

Oak trees targeted by voracious caterpillars

A new year is upon us and already landscape and garden enthusiasts are anticipating the coming spring! Here are some recent questions I received from readers of this column.

QUESTION: ”My 10 year old oak tree has lost almost all of the leaves. I discovered a lot of caterpillars. I have hardly any leaves left. I have gotten rid of the caterpillars, but my tree looks very barren. Will it come back or is there something special I should do ?” – Jeanette Stevens

ANSWER: Caterpillars can be frustrating! In some cases, caterpillars can totally defoliate a tree. According to an online article published by the Extension Service of Texas A&M, when a tree is defoliated it can become stressed and serious damage can occur. Green leaves manufacture energy that allows the tree to grow and maintain its natural vigor. Once a tree is defoliated, it essentially stops manufacturing sugar which slows tree growth.

Moreover, stressed trees are susceptible to attack from various diseases and wood-boring insects. What to do? Well, caterpillar populations are generally cyclic and they rarely appear year after year, so you could simply do nothing and see if the tree comes back next spring. If you see evidence of leaf-roller infestation at that time, you could spray the leaves with a carbaryl product such as Sevin or any similar product designated for the control of caterpillars or oak worms.

To find out more about caterpillars and how to control them, I suggest you read the entire article at .

QUESTION: “I purchased 2 Grace Smoke Trees and planted them in early spring this year. Both plants are close to 5 ft. tall. They are healthy and leafed out well in the spring. I am wondering if I should prune them back a bit in the spring to help them bush out more, and...if so, how much should I prune? One plant has a v-shape trunk (with 2 main stalks) at the base and the other plant is one long trunk. Neither tree has any limbs yet. One more question: should I fertilize and when is the best time for these trees? Hope you can help and thanks so much for your advice.” – Trish Joyner

ANSWER: Pruning these plants now (or at any time during fall/winter) will promote a more intense foliage color. Also, they do flower better on new growth. Treat them the same way you would crape myrtles. Cut them back anywhere from one third to one half of the plant. It will force more branching and all of this new growth will produce more flowers and striking foliage. The rule of thumb on fertilizing deciduous trees and shrubs is to wait for them to leaf out in spring before applying your first round of fertilizer and be sure to follow the directions on the package to not overdo it. I prefer the granular fertilizer, but that’s just a personal choice. Adding compost or other natural products to the soil around the immediate base of plants can give them as much of a boost as fertilizer can. Natural products will not harm the plants and will only help to build your soil.

QUESTION: “Can I put my lawn clippings such as leaves and grass directly into my garden to till in in the spring or would this be more of a problem later?” – Neal Goble

ANSWER: It is far better to compost them first. Among the many reasons, composting the clipping first will eliminate most of the weed seed before you put it in your garden. Go to my Web site and find two recent Plant Man columns that include a lot of information on composting.

QUESTION: “I have an arborvitae in a large container, will it survive in a container over winter?” – Adrianne

ANSWER: No, You should either bury the container in the soil so that it can be insulated or take out of the container and plant.