Question: Our oak tree is full of worms that are eating all the leaves off some branches. What can we do?
Answer: 'Tis the season for various defoliating caterpillars. You happen to have the orange striped oakworm. Your photos were the key to proper identification. Damage to trees is minimal at this time of the year. Our hardwood trees have already made enough food reserves for winter survival and the loss of leaves at this point is not harmful. As a rule, damage is limited to just a few limbs and not the entire tree. The exception would be a newly planted tree. In just a few days or weeks the caterpillars will leave the tree in search of a winter home. You may find them crawling across drives, roads and sidewalks in droves. They are not feeding at this point and therefore using an insecticide is pointless. If these caterpillars and their associated droppings (they resemble small peppercorns) are falling upon your outdoor eating space, you may spray any broad spectrum insecticide (sevin, bifenthrin, cyfluthrin). A blast of water from a garden hose is a good organic approach. I recommend picnicking under maples and pines at this time of the year.
Question: Wisteria vines are choking my trees and sending runners into my lawn. I have tried various weed killers that have been recommended to no avail. What is left for me to do?
Answer: Chinese wisteria is an invasive weedy vine similar to kudzu. It is tenacious, aggressive and a fast grower. The weed killers you are using are better suited for broadleaf weeds in lawns and easier to kill vines. The first approach to controlling this vine is to sever the vine at the base of the tree with a pair of loppers or brush axe. Undiluted glyphosate (Roundup or a generic) can be painted onto the cut stump surface of the vine. You can also use a brush killer that contains tricolpyr. This method is referred to as a cut stump treatment. Any regrowth can be sprayed with a diluted version of these two herbicides. Once the vine is severed, all top growth will die in the tree. Runners and ground level sprouts of wisteria should be sprayed with a 4% solution of Roundup or a generic glyphosate at this time of the year. Late summer is the best time to maximize control. Regardless of the Roundup concentration you buy, read the label for the mixing instructions for a 4% solution. It is more economical to purchase products that contain from 41%-48% glyphosate as the ingredient.
Question: Several areas in my pachysandra bed have died. What is causing this?
Answer: This ground cover is subject to stem blights that can occur during wet periods or from being overly irrigated. This fungus is fueled by a buildup of organic matter from fallen trees leaves that have accumulated in the plant bed. All the above leads to increased moisture and dampness that encourages the growth of this fungus. Your beds need to be vigorously raked to remove all tree leaves to encourage drying and air movement. This winter it may be beneficial to renovate the bed by mowing off the tops and raking out all loose and dead stems and tree leaves. New growth will reappear in a matter of weeks. You can transplant new clumps of pachysandra back into those dead areas at any time.
The Buster Sykes Demonstration Farm will be open to the public this Saturday, Aug. 18 from 9-11 am. It is located at 2430 Turner Road in Mebane. This is a wonderful opportunity to see the latest varieties, pruning and training methods, and production practices for both small fruits and tree fruits adapted for growing in our area of the state. Mark Danieley, Alamance County Extension Director and horticulturist, will be there to answer your questions. Take advantage of this opportunity to actually see these practices and interact with professionals. The Buster Sykes Demonstration is a 180-acre gift to N.C. State University from the late Buster Sykes of Mebane.
Rett Davis is a retired Alamance County Extension Director and certified arborist. You can email your questions or submit plant related photos to Rett_Davis@ncsu.edu