Question: I am confused about how to prune crape myrtles based on what I see around town. Is there a correct way to prune these trees?
Answer: Based on what I see, not many owners seem to know either. There are crape myrtle trees pruned correctly — then there are those that are "crape murdered" each winter. Crape murder means cut in half or lower. The fact that this plant is a tree and not a shrub should tell you pruning them every year is often not needed. Those trees that are pruned hard every year are either because they should have never been planted there in the first place or they were pruned by someone that does not know any better. The practice of cutting them back each year is so prevalent that it is no wonder we have developed the mindset that it becomes the proper pruning practice. Once they are pruned back, hundreds of new sprouts emerge each spring below the cuts, turning the tree into a bush-like plant. Therefore, it must be repeated again the next year to suppress the excess growth. The cycle of yearly pruning has begun. To restore these murdered trees to 3 to 5 nicely spaced trunks requires selective pruning and patience. The excess sprouts are removed in the summer months for several years in order to develop a new trunk structure. That is a skill set few people have or are willing to pay for. If crape myrtles died from this type of butchery then it would stop and the owners would learn the more appropriate pruning techniques. If you want to learn the correct way to prune, I suggest searching the Internet for "Pruning Crapemyrtles-Clemson University." Crape myrtles add a lot of beauty to our community, but they should be planted where they have room to grow and mature. They are often not the best tree for streets, parking lots, and shopping centers, where space is limited and sight lines obscured.
Question: The leaves on our Knockout roses are wilted and look dead. Did the cold winter temperatures kill them?
Answer: Knockout roses are semi-deciduous plants. Therefore, they will retain many of their summer leaves during the winter. Single-digit temperatures destroyed many of the remaining leaves but not the plant. Your roses are fine. They mayl need pruning if you want to keep them from growing too large. Near the end of February you can safely reduce their height to around 2 feet from the ground. Thin out the growth, leaving 4-6 strong and large branches. This type of pruning will allow you to keep this plant at a height of 4-5 feet during the summer. Young plants that were planted in the last 2 years may not need pruning at all. Roses are fertilized in mid-March.
Question: I have heard there is an insect that is killing crape myrtle trees. Is this true?
Answer: Yes, there is a new pest appearing on the horizon for crape myrtles and it is in North Carolina. Fortunately, it does not kill the tree. The pest is an insect called the Crape Myrtle Bark Scale. Its presence can be identified by the appearance of sooty mold. Sooty mold is black fungus that grows on their excretions. The leaves of the infested crape myrtles will turn black, as does every shrub and patio under its canopy. Another insect called the crape myrtle aphid will do the same. Close examination by someone that knows their insects can tell them apart. As their populations increase, your crape myrtles will turn black and ugly due to sooty mold. They will stop blooming too. Insecticidal treatments will be needed each and every year to keep this insect under control. With literally thousands of these trees planted in yards, parking lots and along our streets, it will become a headache for homeowners and governments alike. Most trees will never be treated. A ray of hope is that some of our ladybug species will adapt to this new pest and begin feasting on them. Hopefully these ladybugs will spend less time trying to get into my house. So for now, we must wait and watch for when they appear here. I will let you know.
TREE SEEDLING SALE
The Alamance Soil and Water Conservation agency is selling tree seedlings in small amounts. This year you can get 25 loblolly pine trees for $5 and 20 Eastern red cedars for $10. Plant these trees as soon as you get them. They make great screens, borders, or use them to fill in areas you no longer want to mow. Place your order by calling 336-228-1753, ext. 3.
Rett Davis is a retired Alamance County Extension Director and certified arborist. You can email your questions to him at Rett_Davis@ncsu.edu