Can I control aphids on my crape myrtles this time of year?

ASK THE HORT AGENT

Question Can I control the aphids on my crape myrtles this time of year?

Answer Crape myrtle aphids were originally discovered in Hawaii. Now they are found all over the world. Since this aphid was found in Hawaii, it was given a Hawaiian scientific name - Tinocallis kahawaluokalani. If you say the last part slowly (ka-hawa-lu-o-ka-lani), then you will find your hips start to sway as if you are wearing a grass skirt.

The crape myrtle aphid only feeds on crape myrtle trees. It pierces the leaves and withdraws the tree’s sugary sap. Since the feeding aphid withdraws more sugar than it can use, it excretes a sugary substance called honeydew (not to be confused with the infamous list called “honey do”).

Large aphid populations can cover the leaves of a crape myrtle with honeydew. Airborne sooty mold spores land on the honeydew and use it as a food source. Soon the crape myrtle leaves are black from the sooty mold fungus. This relationship to sooty mold is the primary reason people want to control crape myrtle aphids.

As trees go dormant in the fall, crape myrtle aphids lay their eggs on crape myrtle stems and trunks. A wintertime application of horticultural or dormant oil will suffocate the overwintering aphid eggs. If you really want to get into the Hawaiian aphid killing spirit, then sing Mele Kalikimaka (pronounced meh-leh kah-lee-kee-mah-kah) as you spray. Go here to get the tune stuck in your head http://www.youtube.com/watch?v=hEvGKUXW0iI

If you get distracted then the next thing you know it will be spring. When this happens, it is too late for spraying oils. Systemic products can then be used with no impact on beneficial ladybugs. Orthene 75S (acephate) is an insecticide that can be painted (also called banded) onto the trunk of the crape myrtle. It will be absorbed by the tree and transported to all the leaves. No spraying is necessary, yet total control of the aphids will be achieved. Read the label for mixing and banding instructions.

Bayer also makes a product that is moved systemically throughout the tree. It is called Tree & Shrub Insect Control. Simply mix this product with water and pour it around the tree. Read the label for specific mixing instructions.

Apply the systemic products as close to bud break as possible. For more crape myrtle aphid info, go to http://www.ces.ncsu.edu/depts/ent/notes/O&T/shrubs/note31/note31.html If you don’t have internet access, then call the Extension Office at 893-7533 or email me at gpierce@harnett.org

In Hawaiian, the crape myrtle aphid’s name, Tinocallis kahawaluokalani, means “you fish on your side of the lagoon, I’ll fish on my side and no one will fish in the middle.” I think this is the Hawaiian way of saying “You work on your honey do list, I’ll work on my honey do list and we won’t bother each other.” Whose list includes elimination of the honey dew?

Mele Kalikimaka!

Gary L. Pierce

Horticulture Extension Agent