Why do my crepe myrtles look like they are raining ?
Every late afternoon and early evening as I sit looking out at my trees it starts to look as if if there is a heavy sprinkle outside , but we have discovered that it is all coming from our two crepe myrtles. It only started in the last couple of weeks as far as I know . We were wondering is this normal ? Is it okay ? Is there something that we should be doing ? Thank you for your help .
The rain falling from your crepe myrtles is called honeydew in polite circles, but it is actually insect excrement, probably from the crepe myrtle aphid, but also possibly from the crepe myrtle bark scale. On the positive side, they are both host specific pests so they won't move to your other plants. Both are food for beneficial insects especially ladybugs. You can choose to wait and see if the beneficial insects come in and bring the pest population down.
On the other hand, honeydew is a real nuisance when it falls on your car or patio furniture. Black sooty mold will eventually grow on the honeydew and that interferes with the plant's ability to photosynthesize and make food for itself. Sooty mold is also rather unattractive. You can control both pest options with soil applied insecticides such as imidacloprid or dinotefuran, or even a really strong spray of water (you'll probably have to repeat this regularly.)