We have 6 of the myrtles (3 on each side of the driveway), not all the same variety. We have noticed a curious "sap" falling on the cars this year that we have never had before. Now the leaves on some are yellowing and falling off. What could be causing this?
Why Are the Leaves on Our Crepe Myrtle Turning Yellow and Falling Off?
Certified GKH Gardening Expert
Crepe myrtles normally don't drop sap, so this is likely honeydew from a pest infestation. The most common is aphids. I would treat the tree with neem oil. This will kill the pests without harming people, pets or beneficial bugs. Here is more information: