Crape Myrtle leaf drop
I have a Velma's Royal Delight crape myrtle that I planted in 2008. It is about 12 feet tall. It has bloomed nicely for the past several years, but this summer, I noticed that there is significant leaf drop going on (leaves turn spotty yellow, fall off tree, then quickly turn brown...PIX ATTACHED) along with less-than-robust blooms. Since it has been very hot, I thought that it might need water. I have been deep watering it every few days for the past week (might be too late for that), but I am now wondering if it has a disease. My question is, is there a way to treat it, or should I cut it down? I also have several other crape myrtle varieties in my yard and they are all healthy. If the above tree tree has a disease, are the others susceptible?
We think that there may be more than one issue going on here.
Crapemyrtles in general are susceptible to powdery mildew, and fungal diseases like Cercospora. It does look like you have a leaf spot disease, but they are not usually a great threat to the plant. Here is our page about fungal leaf spots on shrubs:
Often managements techniques like sanitation (clean up) of diseased leaves and trying to increase light and air circulation to the plants so leaves dry quicker helps with control.
Other crapemyrtles could be infected, but they may be in better site conditions.
We wonder about the i.d. of your plant, because that particular variety is supposed to be disease resistant, and in general smaller than yours.
As far as the height of yours and the sparse blooming, that can happen when they are not grown in full sun. How much sun a day does the area get?
You shouldn't need to remove the shrubs and they can be deeply pruned in the spring which should also make them more attractive for how close they are planted next to your house. (Crapemyrtles in general do not need heavy pruning each year if planted where their size is o.k.)
Here is our pruning information: https://extension.umd.edu/hgic/topics/pruning-tree-and-shrub-basics