Question
 Hey Jim,  I have a tree form crape and its about 3 yrs. old. I prune it every year like one should. I fertilize it with triple 16 before it starts to green out. This year its leaves have dots that turn into holes. Can not find any leafminer or any other insect. I hope it is not a virus!!!! Help....   thanks  Mike

Answer
Sounds like a disease called a leaf spot.
Cercospora Leaf Spot: Leaf spots may appear on crape myrtle that are caused by the fungus Cercospora species during periods of warm, moist weather. Yellow spots (1/8 to ?inch diameter) appear on the upper leaf surface with white-grey sporulation of the fungus on the lower leaf surface. The disease can result in almost complete defoliation of the plant in late summer and fall in susceptible cultivars.

Prevention and Treatment: Provide good air circulation and avoid overcrowding plants. If disease is severe enough to warrant using chemicals for control, thiophanate-methyl (Ferti-loame Halt Systemic Fungicide or Green Light Systemic Fungicide) will control Cercospora leaf spot. Apply all fungicides according to directions indicated on the label
Check with your local nursery for these fungicides.