Why are yellow leaves starting to show up on my Crape Myrtle?

Yellow leaves can be symptoms of many things.  Some of which are too much water, not enough water, irregular watering, changes in the weather, pests, mechanical damage, lack of sufficient nutrients, or the plant may be starting to go dormant earlier than usual.  Without knowing the specific cultural practices that the homeowner has been doing, it’s difficult to give a simple answer.  In most cases, the cause has been water.  Think about the weather we’ve been having this summer.  We have had a combination of both excessively wet and dry periods.  These irregularities could easily cause this symptom.  Typically when a plant is overwatered or is planted in an area of poor drainage, lower leaves will turn various shades of yellow/green or yellow, then drop off.  When irregular watering occurs, leaves will often turn yellow or red depending on the crape myrtle variety.  Sometimes a brown border will form around the leaf edge, later progressing to totally brown leaves, which may or may not drop.  If a plant retains these brown leaves, that usually means that portions of that plant are dying.  Should this be happening to you, carefully check your plant and review what you’ve been doing/not doing to it for the past 2-3 months.  Do you see where any mechanical damage to the bark may have occurred; either with insects feeding, a weed eater, etc.?  Is the injury sufficient to cause the leaves to change color?  If not, review your cultural practices.  Good luck with your diagnosis.