Crape Myrtle Growth Problems
We have two crape myrtles, almost two years old. One is flourishing, with leaves and blooms until recently on top and on the lower branches. But the second one has lost the leaves on top (for about a month), even though the new branches (or suckers ?) on the bottom are doing great. We need to know if this is OK or if we should cut back the lower branches or some of them to make sure there is adequate growth on top in the spring. What could have caused the "denuding" of the upper branches, and is there something we should be doing about that? Also, should we fertilize these trees before winter?
Early coloration and leaf drop are a sign of stress.
It seems from your past questions that you have had concerns about the second crapemyrtle for some time.
Any parts of the plant that are dead (brittle, snap easily and did not leaf out well in spring) can be pruned out at any time. The main trunk could be dead or dying if it was planted or mulched too deeply or for other reasons that were covered in previous responses. Leave the new healthy branches at the bottom. They are the source of new growth from the roots. Many crape myrtles grow as multi-stemmed trees/shrubs, and over time it is from these shoots that will become the main scaffold for your tree. Crapemyrtles tend to have difficulties with our winters here and in a harsh one can be killed back to the ground each year, so that is another possibility. The good news is that these plants bloom on new wood that is made each year.
Since these trees are young, you could fertilize them (granular) after leaves have dropped from deciduous trees. Fertilizer is not medicine though. If there is a root or planting problem with that particular tree, it will not solve it.
Check to make sure that you can see the widening of the trunk as they enter the ground, and pull back mulch from contact with the base. If mulch is deeper than 2-3 inches, remove the excess.