Planted a crepe myrtle last September and I don't know what wrong. It had whiteflies and I took care of that. Now there is while fungus looking stuff all around the trunk. The tree is in warranty and I just don't know if it needs to be replaced or can this be treated, or is it infecting my other plants?
The white cottony substance is actually alive and it's Crape Myrtle Scale.
It destroys the bark of the Crape Myrtle in a short amount of time.
Black Sooty Mold generally accompanies this infestation.
These insects don't seem to kill the tree but weaken it and cause lack of blooming.
I would treat with Neem OIl and repeat treatment throughout the summer.
If your tree is within a warranty window, I would seek replacement for this tree.