Four yr old smoke tree, pruned in early march, has continued to develop beautifully, but now its leaves are yellowing and dropping at an alarming rate. Still has new growth but also has some small amount of dead/dying leaves. This is occurring mostly on inner limbs.
The leaves can fall off your smoke tree for several reasons:
too much, or too little water
insect or disease damage
damage to plant by weed-eaters or mowers
age of tree
too acidic soil