Several of my Japonica varieties, though they have buds and/or flowers, are looking as if they are not in good health. Many twigs (not entire branches) produced no leaf growth last summer and now appear dead, but the remaining twigs do have new leaf and flower buds. The overall effect is of a very sparsely foliaged plant with an airy, open structure (a great pruning goal, if it had been intentional). These plants tend to be in more shade than some of the others, but that's the only variable I can find. Perhaps the plants are just refusing to produce more leaf growth than the available light can support?

I'm a fairly experienced grower, but this has me scratching my head. It's not winter damage (lots of flower and bud damage this year due to early bloom during our "January thaw"), since this condition began to appear during the last growing season. I see no evidence of tea scale (which has been a problem in other years) or phytophthera (sp?) root issues (another problem given my drainage problems). Any thoughts?