I have 3 river birches planted 6-1/2 yrs ago just before we bought (new construction). Each has matured as near perfect 3 trunk clumps. They were planted in the usual (though not optimal) heap of mulch (5 ft diam) otherwise surrounded by very dense fescue grass. I have fertilized and re-mulched them every Spring since then. They have gotten much taller than my neighbors' river birches planted at the same time and are perhaps 25 ft now. Since the beginning, I've noted heavy yellowing and loss of leaves starting as early as mid-June. During the second rather dry Summer, there was considerable loss of leaves and resultant branch die-off by Aug. I bought TreeGators the following year and continue to use them.
I'm a doting tree-lover and endlessly on the lookout for leaf die-off. I constantly compare my river birches with a large number of neighborhood betula negras all planted at the same time under the same conditions (mulch mounds, dense fescue yards etc). I'm the only nut-case who obsesses over mine with the watering bit and the fertilizing. Even so, only mine seem to experience the yellowing and the die-off to such a significant extent. One week without rain or Treegator irrigation and bam! Mine only. I might add that the surrounding fescue is always watered too all Summer long - and as a result doesn't go dormant. Also, I note that while my birches are tallest, they have remained quite narrow without the fuller spread of neighboring birches. Many of my branches seem to bow back towards the ground whereas neighboring trees are fuller and reach for the sky. I frustratingly note that those neighborhood birches that are under the most dire neglect/dirth of pampering still seem to lose fewer leaves under heat stress - and have a fuller spread than my much taller trees. What - if anything - gives?!?
Am I spoiling them by not allowing them to figure it all out without my over-parenting?