Late last summer, my wife and I planted a row of arbor vitae. They did fine in the winter and have been doing OK until recently. The past two weeks, the leaves on many of them have turned a pale yellow green and have a very dry, crumbly texture. The soil is very moist after a wet spring here in the northeast, so we don't think it's lack of water. (Can it be too much water?) It's a pretty sunny site. We did plant fertilizer spikes about three feet uphill from them, and are wondering if maybe too much fertilizer may have gotten to the trees. We dug up a few of the spikes, and they're down to their last inch or so after only three weeks. The arbor vitae are about 4 feet tall. We're desperate to save these; any suggestions? We live five miles from the coast, about 20 miles north of Boston (Zone 5 or 6, depending on whose map you use).