Question: I planted four apple trees last fall in Katy, Texas. Two of the trees died recently, one looks like it is on its way out and the other is still hanging in there. The growth has been pretty minimal, I've gotten maybe 3 inches of limb growth on all the apple trees. I pulled up the two dead trees yesterday to examine the roots. I looked up the symptoms of Cotton Root Rot, but can't say that what I am seeing on these trees is consistent. One of the trees has some sort of green fungus growing on it, similar to what I've seen on decaying Iris rhizomes and the root growth doesn't look stellar. The other tree did not have any visible fungus on it and had a decent root system. All these trees are on M111 rootstock.

All my apple trees have defoliated at least once this year, I water them once a week if there is no rain. I grow a few apple trees on a different rootstock (dwarf) in Houston with no problem. I've given these trees a lot of attention, mulching, regular watering, etc. because they are in an open area; no other trees around and are subject to extreme heat and the occasional strong wind. I followed the planting instructions from the Extension web site. The soil where they were planted is sandy for about 1 ft deep with our typical clay under that. The area is high, does not sit in water. I had the soil tested before I planted the trees and the pH was 7.1 (if memory serves me).

I was hoping you could consider this case and let me know what you think the problem is.

Answer: Cotton root rot rarely kills within 12 months--it's usually the 2nd or 3rd yr. Symptoms don't appear to be Cotton Root Rot.

All trees defoliated one or more times in 2004? What was temporally associated with that? Grasshoppers eating leaves? Drought stress? A time of numerous days of heavy rain? The poor growth suggests a site or management problem. The white crystalline material on the specimens near the soil line was unusual. Have you been applying fertilizer frequently? If so, this could be salts accumulating? That seems unlikely in a high rainfall area. Also, there appears to be some type of dark canker-like area in wood at the base of the trunk. This looks like a stress canker, perhaps tissue died in this area at the same time leaves dropped off. Some people apply a white-wash or white latex paint to the trunk to reflect heat in mid-day. The blue-green fungus is probably Trichoderma or Penicillium fungus, which would be secondary invaders of plant tissue killed by something else, during times of high soil moisture. In your case, it looks like stress, then drowning by irrigation when you attempted to revive the trees. Perhaps we should call the local plant police for suspected plant abuse!

One foot of sandy soil over sticky gumbo clay is not ideal for apple. You should probably stick with some ornamental that tolerates your soils. If you insist, you might try again building up a 2 to 3 ft berm 3 to 4 ft. wide at the top using sandy well drained soil amended with organic matter. Mulch the berm, but do not pile mulch up against the trunk. Irrigate often in hot dry weather.

Mark Black, Plant Pathologist