Question
Is tree fungus deadly?
I am in Houston Tx, land of drought and humidity. I have a very old pear tree planted over 55 years ago that is approximately 30 feet tall. The top is green but the trunk is hollow and discolored. The tree is in a well drained area, protected location surrounded on the south and west sides by a building about the 5 feet away. We have trimmed, nurtured, fed and watered it through the terrible Houston heat and drought this year. It has developed a large fungal growth on the bark, about 3/4 inch thick that appears as a uniformly white spongy material. The growth is somewhat in the shape of a pyramid growing from the ground (10 inches wide and covering 1/3 of the tree's diameter)to approximately 2 feet up the trunk. The same fungal growth appeared on a nearby Hackberry tree, over 45 feet tall, that died early in the drought this year(now removed) and on another stump of a hackberry tree we removed several years ago.

I would appreciate any information concerning this fungus and the prospects for this ancient tree. Is the fungus a consequence of the tree's imminent death or is it a cause?

Should the fungal growth be removed and treated with medication?
Is there anything that can be done to save the tree?

Answer
It is one of the decay fungi--the growth is the fruiting body much like a flower. These are the fruiting bodies of fungi.  If they are connected to the trunk or roots then this a decay fungi. If they are not connected then these are just mushrooms growing in the duff of the soil. Many wood rot fungi can be identified by the distinctive shape, color, and texture of the fruiting bodies that form on trees. These structures, called conks or brackets, often are located around wounds in bark, at branch scars, or around the root crown. But with out a picture I would only be guessing which decay fungi this is.

Decay fungi enter the tree trunk through wounds and will over time eat away at the woody center part of the tree. They do not infect living cells so they are not really a health problem with the tree.
There is not really anything that can be done about the fungi growing in the trunk. It is not a problem unless you start to have the large limbs break and these are hollow. This would mean the decay has grown up into the trunk and maybe come a problem of breakage of large limbs and the trunk.  This will not be a real problem for many many years.

I would recommend that you fertilize the tree with 10-10-10 fertilizer at the rate of 1 lb of fertilizer per inch of trunk diameter scattered around the tree and watered in good. Apply just before a rain storm and you will not have to water.

There is not a fungicide that can be used on these since they are living in the wood on the inside of the tree trunk. The tree will not die from these decay fungi but could be subject to wind breakage. Fertilizing will increase the overall health and allow thew tree to survive many more years.