Question
I am trying to determine if our tulip tree is diseased and should be cut down. It was on the property and quite huge when we bought this house over 45 years ago. I would say that it is at least 70 feet high.In the past 6 years it has dropped two large lower limbs; the latest being this week after much rain. The core of the limb where it attaches to the main trunk is darker than the rest of the limb for about 2 feet from the attachment point. Does this indicate disease? Is this normal for a healthy tulip tree? I did not see evidence of insects having eaten away at it nor is the wood excessively mushy although it is softer than some woods. The tree is situated behind and about 20 feet away from our house; at one time there was a septic tank about 15 feet away from it but it is no longer in use. The tree however is located 10 feet from a trout feeding stream and I believe has access to an ample water supply. I hate to have this tree removed not just because of the expense but because of its longevity. I always believed that trees were program to live forever but does the tulip tree have a set lifespan?

I would appreciate any insight you can give and thank you ahead of time.

Answer
Yellow poplar has a long life span 150+ years. It sounds like a decay fungi that has entered the trunk and grown into the lower limbs. Yellow popular is fairly resistant to these decay fungi but can get them. IF the upper foliage is healthy looking the tree is ok. What happens is the decay fungi enters a wound in the trunk and decays the woody part of the tree. It does not cause any problems to the live cells but only attacks the dead wood in the center of the tree. As it grows up the trunk it can get into the lower limbs and when they break the wood in the center of the limb should be softer than the out wood. I would 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 water in good--fertilize just before a rain storm and you will not have to water.  This will increase the overall health of the tree. There is no way to treat the decay fungi in the tree but keep the tree healthily growing. As long as the foliage is full and green it should live many more years. IF more of the lower limbs break you can prune the lower limbs off and this will stop the breakage and falling. Without looking at the tree and boring into the trunk this is about all I can tell from your description. You might try calling the State Forestry agency in your state and ask one of their Foresters to come take a look. Their number should be in your local phone book.