Question
Our neighbor has three massive river birch trees just on his side of the property line, but because the sun come round our way they are all overhanging our garden by about 30ft. The trees are stunting the growth of our plants and the roots are beginning to tear up our drive, they are a terrible nuisance. However one of them has developed a large black wet looking area on the trunk and the upper branches are dying. Can we hope that he may have to take this tree down?? But our main concern, is whatever is wrong with the tree going to affect our trees? We have a very valuable rare Japanese Maple in close proximity is this in danger? Thank you for any information you can give.
Answer
Sounds like the tree has been attacked by an insect called a borer. They will bore into the bark and trunk causing the tree to bleed. These wounds and others can cause a decay fungus to enter causing also bleeding and over time the tree will be come hollow. The borers could kill the tree if the tree is under stress. But insects are specific to different species of trees so a borer that infests a birch tree would not infect a different species of trees say the maples. If the larger limbs in the crown of the tree are dying it sounds like the tree may not make it. And if the larger limbs are dead the tree maybe classified as a hazard tree and should be removed. Hazard trees are usually those that if the tree is dead or large limbs are dying and there is a structure that would be damaged if limbs or tree fell the tree is a hazard and should be treated. Here is a web link to information on hazard trees. The shade from the over hanging limbs would cause the garden problems and since they are on your side of the fence they can be pruned back to the land line. Also the roots on your side can be pruned along the drive to stop them from growing under the drive.
http://www.na.fs.fed.us/spfo/pubs/howtos/ht_haz/ht_haz.htm
