Question
my neighbor has a large cypress tree on the other side of our fence, the tree stump are appearing in our yard and are growing up preety large.  Iam worried the are damaging our house foundation and scared they will start cracking our concrete pool deck.  If I got them removed from a professional tree stump remover co. then dug a 4-5 foot trench along that side of the property and filled it with concrete will that prevent them from growing back on my side of the property?

Answer
These are called cypress knees and are part of the root system. Yes they can damage foundations and patios by pushing up . These can be cut off and a herbicide called Roundup can be painted on the cut surface as soon as they are cut. The root will absorb the Roundup and transport it to the root system killing the roots near by. This will stop the formation of the knees since it kills the roots under them. Depending on how far the knees are from the parent tree it may effect the foliage on that side of the tree since some of the roots will be killed. IF the cutting is done after the tree drops its leaves for the winter the foliage loss will not be a evident as if it turned brown when the rest of the tree is green. You can make the trench which will cut the roots along the line but do not need the concert will. And the trench does not need to be any deeper than 24 inches (the root system is in the first 24 inches of soil). There are root barriers that can be used and these will stop the roots from entering your property. Here is a web link to the root barriers.  http://www.4specs.com/s/32/32-9452.html