Question
I have  4 aspen trees in one area of my yard.   Is there any way to kill new shoots?  Also, the roots are coming up in lawn area, is there anyway to prevent this?

Answer
It is really difficult to control aspen shoots that develop on aspen roots.  When they're little you can keep them mowed off in the lawn.  In beds you can try to pull them or snip them off when they're little.  Herbicides should not be used because they can travel through the roots and harm the parent tree.  There is a product called Sucker Stopper that may help. This is made from the plant growth regulator napthaleneacetate (NAA). And is used to stop the plant from putting out suckers of new growth. Here is additional information on this product --check with your local nursery type store. http://www.montereylawngarden.com/faqs/suckerstopper/