Kari Peter, Ph.D of Penn State Fruit Research and Extension Centre, talks about Sudden Apple Decline (SAD) or Rapid Apple Decline, which has devastated orchards in Ontario, New York State, Washington and Pennsylvania.  Apple trees die for many reasons and diseases like fireblight can also spread quite rapidly. But this problem, which is called Sudden Apple Decline (SAD) or Rapid Apple Decline can be identified when the dying apple tree seems to be infected around its graft union. You might see the bark at the graft union peeling off. Then the problem moves up the tree, killing the tree, but the root stock will still be alive and well and unaffected by the disease. The host of The Urban Forestry Radio Show and Podcast is Susan Poizner of the fruit tree care education website www.orchardpeople.com.  Tune into The Urban Forestry Radio Show LIVE by going to RealityRadio101.com on the last Tuesday of every month at 1.00 pm Eastern Time.Learn to grow organic fruit trees successfully. Sign up for OrchardPeople.com's premium online courses at https://learn.orchardpeople.com/.