Your Guide to Easy Fruit Tree Care

Episode 44: Dying Apple Trees and Sudden Apple Decline (SAD)

If you think losing one home-grown apple tree to disease is disappointing, imaging having your healthy young orchard turn into a mess of dying apple trees. This is happening to orchards across North America and researchers can't figure out why. So far, the phenomenon called Sudden Apple Decline (SAD) or Rapid Apple Decline, has devastated orchards in Ontario, New York State, Washington and Pennsylvania. 

In this episode of The Urban Forestry Radio Show, Kari Peter, Ph.D of Penn State Fruit Research and Extension Centre, explains how she has witnessed this problem first hand. One day the trees in her research orchard looked perfectly healthy. A few days later their leaves went yellow. Then, within two weeks, entire blocks of her test orchards were filled with dying apple trees. The trees were dead within a matter of weeks - many of them had a sad-looking harvest dangling off their lifeless branches.

Dying apple trees in a an orchard. This is seen frequently with Sudden Apple Decline. Photo credit: Kari Peter, Ph.D.

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.

Most of the dying apple trees are younger trees between 2 and 8 years old. It seems bigger, older apple trees are more resilient. They can survive the problem. Or maybe they don’t get infected at all.

Trunk of tree killed by Sudden Apple Decline (SAD)
Sudden Apple Decline begins in the graft union, and then it moves up into the tree. As you can see in this image the apple tree will die but the root stock survives (see the green leafy suckers coming from the base of the tree). So if see apple trees dying while their root stocks survive, it could well be Sudden Apple Decline. Photo Credit (Kari Peter)
Kari A. Peter, Ph.D is one of a team of researchers from across North America who are collaborating to find out the cause of Sudden Apple Decline.

Researchers are now scrambling to discover why Sudden Apple Decline is spreading. Is it a virus? Is it the result of herbicide damage? Is there a fungal element? What role does stress or winter damage play? Why is it that most of the dying apple trees are grafted onto M9 dwarfing root stock?

Researchers also don’t know if it’s only affecting tightly-planted high density orchards. Or are young apple trees dying in the urban setting as well?

Experts including Kari Peter, Ph.D. are now collaborating to get to the bottom of the problem to prevent more tree casualties and the devastating financial losses that growers are experiencing as a result. Many of these research teams have applied for grants and are waiting for funding so that they can dig deeper, identify the problem and find the solution.

Why are young apple trees dying across North America? Here is what you will learn in this episode:

  • 4:00 How did Dr Peter first discover Sudden Apple Decline?
  • 7:00 What is the difference between Root Stock and Scion Wood and why is that important to know when apple trees are dying and you want to know if it is as a result of Sudden Apple Decline?
  • 9:25 Is there a cure for Sudden Apple Decline?
  • 10:30 How did Dr. Peter realize the problem was bigger than just her orchard?
  • 13:40 Will this disease wipe out an entire orchard?
  • 15:30 What age of tree is mostly impacted by Sudden Apple Decline?
  • 16:25 What stressors are affecting trees?
  • 18:40 Is there any known prevention for this disease?
  • 20:00 Could sealing over the graft union prevent Sudden Apple Decline?
  • 23:50 Is Sudden Apple Decline affecting a wide variety of apple cultivars?
  • 30:30 Where could apple growers go to report disease on their trees?
  • 33:00 Does the temperature of the climate affect the prevalence of Sudden Apple Decline?
  • 36:00 What role are herbicides playing in tree stress?
  • 37:30 Where could more information from Dr. Peter be found?
  • 40:30 What do dying apple trees that are suffering from Sudden Apple Decline look like?
  • 41:10 Are there nutrients that could help trees fight off Sudden Apple Decline?
  • 43:10 Are high-density orchards good for trees?
  • 50:00 What kind of damage does Sudden Apple Decline cause?
  • 54:00 How can growers protect their trees from this disease?

The host of the Urban Forestry Radio Show and Podcast is Susan Poizner of the fruit tree care education website and the author of the award-winning fruit tree care book Growing Urban Orchards. You can listen to previous episodes of The Urban Forestry Radio Show and Podcast at and you can subscribe to the iTunes podcast.

Tune into The Urban Forestry Radio Show LIVE by going to on the last Tuesday of every month at 1.00 pm Eastern Time and email your questions in during the show to [email protected] This show covers fruit trees, food forests, permaculture and arboriculture. After the live broadcast, archived podcasts are available at 

The Urban Forestry Radio Show and Podcast is brought to you by our Gold Sponsor, Stark Bro's Nurseries and Orchards . Our bronze sponsors include Whiffletree Nursery, Earth Alive, Acti-Sol and Mark's Choice.  

Click below to listen to the show podcast now. 

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Susan Poizner of Orchard People

Speaks at conferences and symposiums across North America about fruit tree care, urban orchard design, fruit tree cultivars and more.
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Earth Alive
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