Apricot Tree Die Back

Question:

 I'm concerned about my fifteen-year-old Apricot tree. The growth was lush and vigorous in the spring, but now one section of the canopy is dead. It happen quickly, starting in early June.  What’s going on, and what must I do to prevent it?

Answer:

  • Phytophthora Root Rot and Euypta Die Back are the two primary causes for sections of the canopy in Apricot trees to die. They affect major and minor branches/limbs.
  • Phytophthora Root Rot is a soil-borne fungus that attacks the roots of Apricots, along with Cherry, Peach, Nectarine, and Plum trees.
  • Root rot is the primary suspect when a limb or section of a tree fails to break dormancy and leaves out in the spring.
    • It's also the reason when for no apparent reason, the foliage on a branch collapses/wilts and turns brown shortly after the rainy season concludes. You would expect this problem in clay soils that drain poorly and receive excessive summer irrigation. A good soaking with a large watering basin once every three weeks is sufficient for mature Apricot, Cherry, Peach, Nectarine, and Plum trees.
    • Phytophthora Root Rot is a slow-developing disease. You'll find more information at http://www.ipm.ucdavis.edu/PMG/r5100611.html.
  • That being said, I don't think this is your problem. Instead, Euytpa Die Back would be my educated guess. Euytpa Die Back is only a problem with Apricot trees and grapes. It's an airborne fungus that enters the tree through the pruning wounds. When it’s damp and wet after pruning. You need a week or so of dry weather so the pruning wounds callus over. Euypta Die Back was not an issue in 2022 because of the dry conditions. The affected branches or limbs collapse around Memorial Day or early summer for no apparent reason. You correct this by changing the time of the year you prune. It's now recommended to prune Apricots from August through early November. Although the foliage hasn't turned yellow and dropped, they're in the early stages of dormancy as the year's growing and fruiting cycle is finished. The biggest drawback of fall pruning is the leaves as they obscure the branching. So it’s a little more difficult on which branches need removing.  You'll find more information at   http://www.ipm.ucdavis.edu/PMG/r5100911.html.  

Note: When fruit trees are under stress from Phytophthora Root Rot and or Euypta Die Back, borers can attack and be a secondary problem. It's not uncommon for globs of amber-colored sap to be on the limbs and branches. It's very possible for an Apricot to be suffering from both problems concurrently. The ideal prevention is to keep the tree healthy by not over-watering during the summer months and avoiding planting under the canopy. Watering once every three weeks is sufficient. Each tree should have a watering basin around them that is six to eight inches high and extends from the trunk to a foot beyond the drip line. This basin is filled multiple times when you water.