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Blackheart results from freeze damage to xylem (vascular) tissue. Tree decline often results if large amounts of tissue are killed. Damage can occur when trees have not hardened off properly in fall and during particularly cold winters. Excessive nitrogen availability late in the growing season and/or a hard early fall freeze before trees develop their hardiness may be factors. Some less hardy varieties and rootstocks are more prone to blackheart.

Blackheart injury to trunk (Strang, UKY)
Blackheart injury to trunk.

(Photo: John Strang, University of Kentucky)

    

Management:

  • Avoid late season nitrogen applications
  • Begin pruning in February after coldest winter temperatures have passed
  • Prune youngest trees in late March as they are more susceptible to winter injury

    

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