Tree branch with fire blight

Photo: William Jacobi, Colorado State University,

Updated: February 28, 2023

Fight fire blight by leaving an “ugly stub”

The fire blight bacterium is a systemic pathogen that can move rapidly into healthy tree tissue. Backyard orchardists are often unaware that pruning out infected shoots and limbs during the growing season can further spread the disease.

Follow these pruning guidelines to improve fireblight control 

  • Use very sharp pruning tools to remove infected limbs 8-12 inches below visible symptoms.
  • Do not make the cut all the way back to another healthy limb or spur. Instead, leave a 4 inch long naked (“ugly”) stub. (The bacterium colonizes the ends of pruning cuts and produces cankers which serve as a source of inoculum for continued infection).
  • Mark the stubs to make them easy to locate. (Spray paint in a bright color works well.)
  • Remove and dispose of the infection-carrying “ugly stubs” during dormant pruning (November-January).
Ugly stub pruning diagram