Cause Apple dead spur is caused by a graft-transmissible agent that apparently originated in the Western United States. The pathogen has not been identified, although Apple stem pitting virus, Apple stem grooving virus, and Apple chlorotic leaf spot virus have been detected in diseased material. The only known means of disease spread is through the use of infected propagation material.
Symptom Trees develop long segments of blind wood that produce no fruit. The death of fruiting spurs is most common in the interior of the tree resulting in sparse canopy and fruit bearing spurs at the shoot tips.
Cultural control Use only virus-tested (and found to be free of all known viruses) planting stock.
Reference Hadidi, A., Barba, M., Candresse, T., and Jelkmann, W. 2011. Virus and Virus-like Diseases of Pome and Stone Fruits. St. Paul, MN: APS Press.