Cause Fusarium lateritium, a fungus. Frequently forms on twigs or branches damaged by freezing.
Symptoms Tan cankers with a purple border where tissue should be green. Peach-color elliptical fruiting bodies (sporodochia) develop within the cankered area where the lenticels are located.
Cultural control
- Prune off cankers well below the discolored area.
- Plant trees in sheltered areas, which are less likely to be affected by winter injury.
Reference Proffer, T.J. 1996. First report of Diplodia mutila on golden-chain tree (Laburnum x watereri). Plant Disease 80:1303.