Symptoms and Signs
Symptoms of bleeding canker first appear in early spring, soon after leaf emergence. Young canes exhibit "hooking" at the terminal growing point, leaf wilt, blight, and canker formation. Externally, cane symptoms include dried, shriveled bark. Internally, affected tissue becomes discolored, appearing red-rusty brown. A pruning wound is often associated with the canker. Cankers may occur on canes, cordons, or trunks. Plants are often killed back past the bud union when trunks are attacked. Less severely affected plants generally resume growth in late spring. When regrowth occurs, profuse rusty red exudate (bleeding) occurs from the canker margins, often to the extent that bark tissue is discolored. Suckering is extensive from rootstocks of severely affected plants.
Comments on the Disease
Bleeding canker has been observed in most areas of the state where kiwifruit are grown. Pseudomonas syringae has a wide host range and is believed to overwinter on kiwifruit vines as well as on weeds and grasses in vineyards. Although widespread, this disease is not a major problem in kiwifruit. Young vines that have been weakened by freezing or chilling injury are predisposed to infection.
Control of bleeding canker is currently unresolved, although protecting vines from stresses caused by winter injury should alleviate disease severity. Prune infected vines when symptoms are observed. Make cuts one foot below the leading edge of the canker.