Winter injury – Winter injury occurs during harsh winters and/or in the spring when the vine experiences wide temperature fluctuations. Vine or part of bark or vascular bundle may be damaged and then splits when water pressure builds up in the season.

(Photo credit: Mizuho Nita)

Mechanical damage – Trunks may be damaged by mechanical means. Feeding activities by animals and insects, girdling from wires or vegetation, or human activities such as a use of weed eater or improper removal of sucker shoots, can injure the vine.  If the injury damages large part of the vascular tissues, it can result in water stress-type symptoms (short internodes, red and/or yellow discoloration of leaves, etc.).  Moreover, the injured trunk tissues are often subject to be infected by plant pathogens or necrotic microorganisms, such as grapevine crown gall.

(Photo credit: Mark Battany)