Fluctuating spring temperatures can result in plants looking normal until temperatures rise in late spring. New growth and fruiting clusters suddenly collapse and die. More typically, though, with winter injury, die back occurs to a certain point on the cane, with growth below the die back looking normal. In rare cases, boron deficiency causes die back of canes without wilting or cankers present. A leaf analysis can verify this diagnosis.
Cankers also cause such symptoms, and are sometimes confused with winter injury.
In many cases, winter injured wood is susceptible to canker infection. This fungus tends to infect the lower portion of canes. On young canes, the lesions look like a bull's eye. In older canes, the interior wood is brown. This fungus tends to infect canes through winter-injured wood, usually the tips of canes.