01-Jun-09 09:19 | Eric Stafne

Cold damage does not always show up right away.  Sometimes vines can appear health when they are pruned, but never break bud.  Sometimes they can break bud and grow normally until hot, dry weather comes.  The stress of these conditions will cause the vine to start shutting down its new growth.  It can no longer support it.  The conducting tissues have been injured — not enough to be a problem early in the season — but the effects come on later.  This situation is not at all unusual.  I was just down in Ardmore at the Noble Foundation and looked at some of their grape vines.  One ‘Cabernet Sauvignon’ vine was completely dead, but had looked fine at pruning time.  It did have obvious freeze damage — cracking on the vine.  Why did it die whereas others did not?  Sometimes there is no answer; at least no obvious one.  Some of the other vines appeared to be struggling and others looked great.  What I suspect happened was that the Cab vine never gained full dormancy and perhaps was growing too late into the fall when it should have been hardened off.  Looking at the weather data, nothing really jumps out at me.  There was a 12 degree F event in January that may have had an effect, but difficult to say.  At any rate, don’t always assume that poor growth, dying growth, and crinkling leaves are caused by spray drift.  It may be that the vine is showing symptoms of winter cold damage.