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Saturday, April 24, 2010

Slow budbreak

It has been a long and wet winter here. Bud break is about two weeks behind in general due to the low temperatures and frequent rain. Two weeks ago Clear Lake surpassed the official "full" mark and more cold rain is in the forecast. Another benefit is that the frost season is running out. 
The downside is that much like teenagers, grapevines are at the mercy of their hormones. As soil temperature warms the growth cycle starts to kick in. There is a brief but traumatic point between the time that the buds start to awaken and the fact that they can not produce any nutrients until they are  mature enough to begin photosynthesis. The grapevine is in fact living off stored energy from last year while it is unable to produce any to support its new growth. The vigor off this hormonally controlled cycle is effected by several factors.

Now, look at these two pictures. These are both Barbera. When we prune them, the intention is to leave two fruitful buds per spur (the wood protrusion).  Each bud produces a cane that generally produces two bunches of grapes. This particular clone of Barbera puts out very large bunches, and when estimating the crop load per vine we might remove every fourth bunch to prevent overcropping. So, looking at the pictures, there should only be two buds.So why are there 12 instead? Well, those winter conditions, temperature shifts, the slowness of bud break, the state of the vine when it went to sleep last fall - all of these effect this growth. It may be that the painfully slow budbreak (it took about two weeks to look like this) has forced more latent buds to push in order to produce the photosynthetic capacity necessary for life since the shoots are just not growing yet.

What all these buds mean is a huge amount of hand work removing them all so that only the two originals remain. Remove them too early and the hormones will trigger more growth. Too late and the vine has wasted energy and you end up basically repruning everything with shears. Either way, it pretty much just is what it is. Late bud break can push harvest back a bit, but all the rainfall is encouraging, and everything is looking pretty good!

1 comment:

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