With two more days of rain on the way, and another week of unsettled weather in the forecast, we are on our way to catching up with our ‘normal’ rainfall.  The unseasonably warm weather of January and February has now cooled to more normal temperatures, and vines that were starting to push new buds have slowed a bit. As buds start to push, we are now hurrying to finish our final pruning cuts.

Many have asked me why some vineyards are pruned ‘all the way back’ while others are left with long canes.  The answer has to do with several factors; disease control, frost protection and labor utilization.

Disease Control.  There are a number of fungal disease complexes, collectively referred to as ‘Eutypha’, or ‘Esca’.  These fungal spores are released by the presence of free water….rainfall.  Hence, the longer we can delay making the final pruning cuts, the lower the chance of a rainfall induced spore release infecting the vines. The infection site for the vine is at any new, open pruning wound or cut, much as a  cut on one’s finger is a potential site for infection. 

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An unpruned Cabernet vine with all of last year's growth dormant for the Winter season.

Disease symptoms progress slowly from the point of infection toward the center of the vine.  A dead or dying section of wood within the vine, known as a canker, develops, affecting the productivity of that section of the vine, and in advanced stages, over several years, will kill the entire vine.  By doing a ‘partial’ pruning of the vine during the major rain producing months we expose an open wound to infection, but then prune off that infection site with the final cuts done as late in the Spring as possible.  This is why you see many vineyards with 12 – 14 inch cane wood left until just prior to bud break.  When the canes are cut back to the first two buds, the potentially infected original cut is removed.

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'Pre-pruned' vine with most of last years growth already removed from the trellis wires. This vine awaits final pruning cuts just prior to bud break.

Frost Control.  As Springtime temperatures start to warm and sap starts to flow in the vine, the first buds to push will normally be at the terminal ‘end’ of the cane.  The emergence of new growth can be delayed a few days by allowing the terminal buds to push, and then pruning back to the two base buds.  What makes this problematic is there is a high risk of breaking off new buds when removing the brush from the trellis system.  If, however, the canes are ‘pre-pruned’ to 12-14 inches and the brush removed during winter dormancy, the final cuts can be made just as the end buds are starting to push.  With the majority of the brush already removed, there is little danger breaking off base buds that might have already pushed.  A few days of free frost protection can be achieved this way if the operations are timed properly.  Some years, a few days can make the difference between frost damage, or healthy, fruitful shoots for the new year.

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Fully pruned spur with buds starting to push. You can see how easy it would be to break off these tender, new shoots if you were pulling brush when they are at this stage.

Labor Utilization.  By delaying the final pruning cuts until bud break, we can keep our field workers in the vineyard during a time when there is normally a slack period, waiting until the shoots start to grow and we need to make our first suckering pass.  

As 2012 begins to unfold, we are still waiting for buds to push in most vineyards.  Rain the next two days will keep minimum temperatures above freezing, but unsettled weather in the coming week will likely present some near freezing temperatures, and frost conditions when the skies clear.

 

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With the tease of Spring for a couple weeks in early February, it’s not difficult to think Winter is over and done.  But God has a way of letting us know he is still in charge.

April 1, 2010. Snow Cap on Mt. St. Helena.

Snow in San Francisco!! Perhaps on Friday or Saturday that could happen.  I am expecting to see snow ringing the Napa Valley by the weekend, but that is still only the end of February.  In 2010 we had a snow cap on Mt.  St. Helena on April 1st, and it wasn’t an April Fools joke.

The good news for now, is that the vines are still dormant, although it won’t take more than a couple of days at 75 degrees to see buds start to pop into this years new growth.

You may have seen a lot of  vines in the Valley this year with “long haircuts”.  Our Cabernet was “long” pruned a month ago, leaving canes 12 to 14 inches long.  Just as we see signs of bud swell this spring, we will go back into the vineyard and “finish” prune the vines, selecting the spurs to remain for this year’s crop.

Wicker Vineyards Cabernet Vines Waiting For Final Pruning Cuts

This buys us a couple of benefits.

First, it allows us to make the finish cuts just as the shoots start to grow.  Without all the long brush to pull from the canopy, there is no danger of breaking off the tender new buds.  This gains us as much as a week or ten days of frost protection by delaying the bud break.

Secondly, this practice helps us control Eutypa fungus infections.  The free fungus spores are released by rainfall, and infect the vine through the fresh pruning cuts.  When we make the final cuts, any early, wet season infection by Eutypa spores is trimmed off before it has a chance to work its way into the main structure of the vine.  This is a great example sustainable practice farming, preserving vine health without the use of chemicals.

First Signs of Spring

Spring is just around the corner.

The daffys always give us a look at some of the first spring color.  Next weekend we will “spring” ahead as we enter daylight savings time so that we can start waking up in the dark again!

We have held off pruning our Cabernet until the last minute, but finished it this weekend.  Many of you have seen the process, but for those who haven’t, here is a short video clip of one vine being prepped for the season.  This is one of the most important steps in each growing season, as it not only sets the potential for the crop level, but determines the shape of the vine for years to come.  Notice the skillful thought and care that goes into each cut.  There is something therapeutic about the “clip, clip, clip” of the pruning pace.   It kind of puts us  “at one with the vine”.

You will notice that the canes being removed are being piled in the row behind the pruner. When we are finished, we will pick up all the small brush piles, carry them out of the vineyard, and mulch them for compost.  Two years from now, this compost will be returned to the vineyard rows to help with moisture retention and weed suppression.