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Viticulture Association of the Santa Cruz Mountains

  Bloom II

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Vine Talk, May, 2008: 
 

Bloom.

Such a cold spring and yet the grapes press on, stretching out their shoots, greening their abundant buds, enlarging the canopy.  The life goal of the grape is to reproduce, so in spite of all adversity it will sacrifice everything to ripen its seed.  The flesh surrounding is naught but protection in that endeavor and for us indeed the grape plantís trash is our wine treasure.

This cold spring has in many regions wreaked terrible havoc. In Mendocino and Lake Counties there has been tremendous loss of Chardonnay for the year.    Here in Santa Cruz there is spotty reporting of freeze damage.  The bad news is that the black shoots will not spawn fruit for this year or if they do it will be a second crop that may ripen sometime around Christmas.  The good news is that next year in all likelihood the vines will sprout anew and this year will be filed away as an old memory. If you did suffer freeze damage wait and see if any fruit buds survived and take care of what you have. 

If you notice some shoot tips dying off it may not be freeze damage.  You may be seeing botrytis or even evidence of wood borers.  Look at the base of the shoots for small entry holes.   If not, cut the shoot across to see if there is browning in the inner tissue.  This could be a sign of disease damage.

Be vigilant for powdery mildew.  Though temperatures have been cool the over wintering spores have had ample opportunity to awaken and spawn.  Walk your vineyard and look at the underside of the leaves.  Watch for the obvious gray and white powder or telltale pinhole spotting that may appear haloed by yellow and then brown rings. The soft downy fuzz that sometimes covers new tissue is not mildew but can be mistaken for it.

If the canopy is especially dense do not hesitate to get in there and shoot thin like crazy.  Make room for the strong shoots with large buds to mature without encumbrance from their neighbor.  Get rid of the skinny weak shoots that struggle with clusters.  If you want to preserve the shoot position you might save a debilitated shoot but remove the fruit bud.   Give the shoot a chance to put all its energy into reinvigorating the position rather than spend itself coaxing along a cluster that may never properly ripen.

Maintain a consistent spray program and focus on coverage.  Many of you know that I am a devotee of JMS Stylet Oil and if it works for you by all means use it.  If you have another spray program that historically has worked for you, do that.  The point is, get the spray on, get good coverage, and be consistent.  Keep the spores at bay, eradicate them if possible or suppress them if nothing else.  One of these days it will warm up and the spores lying in wait will explode. The challenge of keeping mildew off the vine will then be escalated exponentially.

The time from bloom to set is critical for powdery mildew control.  The vine shoots are rapidly elongating and soft new tissue is formed every day.  This newly formed tissue is especially susceptible to mildew infection.  This is the reason that a consistent early spray program that emphasizes total coverage is essential.  Many of the systemic sprays that are so effective in protecting the canopy after set are less so during this period of rapid growth.  The systemic nature of the chemical spray often cannot keep up with the rapidly expanding vulnerable tissue. 

If you have the spray program well in hand and your canopy is thinned so that you can see around each shoot, good job.  Now take time to look to the vineyard floor and evaluate the weeds.  You donít want anything growing up into the canopy.  This reduces air flow and increases opportunities for disease infection.  Get those weeds down now.  It is too late to spray and under row disking or even hoeing is problematic because of dust or hard soil.  Consider cutting the weeds with a mower or weed whacker.  Many weeds will not come back in the summer heat.  Either way get the weeds out of your canopy.

Test your drip system and make sure the emitters are clean and running efficiently.  Take petiole samples during bloom to identify mineral deficiencies in the vines.

Walk the vineyard, admire its beauty.  Enjoy the beauty of the clover or lupine cover crops if you have them and plan on adding to the biodiversity of your site next year.  Inhale deeply the blooms on the grape clusters.  This is the sweetest fragrance I know, the most exotic of perfumes.  Enjoy this special time and good luck with set.

Buena suerte.

Prudy Foxx, Foxx Viticulture

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