Viticulture Association of the Santa Cruz Mountains
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Bloom! It’s hard to believe that we are already into the middle of
May. The late winter rains over-stayed their welcome and allowed Spring to sneak
in barely noticed. Nevertheless we are looking at that time of year when the
need for powdery mildew control is absolutely essential.
If you can get through bloom and fruit set with-out mildew your summer
will be far more enjoyable. Remember
that powdery mildew is not always obvious in the early stages. By the time you
see the powder your vineyard has already built up quite a population and
eradication efforts are required. The rains this year have made the spray program quite
challenging. It is my opinion that the standard suppressant program of Thiolux
or other sulfur programs might provide limited protection because they just keep
getting washed off. Eradicant products like JMS Stylet Oil or Armicarb or
Kaligreen (doesn’t last as long on the foliage) are very effective tools
against mildew in a year like this. They wash off too, but at least they kill
off the spore populations before they go. That way there are fewer spores to be
distributed by the rain. As always, thorough coverage is essential. These
products are not systemic and are only effective on foliage they come in contact
with. Be sure to include a botrytis control spray in your program
during bloom and at set. Serenade
is an organic product available for this purpose. Elevate and Vanguard are among
the alternatives. In addition to sprays it is very beneficial to focus on
improving the canopy microclimate. Shoot thinning is an essential practice this year in most
vineyards. If your vineyard tends
to have extra vigor, late season shoot thinning will not only open up the canopy
but reduce vigor as well. Make sure that your canopy allows plenty of light and
air to surround the developing flower clusters. This allows them to dry out from
the rains, reduces humidity within the canopy, and allows spray penetration and
good coverage. Sprays are far less effective if you don’t achieve good
coverage. On another note, Juan Hidalgo from the Santa Cruz County Ag.
Commissioner’s Office passed out mealy bug traps at the last meeting.
Hopefully everyone has deployed those traps in their vineyard. If you have,
please remember to bring the trap to the next meeting. We will gather them up
and turn them in for examination. New traps will be available at the same time. Turn in the trap even if you don’t see
anything in it – it will still help the Ag Department track the spread of the
bug, or lack of it. Let’s keep up with this program and keep Santa Cruz free
from this pest. There are a number of control programs available if you do have
mealy bugs, so get informed and take action before they corrupt your fruit. This is the perfect year to consider a no till policy in your
vineyard. With all the rain it may be wise to simply keep the ground cover
tightly mowed and avoid tilling or discing. Tearing up the soil not only
disrupts microbial life in the soil, it also makes it harder to drive the rows,
it compacts the soil, it wicks up even more moisture from deeper in the soil
profile, and it creates a dustbowl in late summer. Focus on weed control under
the vines and keep the aisles closely mowed to discourage mites and other pests.
Newly planted vineyards may require a different approach. Remember to take petiole samples at full bloom. Doing so will
tell you the nutritional status of the vines in real time and is an excellent
aid making decisions about nutrient supplements at fruit set and later. Despite the rain, I hope that everyone is enjoying a
bountiful spring. It is the best wildflower year in ages. Make a point of taking
in all the beauty that each season brings. It is such a gift to be here. Happy Spring. Prudy Foxx (Vine Talk column, May 2005) |
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