Practical Winery
65 Mitchell Blvd, San Rafael, CA 94903
phone: 415-453-9700 ext 102
email: Office@practicalwinery.com
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JULY/AUGUST 2010
SMART VITICULTURE
Round bunches like this are slow ripening, and can be removed during late crop thinning.
Compare the color of leaves in the background with two leaves held in the foreground, indicating nutrient deficiency.
Growing shoot tips in early summer. The position of tendrils near the tip, and the internode length at the tip indicate the vine’s water stress.
Three different clones of grapes were found by close observation in this Tasmanian vineyard, which was thought to be all “Pommard” clone, the middle group of bunches.
Of course, such an impression is transient and not so useful for management. I have been for 30 years a fan of aerial infrared imagery, having first used it to detect phylloxera in the early 1980s in New Zealand. Aerial infrared imagery is now the basic tool for our commercial vineyard grading service. In addition to assessing these images by eye to see patterns, one can also extract pixel data.
Sometimes one’s eyes can also be used to determine differences in soil types within vineyards by their color, but this is not always reliable. Important soil factors of depth and water -holding capacity are not always visible at the surface.
Another good example of the merits of close vineyard observation involves the clonal selection of Pinot Noir in Tasmania, which I have been doing over the last few years. I initially do this at veraison, with a follow-up visit before harvest. Much of our work has been in a vineyard with the “Pommard” clone.
I have found, to my amazement, that what was regarded as a monoclonal vineyard in fact, contains two clones besides Pommard.
One is effectively non-fruiting, and is 10% of the vine population. Another is a large, tight bunch clone which is an obvious mix up with the Pommard clone. Hopefully such a vineyard is not to be found on many properties today, with more strict controls over nursery practice.
At the vine level
In my experience, little can be learned about vines as they pass through bud-break, although one likes to see this happen promptly. Early shoot growth can be the first important indication of vine health, as for example, “spring fever” can indicate deficiency of potassium, and yellow leaf color possible deficiencies of nitrogen and sulfur.
Before shoots have grown to six inches long is a good time to do shoot thinning, a common practice in the U.S., but not inAustralia.My approach is to make a visual assessment of shoot density, to be supported by some rapid vineyard monitoring before a decision to thin or not.
Observation can also detect diseases and pests, though this will not be discussed here, at length. Most vineyard diseases present
clear symptoms, and generally diseases are well-known within a region, so that local knowledge can guide a vigneron as to the diseases to expect. Occasionally, however, new pests and diseases may show up, as was the case with mealybug and European vine moth in California, and the multicolored Asian ladybug in the eastern U.S.
I am not familiar with any disease that will improve wine quality, and some dramatically reduce it. Proper pest and disease management is fundamental to a higher quality vineyard.
Bloom and fruit set
Bloom is an important time in the vineyard. An astute observer will note the duration of bloom and any problems that may affect fruitset, such as the adhesion of caps following rain. My present researchwith PinotNoir in Tasmania is highlighting cluster form and location as they affect the onset and speed of both bloom and veraison, and potential wine quality. Although these ideas are yet to be refined, it seems that the non-classical bunch shapes sometimes evident at bloom may be an undesirable contribution to harvest.
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