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GRAPE GRO WING Alasco_Nov04 10/1/04 11:44 AM Page 1 ALASCO Rubber & Plastics ...for 20+ years the innovative leader in solid & fermentation barrel closures! DALCO DUALL • fermentation bung • solid bung • easy to use • easy to clean CARBOY DUALL • fits over outer neck • fits carboys & beer kegs SOLID BUNGS • custom colors • with or without grip • a size for every barrel ElectroSteam_June08 4/8/08 2:40 PM Page 1 full line of winery equipment • bottling line parts • tank gaskets & seals • custom molded parts • 805/543-3008 phone • 650/595-4100 phone • 805/543-5349 fax • www.alasco.com • email@alasco.com Vines per acre X You may have fabulous-looking potential clusters, but if bad pollination weather occurs as the crop develops, you don't have good advanced information. On the other hand, if you can tell that there are not as many cluster primordia in the buds, and that what is there is small, you may be able to tell that a short crop is likely to happen. Since this technique is expensive, not many growers or wineries depend on it for crop forecasting. More accurate techniques rely on actually measuring the yield potential by sampling and weighing clusters in the vineyard. The basic formula for yield of tons per acre is: Average number of clusters per vine X in pounds Average cluster weight ÷ 2,000 = Predicted yield in tons per acre Sampling procedure usually calls for using at least 10 vines in the block that are marked and used from year to year so that you can also go back and check fruit:shoot weights to see how effectively you are balancing your vines. (All indications are that fruit:shoot ratios somewhere between 4:1 and 8:1 produce good quality fruit depending on variety, target price point for the wine, climate and location.) For this to work well, you have to have a fairly uniform block and choose very representative vines. If your vineyard is quite variable, you might have pretty poor results. This technique is quite accurate when used just prior to harvest. Davison_Dir06.qxt 10/28/05 2:25 PM Page 1 If you want to know sooner than that, you can plug in average cluster weight values instead of actual weights if you have tracked the performance of the vineyard over the years. The only draw- back is that seasons tend to be quite variable based on how grape cluster development and pollination fare, so it is still an estimate with potentially considerable variability. There is also the "lag phase" method of estimating yields, but clusters are sampled and weighed earlier in the season. Grapes grow through three phases during growth and ripening. In the first phase, berries grow rapidly as cells divide and increase in number. This phase lasts about two to three weeks. In the second phase, berries grow slowly, and sugar accumulation begins. Acid content is at its highest. Fruit begins to lose chlorophyll. Phase two lasts about two to four weeks. During phase three, the fruit begins to soften (verai- son) and gain color, resuming rapid growth. Sugars accumulate and acidity drops. This phase often continues for five to eight weeks. With the "lag phase" estimation technique, clusters are weighed Davison Winery Supplies 1819 NE Baker St., McMinnville, Or 503-472-1711 The Northwest's Most Complete Winemaking Supply! For the professional or the beginner, we have it all. www.dwinesupplies.com 54 Wines & Vines JUne 2012 about mid-way through the ripening process. This is often around 50-60 days after flowering (when at least 75% of the florets in the cluster have shed the little caps known as "calyptra"), depending on variety and location. It is about the same time that the seeds are starting to harden and cannot be easily cut with a sharp tool. Final crop weight is estimated at somewhere around 1.7-2.0 times the average weight of clusters at this point. Many growers and winer- ies use the fairly simple technique to estimate the crop for the year. This may help to determine whether the crop should be thinned, since veraison is considered the best time to adjust crop load. For red wine varieties, color thinning is a good way to do it; the green- est fruit is dropped until a reasonable fruit load is determined. A wild card in all of this is late-season heat, which can cause dehy- dration and loss of cluster weight. Some varieties are very prone to this problem, especially Chardonnay and Pinot Noir in cool climates. Late- season losses of 35% due to dehydration are quite possible and have occurred in recent memory. Likewise, increasing "hang time" can cause considerable loss of yield if fruit is kept on the vines for too long. (Continued on page 56.) Plus Contact Us!