Issue link: http://read.dmtmag.com/i/111102
SOIL REMI COHEN & CELLAR Estimating Your Crop Methods for achieving optimum accuracy rop estimation is not an exact science. After all, it is just an estimate! It is unfeasible to count the number of clusters on every vine in the vineyard, and it is impractical and wasteful to take too many cluster weights. However, by counting and weighing the clusters on a percentage of vines within the vineyard, it is possible to get a reasonably accurate estimate of the number of clusters per vine or block, and their weight. Vineyard yield estimates are critical to achieve the vine balance desired. In order to meet contractual restraints and to reach wine-quality goals, thinning decisions are based on these estimates. Thinning protocols need to be based on the number of clusters per vine and the estimated final cluster weight in the context of the season; vine vigor and degree-day accumulation relative to the calendar date should also impact thinning decisions. It is best to begin estimating crop as early in the season as possible. In addition to being critical for determining thinning protocols, crop estimates can be used to meet grape demand. Wineries may need to supplement grape supply in a lower-yielding vintage, or consider selling additional fruit in a larger vintage. It may also be possible to adjust your barrel order and other supplies such as yeast, nutrients, etc., to meet the anticipated quantity of grapes. DON'T RELY ON BUD DISSECTION Although some viticulturists perform bud dissections in the winter before bud w w w. v w m media.com break, the procedure is laborious. To get the most out of bud dissections, they need to be performed year after year in the same blocks, using the same protocols. Over time, some correlations can be drawn between bud fruitfulness and cluster counts and vineyard yields, but there are many factors that affect ultimate yields throughout the season – including cluster size, and berry set and size – that dissections are not reliable and must be combined with other estimation techniques. The average number and weight of clusters are important factors in determining yields. SHORT COURSE + Crop estimation is not an exact science. However, bud dis+ To estimate yield per acre, multiply section can be useful to the number of producing vines per make pruning decisions; acre, by the average number of clusmore buds can be left in ters per vine, by the average cluster a year where buds show weight. low fertility counts. Addi+ The amount of samples taken should tionally, bud dissection can increase with increasing variability determine if there is a high within a block. incidence of primary bud necrosis, which will impact + The lag phase of berry growth is usuyields the following season, ally the best time to weigh clusters. and is an indication of other + Take cluster weights at harvest and issues such as excessive make a record of the increase in bud shading, irrigation or weight between lag phase and harfertilizer applications. vest each year. More significant data can be collected once shoots have elongated so that clusters are easy to see. Cluster counts can be taken on a percentage of vines throughout each vineyard block. The percentage will vary depending on the size of the block and whether there is a lot of variability within a block. The more variable the block, the more samples need to be collected to get a M a r - A p r 2 0 13 | V I N E YA R D & W I N E RY M A N A G E M E N T 33