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La Crescent Harvest at Coyote Moon

(reprinted from Veraison to Harvest issue #3, September 13, 2013)

This past Tuesday, we harvested a small trial of La Crescent grapes at Coyote Moon vineyards near Clayton NY. We are calling it the ‘crop load’ study, although it might more properly be called the ‘cluster thinning’ trial. Cluster thinning is used by growers to adjust for overcropping, the idea being that with less fruit on the vine, the remaining grapes will ripen more evenly –and fruit chemistry will be improved at harvest time. In particular, with the Northern Grapes cultivars, the hope is that managing the cropping level might provide growers with a means to reduce the high acids that are characteristic of these cultivars.

The study:

We did three treatments. 1) Control (nothing), and two cluster thinning treatments, where we removed all but the basal cluster (1 cluster per shoot) at either 2) before bloom (flower thinning) or 3) at fruit set. Here’s how the yield components looked. Unthinned vines had 86 clusters per vine, and the thinned treatments had 38 (fruit set) or 47 clusters. Yield was cut in half from 10 lb/vine to 5 lb/vine. The result? The unthinned grapes had slightly lower brix (22 vs 23 in prebloom thinned), slightly lower berry weight, but no difference in Titratable Acidity or pH.

Conclusions from this year:

In these vines, this year, removing half the clusters and cutting the yield in half did not change the fruit chemistry as one would hope. There could be several reasons for this: 1) These are young vines, and not up to their full cropping potential yet. 2) Even the high crop load did not challenge the vines. 10 lb/vine at 7×9 ft spacing is about 3.5 tons per acre. 3) clusters were poorly filled, in many cases, which could be a carryover effect of nutrient deficiencies (since corrected) in 2012. 4) Ample moisture and vine growth produced a bigger canopy (and higher vine capacity) than would be the case in drier years.










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