Crop estimation is essential for multiple reasons, including ensuring that your expected yield is not greater than desired or that your vines can handle and properly ripen it. It also helps you understand if your current crop can fully and evenly ripen and allows the winery to prepare tank space and equipment. In this blog, we delve into the proper phenological stages or timing for crop estimation.
1. Just After Fruit Set
The earliest time most growers will attempt to do a crop estimation is just after fruit set. The purpose for estimating at this stage is to determine if the predicted crop level is too high so thinning can be done to ensure the expected yield target is not exceeded and clusters ripen evenly. An additional purpose for estimating at this stage is to provide your buyer / winery with a projected estimate.
If thinning is needed, target shorter shoots with less leaf area to ripen crop and areas of high cluster density (clusters tangled or in shaded internal canopy layers).
Note: Early thinning may hasten the ripening of the remaining crop and increase the berry size.
2. Near Lag Phase (Pea Size Berries)
Near lag phase when the cells in your berries stop dividing is the next time growers may choose to estimate their crop. Just like fruit set estimating, the purpose for estimating at this stage is to determine if the predicted crop level is too high so thinning can be done to ensure the expected yield target is not exceeded and clusters ripen evenly and to provide your buyer with a projected estimate for the season.
If thinning is needed at this phase, growers should again target shorter shoots with less leaf area to ripen crop as well as areas of high cluster density (clusters tangled or in shaded internal canopy layers).
Note: Thinning at this phase may increase crop uniformity, and it is debatable whether it can hasten ripening. Less berry size compensation is expected.
3. 80-90% Veraison
At this phase, clusters are approximately 80-90% of their final weight, so this is the time to get the most accurate estimate and confirm with your buyer that your estimated yield is still on target.
Thinning at this phase can improve harvest uniformity and wine quality by removing:
- Green or severely delayed clusters
- Clusters on damaged shoots
- Diseased clusters (more than 20% disease severity)
4. At Harvest
Crop estimation at harvest is critical for obtaining your average cluster weight to use for your seasonal historical data, so that your future yield estimation will be more and more accurate.
For this estimation, you must harvest 2-3 vines per variety and count the number of clusters per vine. Weigh the whole bin with the clusters from those vines and then divide the total weight by the number of clusters to get your average cluster weight.
To learn more about crop estimation and the use of innovative technologies like proximal sensing for estimation, check out vineyardundergroundpodcast.com/vu022.