Practical Winery
65 Mitchell Blvd, San Rafael, CA 94903
phone: 415-453-9700 ext 102
email: Office@practicalwinery.com
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Spring 2011
GRAPEGROWING
Figure 1. The 4-inch hedge retained as a result of mechanical dormant box-pruning applied with Oxbo 24-inch Sprawl Pruner heads (Model 63700), mounted to an Oxbo1210 single-row, tractor-mounted tool carrier in the Syrah vineyard.
Two dormant pruning treatments:
  • Hand spur-pruning of vines to retain 24 buds per vine on 12 spurs (3.5 buds per foot).
  • Mechanical box-pruning to retain a 4-inch hedge of canes with a density of 15 spurs per foot of vine-row (approximately 2.5 to 3 buds per foot) using the implement in Figure 1.
Three shoot density treatments:
When inflorescence was fully developed, three shoot density treatments were applied using the implement in Figure 2.
  • 7 count shoots per foot of vine-row (low shoot density).
  • 10 count shoots per foot of vinerow (medium shoot density).
  • 15 count shoots per foot of vinerow (high shoot density).
Two leaf removal treatments:
  • No leaf removal (control).
  • Leaf removal in the fruit zone on the east side of the canopy.
Leaves were removed with the implement (See photos on first page) in an 18-inch zone at 20 days after bloom.
The effects of these mechanical canopy management treatments on shoot density, canopy microclimate, fruit set, cluster architecture, yield, and fruit composition were evaluated. Not all data collected in the trial is presented here, but this report highlights the most important results.
2010 results
Effect of mechanical canopy management on shoot density In the pruning treatments of Syrah vines, the number of count shoots, noncount shoots, and total shoots per foot retained was not affected by pruning method.
However, for Pinot Grigio vines, the numbers of shoots was significantly higher in the mechanicallypruned treatment.
The shoot-thinning implement was used as needed to apply mechanical shoot-density treatments. In the Syrah vineyard, the density of count shoots, non-count shoots, and total number of shoots per foot of vine-row was influenced by shoot-thinning treatments. Shoot-thinning in the low and medium density treatments reduced the total number of shoots per foot of vine-row by about 30% when compared to high density treatment.
In Pinot Grigio, pruning and shootthinning treatments interacted to affect the count, non-count, and total shoots per foot of vine-row. Generally, mechanically box-pruned
Pinot Grigio that was not shoot-thinned had the most count, non-count, and total shoots per foot of vine-row. Conversely, spur-pruned Pinot Grigio that was shoot-thinned to low density had the least count, non-count, and total shoots per foot of vine-row.
Effect of mechanical canopy management on canopy microclimate The canopy microclimate was affected by some mechanical canopy management treatments. Leaf removal as a standalone treatment had significant effects on percent photosynthetic photon flux density (PPFD) transmittance, number of leaf layers, and percent canopy gaps in both Syrah and Pinot Grigio.
In Syrah, pruning and shoot-density treatments when applied as standalone methods did not affect canopy microclimate. However, when pruning, shoot-density treatment, and leaf removal are combined, the beneficial effects of integrating these three methods are evident in reduction of leaf
layer numbers for Syrah. In Pinot Grigio, the integration of mechanical box-pruning and shoot-density treatment improved the PPFD transmittance. This also translated to more canopy gaps for mechanical box-pruning and low or medium shoot density in the Pinot Grigio canopies.
Effect of mechanical canopy management on fruit set The pruning method, shoot density, and leaf removal treatments did not affect the number of berries per cluster or berry weight at set in Syrah. Leaf removal was the only treatment that increased the number of berries set per cluster in the Syrah. A combination of medium shoot density and leaf removal improved berry set in Pinot Grigio.
Effect of canopy management on cluster architecture Syrah cluster architecture at veraison was mostly affected by dormant pruning method and shoot density. The number of berries per length of rachis increased by 6% with the medium shoot density treatment, compared to low and high shoot density treatments.
Box-pruned Syrah vines had 11% less berry volume than spur-pruned vines. Increasing the shoot density per foot of vine-row with medium and high shoot density treatments decreased berry volume by 10% and 13%, compared to low shoot density treatment, respectively.
Effect of mechanical canopy management on yield Mechanical boxpruning of Syrah vines produced higher yields (16%) with smaller berry size (12%) compared to vines spur-pruned by hand. The difference in yield came from the number of clusters that were borne on the shoots retained.
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