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.
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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.
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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
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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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