penn state research trials on leaf removal · 2020. 6. 12. · cluster weight (g) # berry/ cluster...
TRANSCRIPT
Effects on bunch rot
Effects on yield
Effects on fruit composition
Penn State research trials on leaf removal
Bryan Hed – Grape pathologist
Penn State research trials on leaf removal across PA
• VarietiesoRiesling
oPinot noir
oPinot grigio
oGrüner Veltliner
oVignoles
• Multi-year studies
Can leaf removal be mechanized while maintaining the same benefits of manual application?
Pulsed-air leaf remover (Collard, Bouzy, France)
Tractor speed: 1.4 mphHead speed was set at 850 rpm
RieslingControl Hand leaf removal Mechanical leaf removal
Leaf area mechanically removed with the machine was on average 51% of that removed by hand
Control vines, no-leaf removal
Riesling vines at harvest
Both hand and mechanical leaf removal improved fruit sunlight exposure
Hand leaf removal Mechanical leaf removal
Leaf removal trials in Erie county
Photo credit B. Hed
Blueline Deleafer, Blueline Manufacturing Company Inc, Yakima, WA
Pinot Grigio (2018) – Erie county
Photos credit B. Hed
Control vines, no-leaf removal Mechanical leaf removal
Effects on bunch rot
Effects on yield
Effects on fruit composition
Penn State research trials on leaf removal
Bryan Hed – Grape pathologist
Carbohydrate limitation
Can reduce fruit set (percentage of flowers that become fruit)
Decrease the number of berries per cluster and cluster compactness
Removing basal leaves pre-bloom
‘Early’ leaf removal (pre-bloom/ trace bloom) affects cluster morphology
The compactness of the cluster favors the colonization and spread of bunch rot organisms within the cluster
berry-berry contact
Berry number
Early leaf removal
Spread of bunch rot
No-early leaf removal
Early leaf removal
Photo credit: M. Smith
Pre-bloom 4 (2.12 t/acre) Pre-bloom 8 (1.17 t/acre) Post-fruit set 6 (3.52 t/acre)
Timing (and extent) is everything…
Crop yield can be affected by the number of leaves removed before bloom
Cabernet Sauvignon (VA)
Source: Cain Hickey
Effects on bunch rot
Effects on yield
Effects on fruit composition
Research trials on leaf removal
Pinot Grigio (2017 and 2018)
Treatment Incidence of rot infection
(% clusters)
2017 2018
Control - no leaf removal 44.0 30.0
Hand leaf rem. – pre-bloom 8.5 4.0
Mechanical leaf rem. – pre-bloom 13.0 9.0
Mechanical leaf rem. – fruit set 16.0 9.0
Incidence = Percentage of clusters with bunch rot
Treatment Severity of bunch rot
(% cluster area )
2017 2018
Control - no leaf removal 11.6 7.5
Hand leaf rem. – pre-bloom 1.2 0.9
Mechanical leaf rem. – pre-bloom 3.0 2.7
Mechanical leaf rem. - fruit set 2.2 1.9
Severity = percentage of the cluster’s area affected
Pinot Grigio (2017 and 2018)
Control Hand-LR Mechanical-LR
Photo credit: B. Hed
Cluster weight (g)
# Berry/cluster
Severity of bunch rot
(% area)
Control - no leaf removal 127.8 97.8 11.59
Hand leaf rem. – pre-bloom 108.4 73.2 1.23
Mechanical leaf rem. – pre-bloom 107.8 74.5 2.95
Mechanical leaf rem. - fruit set 127.9 101.4 2.17
→ Leaf removal before bloom: Vines have smaller and less compact clusters → Leaf removal reduced bunch rot regardless of timing or method
Pinot grigio (2017)
Cabernet Sauvignon Botrytis – in VA
Botrytis incidence (%)
No leaf removal 18.5
Pre-bloom - 4 0.0
Pre-bloom - 8 0.0
No leaf removal 28.8
Post-fruit set - 6 6.4
Hickey et al. (2018) - Catalyst
Effects on bunch rot
Effects on yield
Effects on fruit composition
Research trials on leaf removal
Treatment Titratable acidity
(g/L)2017 2018
Control - no leaf removal 5.4 6.0
Hand leaf rem. – pre-bloom 4.8 4.3
Mechanical leaf rem. – pre-bloom 4.8 4.9
Mechanical leaf rem. – fruit set 4.6 4.5
Pinot noir (2017 and 2018)
Fruit ripeness parameters →most consistent effect across studies was a reduction in TA
Sugars and acids – Merlot in NC
Brix: TA ratio
TA (g/L)
No Leaf Removal 4.4 4.2
Leaf Removal 4.8 3.8
Chardonnay
High Brix: TALow Brix: TA
Source: Cain Hickey
Anthocyanins – Cabernet Sauvignon in VA
Total grape anthocyanins (mg / g berry)
2013 2014 2015
NO 0.94 1.11 b 0.83 b
PB-4 1.00 1.22 a 1.00 a
PB-8 1.02 1.12 b 1.02 a
Hickey and Wolf (2018)
Total grape anthocyanins (mg / g berry)
2013 2014 2015
EAST 1.02 1.15 0.94
WEST 0.96 1.16 0.95
Take home message
• Regardless of timing and method, leaf removal reduced bunch rot compared with no leaf removal
• Pre-bloom leaf removal should be judiciously used as it can result in crop reduction
• Basic juice chemistry: the most consistent effect of leaf removal was lower juice acidity
• Mechanized leaf removal mimicked most of the effects of the manual application
Acknowledgments
Grower cooperators
Bryan Hed
Penn State Wine and Grape Team
Penn State Viticulture research lab
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