Palissage is a novel, promising alternative to hedging that has only recently been studied. It consists of either Shoot Wrap (shoots are wrapped on the top catch wire) or Shoot Tuck (shoots are tucked back into the catch wires). However, timing of palissage technique application has never been evaluated prior to this study, so timing of palissage technique applications were evaluated at two timings (Timing One = 30 cm and Timing Two = 90 cm above the top catch wire). Vine physiological effects such as canopy density parameters, fruit parameters, and spray penetration to the clusters, were investigated in response to palissage techniques compared to the hedging technique as control.
Cluster compaction, or the number of berries per cm, was reduced by Shoot Wrap at Timing One by 1.4 berries per cm rachis. Palissage techniques also decreased lateral emergence in the fruit zone by 14 lateral shoots between the hedged Control and Shoot Wrap, regardless of timing. These findings suggested that the retaining of shoot tips, a strong sink, may have reduced carbohydrate re-translocation to support lateral shoot growth and berry growth. Yields were impacted by feeding or downy mildew damage, but number of clusters was reduced by technique with Shoot Wrap having the fewest clusters especially at Timing One. There seemed to be no difference in fruit composition or many canopy density parameters. Neither spray penetration to the clusters nor downy mildew incidence or severity differed between techniques or timing. These findings suggesting that carbohydrate translocation was more impacted earlier than later in the growing season by canopy management practices but vines may have been able to recover with bigger and/or more photosynthetically efficient leaves, and/or sink priority changes from vegetative organs to reproductive organs (fruit). Still, palissage has the potential to be used by growers in place of hedging, with fewer laterals emerging especially in the fruit zone, potentially improving canopy microclimate and possibly, cluster rot.
1. To determine whether the timing (early vs. late) and method (shoot tucking vs. shoot wrapping) of palissage compared to hedging will reduce vegetative growth (lateral emergence) and vigor, reduce cluster shading, reduce disease incidence and cluster compactness, and improve fungicide penetration in Cabernet Franc winegrapes.
2. To evaluate carry-over effects of palissage on the same site established in the cool and wet Northeast through 2019 as a sustainable alternative to hedging.
3. Develop a cost analysis to determine the economic impact of palissage compared to hedging.
4. Educate the New York State winegrape industry about the potential of palissage through Appellation Cornell newsletters, tailgate talks with growers, and grower conferences.
Growing Vitis vinifera winegrapes (i.e. commonly-grown European cultivars such as Riesling and Cabernet Franc) in the Northeast US comes with many challenges. Several of these challenges include cultivars’ susceptibility to fungal diseases including cluster rot and Botrytis cinerea and excessive vine vigor due to the region’s cool and wet climate and high organic matter soils. Excessive vine vigor (long internodes, strong lateral growth, and large leaves) can lead to longer periods of leaf and fruit wetness and limited light penetration in the fruiting zone, lower spray penetration, and a humid microclimate, all of which lead to more and longer disease infection periods.
Current canopy management practices exacerbate the consequences of excessive vigor (Wolf 2008). To limit excessive vegetative growth, winegrape growers hedge their canopies by cutting off shoot tips intermittently throughout the growing season in vertically shoot positioned training systems (Wolf 2008). While the canopy density is temporarily reduced through hedging, hedging ultimately promotes lateral emergence and extension in the fruiting zone especially when applied early (Reynolds et al 1989; Molitor et al 2015; France 2017). These emerging lateral shoots increase the duration of cluster wetness following periods of rain, shade the fruit, and reduce spray penetration to the clusters. Hedging also enhances the transfer of assimilates to the developing inflorescences, which is often linked to compact clusters (Molitor et al 2015). Compact clusters are highly correlated with Botrytis cinerea (Vasconcelos et al 2000).
As a different approach to hedging, “palissage” has been investigated by the Vanden Heuvel research group at Cornell, following feedback from growers. When palissage is applied, for Shoot Wrap, shoots are either wrapped around the top catch wire, or for Shoot Tuck, shoots are tucked back down into the canopy (Figure 1). Preliminary results were promising; lateral emergence and cluster compaction were reduced. Earlier cessation of shoot growth and reduced lateral emergence were also reported by growers, eliminating the need for leaf removal to open up the canopy (Vanden Heuvel, unpublished data). Palissage has the potential to improve light interception to the clusters and wine quality. Given a significant reduction in disease incidence on palissaged vines in contrast to hedged vines, palissage can be incorporated in the grower’s disease management program, reducing the need for fungicides (France 2017).
Materials and methods:
The study was established in growing season 2016 on Vitis vinifera Cabernet Franc cl. 4 grafted on 3309c rootstocks located in a 0.25 ha research vineyard in Lansing, NY with two experimental units per row as described in the proposal. Three shoot tip management methods (shoot wrapping, shoot tucking, hedging (control)) were evaluated in a randomized complete block design in a factorial with two timings of treatment application: early (shoots reach 30 cm above the top wire) and late (shoots reach 90 cm above the top wire).
Shoot length of lateral shoots of 32 shoots per experimental unit in the fruiting zone, mid-canopy, and upper canopy for all treatments, were quantified as detailed in the proposal in 2019. Canopy structure (i.e., leaf and cluster light interception) was analyzed on each vine using enhanced point quadrat analysis at pre-harvest as described in the proposal (Meyers and Vanden Heuvel 2008). Leaf area was taken on both primary and lateral leaves on one shoot per vine, or eight shoots per experimental unit.
Following spray application of water at veraison, when vines in this region are most susceptible to cluster rot, spray penetration to clusters was evaluated with spray penetration cards, by counting the number of grids that had more than 50% coverage, with blue color indicating spray coverage and yellow color indicating no spray coverage (Salyani et al 2013).
At harvest, lateral shoots were counted and measured in the fruit zone, mid canopy, and upper canopy. Grapes from each experimental unit were harvested for yield per panel which consisted of four vines, or half an experimental unit, due to some animal feeding damage on October 15, 2019. Twenty clusters per experimental unit were collected and analyzed for pH, Brix, titratable acidity, and yeast assimilable nitrogen, using standard procedures (France 2017).
Following harvest, when cane-pruning dormant vines to 40 nodes, weights of fruiting wood from the previous growing season was collected for each vine in each experimental unit for all treatments as discussed in the proposal.
Figure 1: Diagram of palissage techniques and hedging.
Figure 2: The treatments applied: Control (Hedged), Shoot Tuck, and Shoot Wrap
Fall and Winter 2019
Statistical analysis and presentation of data and results from previous and current growing seasons for presentation at the Business, Enology, and Viticulture conference in March of 2020.
Summarize data and results from all growing seasons evaluated to be shared in Cornell newsletters and presented at several conferences including the American Society for Viticulture and Enology –Eastern section conference.
Submit manuscript to the American Society of Enology and Viticulture journal for publication.
Education & Outreach Activities and Participation Summary
This project is being analyzed and summarized. Parts of the findings were shared at the American Society of Enology and Viticulture – Eastern Section conference in 2018. The project will continue to be shared with the scientific and industry communities through publications, meetings with growers, and conferences.
Lateral emergence was reduced by 27% by shoot wrap, regardless of timing in the fruit zone, both in length and in number per vine, potential improving cluster microclimate and reducing cluster rot disease incidence and severity. Cluster compaction, or number of berries per cm, was also reduced by technique only, potentially reducing cluster rot. Spray penetration, using water, to the fruit zone is improved with both palissage techniques, at Timing 2. Shoot Tuck exacerbated Downy Mildew incidence and both Shoot Wrap and Shoot Tuck had slightly higher Downy mildew severity than Control at the earlier timing. This year was a very wet year, compared to previous years, which may have worsened downy mildew incidence and severity.
However, some canopy metrics were slightly improved with palissage techniques with slightly higher leaf and cluster exposure flux availability in Shoot Wrap, potentially increasing light penetration and aeration to the clusters and leaves. There were also reductions in percent interior leaves in Shoot Wrap, possibly meaning higher photosynthesizing and potentially increasing reserves for the fruit and roots to improve the vine’s cold hardiness and percent budbreak. Yields were higher by 1 kg in the Shoot Tuck technique but did not differ greatly between Shoot Wrap and Control
Palissage has the potential to be used by growers in place of hedging as it did not require more than one trip through the vineyard due to successful reductions in lateral emergence and cluster compaction, improving spray penetration, and thus, requiring less fungicide spray and increasing the sustainability of vineyard management.
Pruning weights from 2018 will be collected in March or April of 2019 during pruning to quantify the ratio of vegetative growth by ways of pruning weights to yield (crop load) and observe if palissage techniques and/or timing will improve the ratio. This project will be also evaluated for one more growing season. It would make sense to repeat timing trials on tight clustered cultivars such as Riesling and Pinot Noir to observe impact of timing of palissage application on Botrytis cinereaand other cluster rots as that was something not observed in the Cabernet Franc vines used for this study. Mechanisms behind the reductions in lateral emergence, cluster compaction, and increases in yeast assimilable nitrogen, an important element for vinification ought to be explored in depth to better understand how to improve palissage as a promising tool for growers.