by Tamara Scully
Cornell Cooperative Extension’s Agriculture and Food Systems In-Service Conference, held in early November, featured programs in every aspect of agriculture. The Cornell Recent Advances in Viticulture and Enology (CRAVE) Conference, held during the In-Service Conference, featured short segments from graduate students involved in research projects involving all aspects for grape and wine production.
Canopy Management
Increasing vineyard yield and health, while reducing labor and input, is always on the minds of growers. Graduate student Justin France presented data on palissage, a canopy management technique, in Northeast vineyards. Palissage is studied as an alternative to the more commonly employed hedging.
Used to control vigor, increase yield, improve canopy microclimate and increase fruit and wine quality, hedging also stimulates growth, causing excessive time and labor. Hedging often results in rapid lateral growth. These laterals then need to be removed throughout the season. Leaf growth can also be increased via hedging, causing canopy concerns. Palissage, a technique in which actively growing vines are tucked back in to the canopy, could provide canopy management without the undesirable growth of laterals.
France, working with Dr. Justine Vanden Heuval, conducted experiments studying two separate palissage practices, shoot wrap and shoot tuck, as well as controls using typical mechanical hedging. The studies were conducted on two commercial vineyards — one in the Finger Lakes region and one on Long Island — as well as at Cornell’s orchards in Lansing.
Shoot wrapping involves taking the active shoot tip and wrapping it around the training wire, continuing this on all vines going down the row. It is easiest to do on shorter canes, as less wrapping is needed.
Shoot tucking requires pulling the tip of the active vine back into the canopy, bending it down towards the ground in a “candy cane” type form, France said. This technique may cause more lateral growth than shoot wrapping.
The various experimental sites incorporated different techniques. In the Finger Lakes, King Ferry Winery — which has been experimenting on their own for numerous years — utilized shoot tucking, shoot wrapping, and mechanical hedging on three different treatment areas of Riesling grapes.
A Long Island commercial vineyard, growing Cabernet grapes, had a control block where their normal mechanical hedging was used, and a research block using shoot tucking.
At the Lansing orchards, a 144 plant block of Cabernet Franc grapes was divided into shoot wrapping, shoot tucking, and mechanical hedging blocks. Each block was further divided, offering data on two different timing protocols for the techniques.
In the Lansing location, no noticeable change in yield was noted between the techniques. Lower cluster compaction with palissage techniques, with fewer berries per cluster, did offer the potential of decreasing disease severity, as less compacted clusters are not as friendly an environment for pathogens. Clusters on vine undergoing palissage were found to enter veraison earlier than on those mechanically hedged.
The Riesling grapes at King Ferry Winery showed that hedging did stimulate lateral growth, while “shoot wrap had less lateral emergence in the fruiting zone,” France said. “Treatments actually redirect overall lateral emergence.”
The research data also indicated that there was no impact to Brix, or ph between treatment methods. Tannic acid was found to be “slightly elevated” in palissaged vines.
Anecdotally, growers indicated that vine size is reduced via palissage training, without any impact on fruit yield. Because less labor is needed throughout the growing season, compared to hedging, palissage saves time and money.
“Palissage does take longer to do than hedging, by hand, but you only have to do it once,” France emphasized.
National Clean Plant Program
The wine industry has a 160 billion dollar economic impact in the United States alone. Grapevine leaf roll disease is a global concern with the potential to severely curtail the industry’s capacity. Infected vines cannot be cured, and destruction is the only way to achieve any control. Rootstocks can be infected, so top grafting is not an option. Spread of the disease is rampant. Using clean planting stock is the only reliable method of reducing the spread of crop diseases that cannot otherwise be eradicated.
The National Clean Plants Network has five Grape Centers, established in 2002, at Universities across the United States — Cornell, UC Davis, Washington State, Michigan State, and Florida A&M. Developed to insure a clean supply of plant material to combat the economic loss from disease concerns, these Grape Centers focus on propagating clean stock for nurseries and growers.
Jason Troendle, working with others at Cornell in Applied Economics and Management, has calculated benefit-to-cost ratios of the Federal Government’s investment in the Grape National Clean Plant Network’s centers, focusing primarily at UC Davis.
“How much of clean plant material has been adopted and is currently in the field being grown?” was the first question to answer, Troendle said.
UC Davis began making cuttings of clean plant material in 2005. From each cutting, three plants were propagated and grown for two years. The third year, plants could be distributed on the nursery level, where mother blocks were grown. Each mother block could generate 50 cuttings annually for distribution to vineyards. After three years, these Clean Plant vines would be producing a crop. Calculations do take into consideration that some clean plantings will become infected with the virus each year, resulting in reduced yields, labor and other costs.
The six-year “delayed process” from virus-free cutting to vineyard bearing fruit, is assumed to have a 10 percent loss at each step of the process. It would have begun to show real economic benefits by 2011, with a large increase in benefits in 2014, according to Troendle’s calculations. Until then, the costs associated with the program outweighed any benefits, as plants were propagated and established.
The cost of the UC Davis Grape Center’s operation, since 2002, was 1.5 million, in “real 2002 dollars,” Troendle said. Projected out to 2026, the program costs would be 2.5 million dollars. “Keep in mind this is an average 160 billion dollar annual industry.”
Troendle’s preliminary calculations indicate that 8.8 billion dollars in total benefits, over 25 years, will be generated from the Clean Plant Network’s UC Davis Grape Center. The team will assess the impact of New York’s Cornell Grape Center as well. Positive economic benefits are expected to begin here in 2021.
“Overall, it seems the benefits outweight the costs,” Troendle concluded.