Issue link: http://read.dmtmag.com/i/657340
www.goodfruit.com Good Fruit Grower APRIL 1, 2016 31 Tip for growers D r. Letizia Rocchi's research at the University of Milan also showed that the timing of leaf removal in Chardonnay and Riesling grapes could be key to reducing the appearance of brown color in berry skin. In Chardonnay, growers are advised to avoid any leaf removal in the morning and to remove leaves in the afternoon. Because Riesling is more susceptible to sunburn in the afternoon, growers should do leaf removal during the early morning, if necessary. This research was carried out under the COST Action and InnoVine project, a European collab- orative project involving 27 partners from seven European countries. bigger canopy, better protecting white wine grapes from overexposure to sun. They will continue their study this year. Sun exposure and skin phenolics As part of this project, Dr. Letizia Rocchi, then a visit- ing doctoral student from the University of Milan, Italy, also studied the phenolics in Chardonnay and Riesling grapes in response to sunlight exposure under two irri- gation regimes. One featured full irrigation, where vines were irrigated to replace 100 percent crop evapotranspiration from fruit set to harvest, with no water stress imposed. The other employed deficit irrigation where vines were irrigated to maintain a moderate water stress from fruit set to har- vest. She also evaluated berries exposed to direct sunlight and others totally shaded from sunlight. Rocchi said high light regimes potentially stimulated a protection mechanism in the skin, increasing flavonols over the season. Flavanols also had their highest con- centration in the sun; it could be speculated a possible involvement of these molecules in the photo-protection mechanisms of the berry, the study showed. Hot tempera- tures did not affect biosynthesis of flavanols, but could have had a role in significantly reduced flavanol formation in Chardonnay, especially at harvest, Rocchi said. Flavonols, found in grape skins, contribute to bit- terness and protect fruit from sunburn. Flavanols, meanwhile, polymerize — attach to each other to get bigger — and get more astringent as they enlarge. They also contribute to bitterness and to tannins in wine. Overall, the research showed that overexposure of clusters to sunlight led to higher concentration of com- pounds that potentially elicit bitterness and astringency in the final wine. No effects on flavonol and flavanol accumulation were directly due to the irrigation regimes in either cultivar (Chardonnay and Riesling). However, leaf area reduction as a consequence of water deficit, thus irriga- tion regime management, seems to indirectly affect the flavanols and flavonols by providing high exposure of fruit, also generating sunburn appearance. The results suggest that when planting vineyards growers should consider orientation to avoid peak sun exposure; also, to avoid trellis systems that have exces- sive fruit exposure; to avoid severe leaf removal; and to manage the water deficit, thus irrigation regimes, to avoid an excessive canopy reduction, which could gen- erate excessive cluster exposures. Collaborating on the project were Keller, Smithyman, Dr. Jim Harbertson, WSU enologist, and Professor Osvaldo Failla of the University of Milan. The Washington Grape and Wine Research Program, the Washington Wine Commission and a WSDA Specialty Crop Block Grant Program funded the research. • © 2016, Trécé Inc., Adair, OK USA • TRECE, PHEROCON and CIDETRAK are registered trademarks of Trece, Inc., Adair, OK USA TRE-0869 PLEASE: ALWAYS READ THE LABEL DECREASES DAMAGE! 40% Average Reduction Compared to Insecticide Alone. * INSEC T PHEROMONE & KAIROMONE SYSTEMS INCORPORATED ® Your Edge – And Ours – Is Knowledge. CIDETRAK ® DA MEC ™ contains a novel, patented kairomone in a micro-encapsulated liquid formulation that influences the behavior of adult and larval Codling Moth, resulting in significant enhancement of the control of Codling Moth larvae when tank mixed with various insecticides. Additionally, Codling Moth adult control is significantly enhanced when mixed indirectly with airborne Codling Moth pheromone applied as a mating disruption treatment. • What it does: Disrupts oviposition. Changes larval behavior: Stops/delays locating fruit; stops/delays fruit entry and reduces damage. • How to use it: Simply tank mix with each insecticide application. • Longevity: More than 14 days following application. Contact your local supplier and order now. Visit our website: www.trece.com or call 1- 866 -785-1313. ENHANCED CODLING MOTH LARVAL CONTROL MICRO-ENCAPSULATED SPRAYABLE! *Based on USDA analysis global data base. Available in 10, 20 and 40 acre container sizes!