Issue link: https://read.dmtmag.com/i/657340
www.goodfruit.com Good Fruit Grower APRIL 1, 2016 29 G rowers have employed deficit irrigation in red wine grapes for years, knowing that smaller berries result in a higher propor- tion of berry skins favorable for tannins and other phenolic compounds that improve wine flavor and color. What about white wine grapes? White wine grapes are not fermented with the skins, and too many phenolic compounds generally make the wine more astringent and increase instability during aging anyway. They also are more susceptible to sun- burn, which can increase bitterness. For that reason, a deficit irrigation strategy that is beneficial to reds may not be suitable to whites. Researchers at Wash- ington State University are examining whether white wine grapes could receive less water through a technique called partial root-zone drying and still maintain the quality of the grapes and wine. Results from the first two years of study are promising. "The potential benefit is that it seems like partial root- zone drying is a technique that does not reduce berry size or yield as much as conventional deficit irrigation. We think that will be beneficial especially to white wine grapes," Dr. Yun Zhang, a postdoctoral research associate at WSU's Irrigated Agriculture Research and Extension Center in Prosser, Washington, told Good Fruit Grower. The technique Both irrigation strategies impose some water deficit to constrain canopy growth and control vigor and berry size, though they differ in their approach. Regulated deficit irrigation imposes a soil water deficit over time and is applied at specific points in the growing season. It results in a plant-water deficit and reduces berry size and yield. Partial root-zone drying, a technique developed in Australia, imposes a soil water deficit spatially and, in this case, was applied from fruit set to harvest — essen- tially drying out one side of the root zone while the other side is being irrigated, supplying the vine enough water for growth. With two drip irrigation lines running on both sides of the vine, the technique is more expensive. However, by alternating which side receives irrigation, the vines are tricked into thinking that there is soil water deficit, reducing their canopy growth, and berry size and yield reduction are less severe. "It has enough water to support growth and photo- synthesis," Zhang said. "Meanwhile, the drying part of the root zone generates hydraulic and chemical signals to trick the vine." "Now we're seeing the right way of watering white varieties. We're working to be more efficient, maybe use less water and still have high quality." —Russell Smithyman Research shows growers can conserve water while still maintaining quality grapes. by Shannon Dininny WhItes ProTree Nursery provides exceptional customer service and high-quality trees at a fair price. These are the reasons why our customers keep coming back year after year. We have over 40 years of experience in selecting the best root stocks matched with top varieties. We provide hearty trees and a great value. No bells… no whistles… just a business built on exceeding our customers' expectations. Call ProTree Nursery today — get the value you deserve in each and every tree. 10500 Brentwood Blvd., Brentwood, CA 94513 800.634.1671 or 925.634.2191 (Alison Clegg or Richard Chavez) 877.457.6901 (Henry Sanguinetti) M E M B E R O F w w w . p r o t r e e n u r s e r y. c o m Value from the ground up. Apples Aztec Fuji ® (DT-2 cv) Banning Red Fuji (USPP 16,624 P2) Buckeye ® Gala (USPP 10,840) Cosmic Crisp™ 'WA 38' cv (USPP 24,210) Firestorm™ Honeycrisp Honeycrisp™ (USPP 7197) Lady in Red * (USPP 18,787) Royal Red Honeycrisp ® (USPP 22,244) September Wonder™ Fuji (USPP 11,193) Ultima™ Gala (USPP 13,753 P2) Available on B10 ® , B-118, EMLA, Geneva ® , M-9 T337, NIC -29™, or Pajam #2. ** * Trademark license for Pink Lady ® brand available upon request. Cherries Benton™ Bing Black Tart BlackPearl ® Brooks™ BurgundyPearl ® Chelan™ Coral Champagne Cristalina™ EbonyPearl ® Available on Colt, Gisela ® , Krymsk ® , Mahaleb, or Mazzard. * * ** Not all varieties are available on all rootstocks. Call for specific grafting information. Lapins RadiancePearl ® Rainier Selah™ Skeena™ Sweetheart™ Tamora Tulare™ Vans NEW! NEW!