Issue link: http://read.dmtmag.com/i/331109
www.goodfruit.com GOOD FRUIT GROWER JULY 2014 25 Early leaf removal could change cluster structure; late can delay ripening. by Melissa Hansen I talian scientists are studying mechanical pruning and leaf removal as a way to increase wine grape yields, reduce labor costs, improve cluster structure, and delay ripening—all without negatively affecting fruit quality. Recent wine trends in Italy have changed industry dynamics and made grower profitability all the more important, says Dr. Stefano Poni, director of the Institute of Fruit and Viticulture at the Sacred Heart Catholic University in Piacenza, Italy. Accord- ing to Poni, in the last 25 years, Italian wine grape acreage has decreased by nearly 40 percent, from 2.4 million to 1.5 million acres, per capita wine consumption in Italy dropped from 24 to 10 gallons, and average farm size has doubled from 2.4 to 4.1 acres. "Terroir is not enough anymore for us to stay competitive in the wine market," he said to Pacific Northwest vintners and growers. "To be profitable, we need to reduce grower costs, remunerate growers for yields, and be envi- ronmentally sustainable." Poni, a speaker at the Washington Association of Wine Grape Growers's annual meeting in February, shared results of his vine efficiency and canopy management research work that is changing the mindset of Italian growers. It's no easy feat to persuade growers who are steeped in centuries-old tradition and culture to adopt mechanization. "How do you convince growers who are used to doing everything by hand that mechanically pruned vines can be as efficient as their nice-looking, hand-pruned vines?" he asked. Moving to mechanization Mechanization starts with the trellis system, Poni said. "Italians are known for having a lot of fantasies—food, shoes, politicians—and also in our grapevine training systems. We have 43 different trellis systems in our text- books, 12 that are popular. How can we think of vine mechanization if we have so many trellises?" To address the mechanization issue, scientists had to come up with a new trellis system suitable for mechanical pruners, and other equipment. A new single, high-wire trellis was developed, featuring a spur-pruned cordon with a single wire 1.4 to 1.7 meters (54 to 70 inches) off the ground. In addition to being suitable to mechanization, Poni said the new system has improved the cluster microcli- mate and canopy efficiency. Scientists used special plas- tic bags to envelop the vine, a technique used to measure the whole canopy gas exchange. They compared the new single high wire to the vertical shoot position trellis and found the VSP had a 26 percent lower photosynthetic rate. "The reduction in photosynthesis was due to reduced light inside the canopy. With the VSP, we compressed the canopy between the catch wires too much," he said, add- ing that the new high-wire system allows diffused light and sun flecks into the canopy. Summer temperatures in Italy have increased in recent years, and he believes the new trellis will be beneficial for both white and red varieties because it will provide sunburn protection, yet still allow enough light interception. Mechanical pruning Big labor savings can come from using mechanical pruners to remove wood above the cordon, but shoots need to be upright so machines can reach the wood. Cabernet Sauvignon grows naturally upright, Trebbiano grows downward, and Chardonnay is like "messy hair" that goes every which way, said Poni, who had to find a way to correct downward shoot behavior. By mechanically shoot thinning early in the season—at prebloom stage—he was able to induce a more erect growth pattern. Grapes Leaf removal BENEFITS These Grenache grapes in the Rioja region of Spain show the effects of early leaf removal. PHOTOS BY STEFANO PONI Equipment Company Equipment Company CALIFORNIA 509-952-9488 PASCO 509-544-6678 WALLA WALLA 509-525-4550 UNION GAP 509-248-8411 GEORGE 509-785-2595 CLE ELUM 509-674-4544 SUNNYSIDE 509-839-2066 See Your Nearest Blueline Equipment Dealer Today . . . Designed for the Modern High Density Orchard All "Perfect" rotary mowers comply with the highest level of current requirements in modern orchards and vineyards. In order to prevent damage to low hanging branches and fruit the T-models have a low, streamline profile and round sides Technical Specifications T-155 T-180 T-200 T-225 T-250 T-290 Cutting width cm/inch 155 / 5'2" 180 / 5'11" 200 / 6'7" 225 / 7'5" 250 / 8'2" 290 / 9'6" Min. power required at 540 rpm of pto kW/hp 16 / 22 18 / 25 22 / 30 26 / 35 29 / 40 33 / 45 Numbe of blades 3 3 3 3 3 3 Total width cm/inch 160 /5'3" 185 /6'1" 205 /6'9" 230 /7'7" 255 /8'4" 295 /9'8"