Issue link: https://read.dmtmag.com/i/450509
www.goodfruit.com Good Fruit Grower FEBRUARY 1, 2015 37 Alberto Dorigoni is considering shorter trees grown somewhat like vines. by Richard Lehnert A lberto Dorigoni's research on apple orchard design in northern Italy is having an impact well outside of his area, including in the United States. Even as his research goes on, a few growers in the Great Lakes region are adopting his fruiting wall concept, including the use of mechanical hedging with sick- lebar mowers to create them. Dorigoni's work is infl uencing Dr. Terence Robinson at Cornell University, and Robinson has a large following of growers and tree fruit educators in New York and Michigan who believe this work is on the cutting edge of future orchard design. In November, growers traveling on the International Fruit Tree Association's study tour to Italy saw Dorigoni's work fi rsthand. There, on about 30 acres in a valley surrounded by Alpine moun- tains, he has rows and rows of trees for evaluating novel orchard design concepts. "We are looking at ways to be more sustainable," Dorigoni said. "We want to use less labor, simpler pruning and thinning methods, and fewer chemical inputs." In Italy and across Europe, herbicides such as paraquat can no longer be used, nor can car- baryl (Sevin) for thinning. Dorigoni's research takes place at the Institute of Agriculture at San Michele All'Adige experimental farm in Trento province south of Bolzano. There, he studies such things as fruiting walls of varying heights, tree spacings, and alley widths; multi-leader trees; mechanical pruning and hedging; mechanical thinning; alternative ways of spraying, such as tunnel sprayers to reduce drift and make more effective use of spray materials; and use of nets—to ward off not only hail but insects—and to create shade or exclude pollinators to affect fruit set without hand or chemical thinning. He has also partnered with Cornell University entomologist Art Agnello (and indirectly with researchers in Washington State and Michigan) who are studying the solid-set canopy spray deliv- ery (SSCD) system. In the SSCD, trees are sprayed with lines and nozzles permanently installed in the tree canopy. That could take sprayers out of orchards. Past platforms While many growers are just now moving toward greater use of platforms, Dorigoni said he is moving past platforms. While he agrees that very tall fruiting walls are "an option," he is also looking at very short trees, grown in much narrower rows—"more vineyard-looking orchards." With shorter trees, it becomes easier to use nets to do things besides ward off hail. They can be used to create shade to make apples easier to thin; they can be used to exclude insects such as codling moth; they can be used to exclude bees and other polli- nators, so thinning can be achieved by allowing only the earliest blooms to be pollinated and then covering the trees with nets. Every foot that trees are shortened allows alleys to be a foot narrower. He thinks an alley a meter and a half wide—fi ve feet— would be adequate. Multiple trunks About 15 years ago, an Italian nursery, Mazzoni, developed bi-axis trees and called them Bibaum—two trees on one root. Not only should it be somewhat cheaper to plant one tree where two were planted before, the double leaders provided a new option for vigor control. Dorigoni has taken that idea several steps further. "The num- ber of leaders can be a variable to use according to the strength of the soil and the variety," he said. He has developed trees with three leaders, by training two side limbs off a central leader. He has developed four leaders by split- ting two bi-axis leaders. In his experimental plantings, he has trees that look like the Upright Fruiting Offshoot cherry trees developed at Washington State University and being tested across the United States now. The two trunks on a bi-axis apple tree are bent over to hori- zontal and the limbs that grow upward from those trunks bear the fruit. "Treat them as individual small spindles," Dorigoni said. Renewal pruning is used to take out the largest limbs and allow new, smaller upright limbs to grow in their place. Dorigoni planted Red Delicious on the stronger rootstock M.106 and con- trolled the vigor with up to eight leaders growing upright. "With M.106 and six leaders, we achieved pedestrian-size orchards with trees 2.4 meters (8 feet) tall," he said. With multiple leaders, Dorigoni wants the buds set close to the graft union. "Start as low as possible," he said. "The style is similar to the old palmette." Dorigoni's initial work on converting spindle trees into fruiting EXPANDS Fruiting wall concept Rome Venice Milan SWITZERLAND AUSTRIA SLOVENIA CROATIA FRANCE ITALY Venice SLOVENIA SLOVENIA CROATIA CROATIA ITALY ITALY SOUTH TYROL (SUDTIROL) Merano Bolzano PHOTOS BY RICHARD LEHNERT/GOOD FRUIT GROWER Alberto Dorigoni takes IFTA growers through his extensive trials. These bi-axis trees were converted over to multiple leaders by bending them and allowing shoots to develop upward. Think of them as multiple spindles, he said. "We are looking at ways to be more sustainable. We want to use less labor, simpler pruning and thinning methods, and fewer chemical inputs." — Alberto Dorigoni