On Michigan’s Fruit Ridge north of Grand Rapids, where half the state’s 25 million bushels of apples are grown, Cornell University horticulturist Dr. Terence Robinson is held in very high regard.
Most of the growers have been planting apples following his tall spindle design, and they take every opportunity to learn and refine their techniques of trellis building, feathered tree planting, no heading, limb tying, and renewal pruning. And as Robinson plunges into new territory, they listen and are quick to adopt.
Robinson was the guest of honor during the second annual Ridgefest presented in early August by the Michigan Pomesters and attended by 200 growers. He is the keynote speaker on December 2 at the Washington State Horticultural Association meeting in Wenatchee.
Robinson’s latest idea: In year five, convert those tall spindle orchards into fruiting walls using mechanical hedging in summer to narrow the trees to three feet thick at the base, two feet thick at the top.
A fear, however, is that fireblight could infect the trees through the cut shoots, Robinson said. “I wouldn’t try it in orchards with a history of fireblight.”
Michigan extension fruit educator Phil Schwallier is a strong advocate of Robinson’s tall spindle training system. He convinced the folks at Thome Orchards in Comstock ParkHarold and Joann, their son, Steve, his wife, Missy, and grandson, Mitchto hedge one row of trees on July 1 and another on August 1. The trees are Brookfield Gala in their seventh leaf. Steve admitted to having some doubts, one of which he expressed with an application of antibiotic after hedging “just in case” fireblight might be in the orchard.
They used a double-action (reciprocating) sickle bar hedger developed by Phil Brown Welding, located only about three miles from their orchard.
“You need to do this,” Schwallier told growers about hedging. “This is your future here. Take a good look at it. Everybody will be doing this in the next five to ten years.”
Schwallier and Dr. Ron Perry introduced other Michigan growers to the concept during two field days at the Clarksville Horticultural Experiment Station earlier in the summer. Perry used an ordinary gas-powered, handheld garden hedge pruner to show everybody how easy it was and how quickly results were visible.
Robinson said he was introduced to the hedging concept in Europe about five years ago, but the Europeans don’t have to deal with fireblight, and he was fearful of trying it in the Northeast or the Great Lakes region.
“Studies by Sherm Thomson in Utah showed that the summer heat really slows fireblight down,” Robinson said, and that encouraged him to put trials together in New York. Last winter, Dr. Alberto Dorigoni, a pomologist in Italy’s South Tyrol region, came to Boston for the winter meeting of the International Fruit Tree Association, where he explained his work.
Robinson is convinced U.S. growers are heading in similar directions as those being forced on European growers, the most important factor being the increasing shortage of orchard workers.
Robinson calculates that it takes 500 hours per acre per year to produce a crop, but he thinks growers can get to 200 hours by reducing the time spent pruning. Additional reductions can come from better chemical thinningreducing the need for hand thinningand use of platforms for pruning, thinning, and harvesting.
Using renewal pruning in tall spindle apples makes pruning easier because it’s simple. It involves removing two or three of the largest branches each winter from each tree and making a few clips to simplify the structure. Some summer pruning is needed to improve light penetration.
But with the hedging system, summer pruning is eliminated, and Robinson thinks dormant pruning can be cut back to every other year or even every third year.
Robinson recalled the early days of his career, when growers were experimenting with mechanical hedging in the 1980s. “Dormant-period hedging on semivigorous rootstocks like M.111 led to an explosion of growth,” he said. “It failed miserably and had to be abandoned.”
In the new system, he said, “We start with a good job of dormant pruning and follow with summer hedging, just a mild haircutting to expose the fruit to light without investing much in labor.”