—by Ross Courtney
The sprawling flatland of California’s southern Central Valley dominates U.S. stone fruit production. And the International Fruit Tree Association tour group saw plenty of it on the final day of the summer study tour through Central California, held July 16–18.
Braving three-digit highs, the sunscreen-lathered group hit four of the nation’s largest stone fruit producers and the University of California’s Kearney Agricultural Research and Extension Center.
At all stops, speakers discussed efforts to convert from the large, spacious trees of tradition to the high-density, planar systems that make workers — and any tools they might use — more efficient.
Many growers at least train young trees on trellis wires, while others use them formally for the life of the orchard, as apple growers do. Platforms, mechanical thinners and hedgers are common tools. Two robotic harvester companies — mostly designing for Washington’s apple orchards — run trials on Fresno-area stone fruit early in the season.
A few growers use nets, but not always for shade.
Warmerdam Orchards erected angled netting to help their plums cycle through dormancy each year, meaning they deploy the nets in the winter, said John Warmerdam. The black, specialty fabric limits the trees’ exposure to light wavelengths that could signal the trees to wake up from dormancy too early.
Just this summer, nearby HMC Farms put up single-row unstructured netting to protect peaches from hail and rain, said Drew Ketelsen, part of the family that owns the orchard. When a heat wave arrived earlier in July, crews pulled up the sides of a few rows just to experiment with how netting will change the trees’ reaction to the high temperatures.
At the UC Kearney field station, retired extension specialist Kevin Day showed the tour group trials of training systems on the Controller series of rootstocks, one of a few vigor-controlling options to replace the industry standard Nemaguard. •
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