—by Ross Courtney
California stone fruit growers want what apple growers have — new varieties in high-density plantings with uniform fruiting walls that offer efficiency for both human hands and mechanical tools.
“Everybody is bringing the trees closer together and getting more yield, but it costs more to start,” said Johnny Diepersloot, owner of Elkhorn Farms of Kingsburg.
The International Fruit Tree Association, more attuned to apples, toured Central California’s fresh stone fruit orchards in July. The group visited four growers near Fresno, where the bulk of the nation’s stone fruit is grown, as well as university peach rootstock trials and a breeder.
Diepersloot showed the IFTA crowd a block of Majestic Pearl white-fleshed nectarines and a block of pluots on quad V training systems.
The quad V — four leaders angled into a vase shape — was a common sight on the tour, but Diepersloot said there is no standard in the Central Valley. Everyone is trying different approaches to yield, labor and water efficiencies. In his experience, a 60-degree V offers the best balance of light interception and structural stability.
Thinning is one of his biggest expenses. He has spent $2,500 per acre to thin stone fruit this year. His pluots set so heavy he used prop wood to augment trellis wires.
HMC Farms, also in Kingsburg, has not planted a traditional block with freestanding trees since 2018, said Drew Ketelsen, production manager. They plant high-density whenever a block ages out and also on new ground.
Ketelsen showed the tour group Honey Punch pluots with red fruit well-spaced at the exterior of a thin canopy. The orchard was spaced 13 feet by 6 feet with two leaders trained in-row on the same vertical plane. He also showed a late nectarine called September Bright with eight rows under drape netting for rain and hail protection, a tool he began experimenting with just this summer.
The systems and techniques are constantly a work in progress, he said, dependent on variety, soil and year. Sometimes they have one leader, sometimes two, sometimes four cordons trained horizontally. Sometimes crews aim for formal, detailed training; other times they experiment with a light touch.
“It’s something we’re always working on,” he said. “It’s what makes this fun.”
Planar systems allow mechanization. Growers on the tour discussed hedging, topping, string thinning and using platforms — a common sight during the tour.
If they have platforms, most growers use the Alpha 1, a green, self-driver made by S&S Metal Fabrication of Kingsburg. (Diepersloot builds his own tow-behind platforms.)
Each unit retails for $84,000. In five years, the company has sold about 140, almost all of them within 50 miles of their plant, said Blake Dodd, one of the owners.
Rootstocks and systems
Nemaguard is the most common rootstock for fresh peaches and nectarines in California, and Citation is most common for apricots and Japanese plums.However, the industry has vigor-regulating options as well.
In 2013, the University of California released the Controller series of peach rootstocks. Controller 6 has about 60 percent of the vigor of Nemaguard, while Controller 9 has 90 percent.
At the University of California’s Kearney Agricultural Research and Extension Center, retired extension specialist Kevin Day showed IFTA a trial of Controller 6 and Controller 9 rootstocks with peach varieties June Flame and August Flame. The block included two-leader trees planted at 15- by 4-foot spacing and quad Vs at 15 feet by 8 feet. Trees were topped at 8 feet.
The systems all worked, Day said, because they allowed evenly distributed sunlight throughout the top and bottom of the tree.
“All of the dwarfing rootstocks have performed as good as, if not better than, Nemaguard in terms of yield and (fruit) size,” he said.
Day estimated California has between 500 and 800 acres of Controller rootstocks in commercial production. Nurseries are still gauging the series’ value and working out the kinks with growing them, he said. They all root easily but differ in vigor, nutritional needs and onset of dormancy, he said.
Consolidation and innovation
As in Washington’s apple, pear and cherry industries, the stone fruit industry of Central California is under consolidation, with larger companies controlling a larger share each year.
To survive, Warmerdam Packing of Hanford, a longtime peach and nectarine grower, branched out. “We did it by diversifying and focusing on crops that gave us a niche or an advantage,” said John Warmerdam.
About 12 years ago, the family planted Sweet Pixie, an interspecific cross between a cherry and a plum, branded as Verry Cherry Plum.
Outside marketers turned up their noses at what looked like just a small plum, but Warmerdam sold the fruit through The Flavor Tree Fruit Co., the sales desk of which his family is a partner. The company produces about 500,000 25-pound box equivalents. They sometimes retail for more per-pound than Washington cherries, he said.
“It almost takes on a life of its own,” he said. “We have this cult following of people.”
Sweet Pixie yields 9 tons of packed fruit per acre, compared to about 5 tons for cherries. Packing costs are lower, too, with larger fruit size and fewer defects.
The company started by training the precocious variety on a quad V at 6- by 14-foot spacing but struggled with suckers and sunburn on the middle branches. New plantings are spaced 5 feet by 9 feet with two parallel leaders.
New varieties
Many interspecific fruits — crosses between species, such as the pluot with its plum and apricot parents — come from Zaiger Genetics of Modesto. Leith Gardner, a second-generation breeder, led the tour group through her fruit and nut cultivars. They sampled one unnamed, experimental apricot right off the tree.
She also has some rootstock trials.
Almost all of her varieties are open but sold through an exclusive partnership with nearby Dave Wilson Nursery. Warmerdam’s Sweet Pixie is an exception; the family has exclusive rights.
With her daughter and nieces helping, Gardner plants about 70,000 seedlings each year. Of those, maybe 700 make it to what they consider the second stage of testing, and then only one or two end up with a patent. She has bred fruit named for California beaches, growers’ family members or streets in hometowns.
“I get sentimental about some of them,” Gardner said. •
Leave A Comment