CORVALLIS, Ore. —High-density, "flat" pear orchards may gradually replace the conventional-looking 3-D variety if growers adopt a new system expected to help Oregon growers keep ahead of international competition by countering rising labor, land and fuel costs.
OSU Extension faculty are growing shorter trees – eight to 11 feet tall, compared to the usual 16-footers – that are three times closer together than in normal orchards and against wire frames. Challenging the image of how a pear orchard should look, the trees grow "flat" and can easily be cared for without ladders.
When pruning, thinning and harvesting, laborers ride between rows on a semi-autonomous mechanical platform that is self-steering.
"We've built economic parameters to compete in the global economy," said Clark Seavert, OSU Extension agricultural economist. "This is the first time in the Oregon pear industry that a project is driven by economics."
OSU Extension Service faculty at the Mid-Columbia Agricultural Research and Extension Center in Hood River were instrumental in developing the process, called the Competitive Orchard System (COS). The concept evolved from a project that measured economic impacts of implementing new technologies, Seavert said, and how the minimum wage rate would affect the tree fruit industry. "It was evident that financial paradigms were going to change quickly."
"A COS is about evaluation and management of established orchard blocks and establishing new blocks to be efficient and profitable," he said. Growers make at least a 15-percent return on their investment by growing 90 percent of the fruit as target fruit, which generates a profit over and above the production, harvest, packing and marketing costs.
For pears, the greatest savings are in labor efficiency. Researchers are growing several varieties of dwarf pear rootstocks at the Hood River Experiment Station to find alternatives to conventional orchards.
"Opportunities to grow a smaller pear tree that begins producing fruit in the third or fourth year have been thwarted by a lack of dwarfing, precocious rootstocks," said Janet Turner, horticultural research technician and manager of the pear rootstock trials. "Therefore, we are testing rootstock from around the world, as well as domestic clones, to find characteristics to create a more efficient orchard system," she said.
Another advantage to finding a dwarfing rootstock is production of a marketable crop by the third or fourth year. The normal start for harvesting a crop of Anjous is the fifth year.
European growers transitioned to a high-density system about 15 years ago, Turner explained, from standard plantings of less than 300 trees an acre to systems that can handle up to 1,000 trees an acre.
Dwarfed apple and cherry trees are already growing at high-density in the Pacific Northwest. Pears are the focus at the Experiment Station because 40 percent of the nation's pears are grown in the mid-Columbia River region.
Many Oregon growers are experimenting on their own as part of a joint effort. "They are moving with us," Seavert said. "We don't have time to wait."
In the trials, one of the main challenges is managing vigor of the trees, Turner pointed out. "New shoots must be removed because proper light in the canopy is crucial to success of high-density plantings," she said. "Trees also must be managed to fill only the space allotted to them, without encroaching upon their neighbor."
Final results are not available yet. "Give us another three years, and I think we'll know if the trees can be productive," Seavert said. "In the meantime, we will get information and new tree stocks out to growers as soon as possible."
"Our goals are very rigorous," Seavert said. "The trees must develop a mature fruiting canopy by the third leaf, yet be manageable with adequate light penetration to make the system a successful alternative to the sprawling, labor intensive systems that exist today."