Choosing an orchard system and density
A standardized orchard system can take the art out of horticultural tasks, making labor more efficient.
An example of a highly organized V trellis system used by Washington’s Auvil Fruit Company
With the site, rootstock and variety selected, the next major decisions involve the type of orchard system and density.
To be competitive in today's global apple market, orchard systems must provide early returns, produce uniform fruit with good size, and be labor efficient.
Upright or vertical systems have more options and flexibility when it comes to tree shapes that will meet the needs of the future. The upright system is easier to change down the road than a V or angle system if machines come along that haven't yet been considered. A vertical, high-density system is used in almost all orchards at McDougall and Sons, Wenatchee, Washington. By using a standardized system in all blocks, orchards are more uniform from block to block and more like a factory setting, explains Scott McDougall. Vertical systems are also fairly easy systems in terms of pruning, and at high density, can hold production levels with constant wood renewal, he said.
"Our system was designed to take advantage of a female work force to do picking, pruning, tying, clipping, and suchall on platforms," he said, adding that much of the world is using cylinder tree shapes.
Double Diamond Fruit General Manager Mike Robinson, who previously worked for Auvil Fruit Company in Vantage, has firsthand experience with angled tree systems. Auvil Fruit, known for its high production and tree uniformity under the angle system, has been a stop for many orchard field days and tours.
The V or angle system is designed for fruit to hang down under the V, making harvest easy, Robinson said. But fruit doesn't always hang where you'd like, and the best fruit that needs the most thinning tends to be on the back side (inside of the V). If chemical thinners are used, they must be blasted upward underneath the angle to reach the back side. Fruit hanging on the back side is also more susceptible to sunburn, he said.
"I learned that 'espalda' is Spanish for back," he said. "I spent all of my time at Vantage telling the crew to 'look at the back side of the tree.'"
Benefits with V systems are that platforms and future technology can work very well, depending on the angle, he said. "The tall V angle at Vantage worked perfect with platforms. If you mechanically thin, then the V makes sense, but not if you are chemically thinning."
Robinson recently planted apricots to a V system and plans to use a mechanical string thinner for blossom thinning and to pick fruit from platforms.
For Robinson, high-density orchards equate to high risk. But for others, high density is a way to bring orchards into production quickly.
An economic study of different densities and planting systems by Cornell University's Dr. Terence Robinson found that the greatest profitability for eastern U.S. growers resulted in a density range of 900 to 1,200 trees per acre, unless fruit prices were very high. Although higher density systems generate higher early returns and higher cumulative yields, he found there is a law of diminishing returns when it comes to tree density.
With higher densities, matching the rootstock and scion is very important because more dollars are at stake. "Little mistakes become magnified if anything goes wrong," Robinson said, adding that he's seen high-density plantings succumb to winter injury, turning the block into a "gap-toothed grin."
"Now it's a hair puller. You've spent $25,000 to $30,000 per acre, and you're trying to get efficiencies from an orchard with gaping holes."
Robinson believes that the early production rewards from high density even out when trees are mature, leveling out to yields equivalent with medium-density orchards. Also, years that give the most inconsistent fruit quality are the early years, he said, adding that high density requires a big investment of money and skills when the fruit itself is risky. "You get the crappiest fruit from the early years, and you've just taken on the biggest investment for fruit that will most likely not pack well."
McDougall and Sons uses high density for almost all of their orchards and varieties. Vigor is adjusted by the choice of rootstock, according to McDougall. Trees are spaced at three feet between trees, and ten feet between rows, which equals about 1,450 trees to the acre.
He's found that a wider spacing5 feet by 14 feetrequires a lower scaffold that takes away energy from the top of the tree. He thinks that row widths of even 12 feet are too wide, resulting in empty space and tempting growers to let bigger limbs encroach the drive roads. The closer spacing forces them to get the bigger wood out, continually having younger wood to produce the best and strongest fruit. And, the system is easy to prune, he added.
Limbs are tied with kite string to point the tips downward, unless the feather is weak or soft. At planting, anything on the tree that is half as big or larger than the main trunk is pruned to avoid bigger branches. McDougall uses the plant growth hormone Apogee (prohexadione calcium) to help eliminate some summer sucker pruning and control tree growth on such tight spacing. Usually four applications of Apogee are made during the season, with the first application at pink stage.
"The cost of tying is expensive, but we can get high early production that would otherwise be vegetative. We've never gotten to the point where we can afford not to capture that wood," McDougall said. "Otherwise, we'd be cutting out wood in the winter. With tying, we've more than gotten the payback."
Robinson prefers a medium tree density, around 600 to 1,000 trees per acre (mostly 4 by 12 feet , but some 5 by 12 feet) in his plantings. He thinks 14-foot rows are too wide and result in wasted space, but 10-foot alleys require lots of chopping to keep the tree within the space. "Yes, you can get the tree in that width, but you'll make the tree mad."
With bins 4 feet wide, 12-foot alley rows give enough room for the limbs to grow out naturallywithout heavy pruningand still provide enough room for mechanical equipment of today and the future, he said.