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Pears will have to be grown in high-density systems in the future in order to produce high yields of target fruit, a group of pear growers said during the Washington State Horticultural Association’s annual convention.

"Going to these higher density systems is going to be absolutely crucial," said Don Weippert of Sunnyside, Washington.

Weippert has Bartlett pears planted on a 4- by 12-foot spacing. The trees are on Old Home x Farmingdale 97 rootstocks and are supported by a three-wire V trellis at 75 degrees from horizontal. The trees have three vertical leaders tied to the wires. The top wire is at 11 feet. Weippert believes it’s important to have a fairly upright trellis angle for pears, because it allows for more trees per acre and generates less suckering between the trees. Planting at high densities means growers don’t have to worry about developing the structure of the tree, but the costs of planting the orchard are high.

Weippert estimates that the cost to develop the orchard to the third leaf, when it begins to produce, is $13,500 per acre, assuming a land cost of $4,000. He said he would like to try planting pears as bench grafts or sleeping eyes, to reduce establishment costs.

The goal is to harvest 5 bins per acre in the third leaf, 30 bins in the fourth leaf, and 30 to 35 bins per acre of fresh quality pears by the fifth leaf. He aims to have most, if not all, the pears large enough for the fresh market. He feels it’s important to have good pollination and plants 56 pollinizers per acre.

To avoid profuse suckering in the trees, he doesn’t bend the top of the leader until he really has to and does not head it. His goal is to create a flat fruiting plane so that workers can reach the entire canopy from the ground or a platform. This system lends itself to sorting at harvest time, he said.

Steve Hull of Firewood Orchards, Yakima, Washington, has pear trees planted on a 4- by 13-foot spacing on a Tatura trellis, on OHxF 97 rootstocks. Young Bartlett trees grow well on a drip irrigation system, but they bear better with an undertree irrigation system.

Hull said large pears grow in the tops and outsides of the trees, and the Tatura trellis system allows better light distribution throughout the tree, though the lower part is still where the smallest pears and blank wood are. He prunes the trees hard. Ripping suckers off reduces the cost of dormant pruning, though care must be taken to prevent the wounds becoming infected with fireblight.

If there is too much blank wood in the lower limbs, he trains a sucker down and removes the limb.

The orchard has been productive, yielding up to 40 bins per acre. "With all the pears on one plane, it’s easy to thin the fruit and take off the junk," he said.

Pickers use a three-inch ring to pick for size and are able to harvest most of the crop from the ground.

Comparison

Randy Smith, a pear grower in Cashmere, Washington, has a tenth-leaf high-density pear block that was planted as a deficit irrigation and rootstock trial by the Washington Tree Fruit Research Commission. It has three varieties-d’Anjou, Bartlett, and Bosc-on four rootstocks: OHxF 40, 69, 87, and 97. Bosc and Bartlett are on a 6- by 14-foot spacing and d’Anjou on an 8- by 14-foot spacing.

Smith said he’s realized that a grower shifting to high-density production needs to have a completely different mindset than a traditional pear grower. The trees are trained to a slender spindle system where the only permanent limb is the center.

The block was planted in 1996. When it was in its fourth leaf and about to produce, a frost wiped out the whole crop, but the following year, he harvested almost 100 bins from the 3.7-acre block. Since then, it has produced between 132 and 170 bins a year.

Another block that he leases, which is the same size and was replanted a year later, has Bartlett, Bosc, and d’Anjou trees on a 10- by 20-foot spacing, and Concorde on an 8- by 20-foot spacing. That block produced 218 fewer bins than his own block during the last three years combined. Using a conservative figure of $200 per bin return, that’s a difference of $43,600, or almost $12,000 per acre, over the three-year period.

"How can we afford not to go high density?" Smith asked.