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WSU Extension educator Tim Smith discusses a demonstration planting of d'Anjou pears

WSU Extension educator Tim Smith discusses a demonstration planting of d’Anjou pears

Pear growers who plan to be in the industry a while longer will need to consider alternatives to the standard way of growing pears, says Tim Smith, Washington State University Extension educator.

Old pear trees don’t yield enough, are difficult to prune, and make pest control challenging because of poor spray coverage. When the labor supply is tight, pickers will be able to choose between climbing ladders to pick pears from tall trees that are sticky from pear psylla or picking apples from a platform in a –modern Gala apple orchard.

Even though they might never use platforms in their orchard, as the apple industry is doing, pear growers will have to grow target fruit and more of it to stay in business. Smith said the average yield in Washington State pear orchards of 35 bins per acre is not enough.

In August, Smith conducted a tour of a demonstration plot of d’Anjou pear trees on Old Home by Farmingdale 87 rootstocks planted six feet apart on a ten-foot high, four-wire trellis. The planting is in its second leaf. Smith expects the trees to fill the trellis by next year and start to produce some fruit. The objective is to reach full production of 50 bins per acre in the fifth leaf and have the planting paid for by the seventh leaf or sooner. The cost of planting the trees and installing the trellis was $7,000 per acre.

As well as experimenting horticulturally, Smith said he’s looking at the –economic feasibility, since pears don’t generate the same high returns as managed apple –varieties such as Jazz.

Smith said OHxF is a vigorous rootstock for a trellised system, but it was the best available option. Limbs are spread on the wires to encourage fruiting. Smith said he doesn’t like to pull limbs totally flat because it stimulates sucker growth, but if limbs are too upright they grow too vigorously. Vigorous branches will be removed and the wood renewed. He controlled the height of the trees by pinching the leaders. "This is critical to slow down growth of the top of the trees and get weaker branches," he explained.

"The whole idea behind the wire is to support limbs without them going pendant," he said. "If they’re –pendant, you get small fruit."

He might use the growth regulator Apogee (prohexadione-calcium) to restrain vigorous growth and keep the trees within their space.

The planting has Bartlett trees as pollinizers, and Bartletts do well on wire because the variety fruits easily, Smith said. "But d’Anjou is the true test, because it’s reluctant to fruit."

Rootstock trial

Smith is also conducting a rootstock trial at the Cashmere orchard, which also has d’Anjou as the main variety and Bartlett as pollinizers. Bartlett trees on Horner 4 have a significant amount of fruit in the third leaf. D’Anjou trees on Horner 4 have some fruit on them and should have a crop next year. Smith said Horner 4 gives a vigorous, but productive tree.

The oldest trees in the rootstock trial were planted in 2002 as freestanding trees and allowed to grow naturally so their growth habit could be evaluated. Smith said that in his experience the Pyrodwarf rootstock is productive, but the fruit is inherently smaller than on trees on other rootstocks. Pyro 2-33 has a better balance of fruiting and growth, but produces strong, thorny root suckers. If Pyro 2-33 proves to be a superior rootstock in other respects, growers will be able to manage the suckering, Smith said, though they will need to "prune" the ground regularly to prevent the suckers becoming too big and thorny, and that would mean added labor. In the trial, Pyro 2-33 has consistently produced a larger tree than OHxF.87.

So far, no pear rootstock has been discovered that can do for the pear industry what Malling 9 has done for the apple industry, Smith said. He noted that promising selections from a planting of Horner rootstocks in Hood River, Oregon, will be put on the fast track and planted in commercial orchards for large-scale testing, but it still could take another 15 years before a winner becomes commercially available.