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OSU Researcher Driving Blueberries up a Tree

Try to imagine blueberries growing on a tree and not a bush. Now consider that your mind may not be playing tricks on you.

Oregon State University blueberry extension agent Wei Yang, Ph.D., who works out of the university’s North Willamette Research and Extension Center near Aurora, has just begun to experiment with tree-borne blueberries.

Last year, financed with federal Specialty Crops Research Initiative grant monies and matching funds from the Oregon Blueberry Commission, Yang grafted three highbush blueberry varieties – Duke, Bluecrop and Elliot – onto wild blueberry tree rootstocks that originated in both eastern Texas and Oklahoma.

Now why would anybody want to do that?

One reason, says Yang, is to eliminate fruit loss during machine harvest. “With the bush form, during harvest you have lots of berries falling to the ground. With the tree type, you have fewer berries falling to the ground because the catch plate from the mechanical harvester will be able to close very tightly around the trunk.”

It’s somewhat similar to machine harvesting cherries, Yang said.

He added that blueberry trees have been known to yield up to 30 pounds of fruit per tree, compared to 15 pounds when grown on a bush.

While overall yields may not increase that much due to the wider spacing that blueberry trees will need, growing blueberries on trees could very well offer several advantages over growing berries on bushes, Yang said.

One would be better drought tolerance. Others include higher resistance to certain diseases and the elimination of the need for organic soil amendments, such as sawdust. Yet another feature could be increased cold tolerance.

Yang, who is in the second year of a five-year project, has been both budding and whip grafting blueberry scion wood in the greenhouse onto the tree rootstock. Next year there should be a “large block” of trees at the research station.

He said that while some people have tinkered with growing blueberries on grafted rootstock, this is the first time worldwide that a major study has focused on doing that on a commercial scale.

“The goal of the project is to demonstrate in a commercial planting if blueberry trees will work. I can give you a blueberry tree right now and it will grow in your back yard. We want to know if the trees will grow (the desired cultivars) on a large scale.”

Yang said blueberry trees, which should start bearing fruit about the same time as bushes, can reach heights of up to 14 feet, “but you may not want them that large for commercial production.”

He added that while he plans on giving the tree-borne blueberry project a lot of attention, growers should not get their hopes “too sky high.”

Oregon Blueberry Commission • P.O. Box 3366 • Salem, Oregon 97302
Paid for by the Oregon Blueberry Commission, an agency of the State of Oregon.