Stefano Musacchi: A top thinker in tree fruit physiology finds a home in Washington state
By Dan Wheat
WENATCHEE, Wash. — He arrived in Wenatchee a year ago, heralded by those who hired him at Washington State University as one of the best thinkers in tree fruit physiology and production in the world.
And Stefano Musacchi hasn’t disappointed as endowed chair of tree fruit physiology and management at the WSU Tree Fruit Research and Extension Center in Wenatchee, says Jay Brunner, center director.
“Dr. Musacchi has lived up to expectations. He has shown that he is the right person for the position in many ways and his leadership will pay many dividends for horticultural science and the Washington tree fruit industry for years to come,” Brunner said.
He praised Musacchi’s knowledge, ideas, attention to detail and skill in collaborating with colleagues at the center and in the industry.
Musacchi, 49, grew up on an orchard in Ferrara, Italy, managed by his father who also managed a tree fruit nursery and bred strawberries. Young Musacchi joined in all the work and enjoyed helping with the breeding.
“If you asked me what I wanted to do in life, when I was a kid, I said, ‘I am doing it now,’” Musacchi said with a smile.
His college years were at the University of Bologna, where he received his master’s degree in agricultural sciences in 1990 and his doctorate in pomology in 1996. He became an assistant professor there in 2000.
His research centered on pomology and physiology of fruit trees and pear breeding. He studied propagation, training systems, rootstocks and cultivars.
He became best known internationally for his innovations of developing the biaxial fruit tree structure for apples and pears and inventing the super slender axe for cherries.
The biaxis for apples and pears involves the removal of the central leader of the tree and development of leaders from two side limbs. It spreads the tree into a single growth plane on trellises to form fruiting walls. This allows maximum light penetration through the leaves of the tree canopy for better fruit growth and color and high, uniform fruit production. Musacchi says it’s easiest for mechanical pruning and thinning and easiest to harvest because fruit is readily seen.
The tree’s energy is divided and vigor is controlled, particularly in fertile soil.
But biaxis shouldn’t be used for all varieties because some, like Granny Smith, need some shade to stay green, he said.
“We have the possibility to cultivate 28 variety of apples and each has a different story,” Musacchi said. “Some are green. Others are red and yellow. There isn’t a unique system to grow them all.”
Part of his work now is determining which system works best for which variety.
There are three main systems for high-density apple and pear orchards. The V-trellis and vertical tall spindle are most common in Central Washington. The biaxis is just being introduced and used by a few growers.
Large old fruit trees of yesteryear are still common but few people plant them now. Compact, high-density trees yield more fruit and are easier to prune and harvest.
The biaxis is common in Italy, where strict limits on pesticide residues and high labor costs have squeezed grower profits and made every aspect of horticulture, including tree canopy design, critical for maximum mechanization, Musacchi said.
The super slender axe for cherries is a single leader tree, a modification of the vertical tall spindle, to control tree growth, reduce bud clusters and produce large cherries on short limbs and the trunk. Low production per tree is compensated for with high-density plantings and production has reached 90 percent at 9.5-row (large) cherries.
Musacchi’s focus at WSU is on apples and pears since Matt Whiting, plant physiologist at the WSU Irrigated Agriculture Research and Extension Center in Prosser, concentrates on cherries.
Among Musacchi’s projects is researching use of a DA meter in pre-storage sorting of pears to determine optimum storage life of fruit. The meter measures the chlorophyll content of fruit, indicating its ripeness.
“Now we pick fruit assuming it’s all the same, but it isn’t true,” he said. “The DA meter allows us to measure the level of ripening so we know how to store the fruit.”
Another project is researching summer and fall pruning of d’Anjou pear to reduce vigorous tree growth. Currently, growers prune in winter. But Musacchi believes that stimulates growth. He’s trying to prove that pruning right after fruit harvest in summer and fall will reduce vigor and allow better light penetration of the canopy to produce more pears lower on trees.
“Right now, 70 percent of the crop is in the outside zone of the canopy. We want to bring more fruit to the bottom, partly because it will be easier to pick,” he said.
He’s also studying using biaxis tree structure in pears to control vigor and have earlier crops.
Fruiting walls are in the future for pears for mechanization but progress has been slowed because there’s no good rootstock available to produce high-density trees, he said.
Kate Evans, WSU tree breeder, Amit Dhingra, WSU genomist, and Todd Einhorn, Oregon State University horticulturist, are working to develop such rootstocks.
Musacchi and others are researching a replacement for Manchurian crab apples as apple pollinators in an effort to reduce disease in apples for export to China. In 2012, China banned U.S. apples for diseases and the industry is trying to regain access.
He’s also working on determining the best management and training system — V-trellis, vertical tall spindle or biaxis — for the new WSU apple variety. Researchers refer to it by its breeding name, WA 38. It will be marketed as Cosmic Crisp.
Musacchi said his job is to understand and improve what is possible in the short term for apples and pears while thinking ahead for the long term.
“Everything that can increase the physiological performance of trees and orchard management,” he said, “that’s what I’m about.”
This article was originally published on July 18, 2014.
Born and raised: Ferrara, Italy.
Family: Wife, Debora Bassi, is an attorney. Daughter, Lucia, 10.
Education: University of Bologna, master’s degree in agricultural sciences, 1990; doctorate in pomology, 1996.
Occupation: Washington State University endowed chair of tree fruit physiology and management.