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Pear Pruning and Horticulture in Higher Density Systems Demonstration

On February 5, 2018 Stefano Musacchi, WSU Endowed Chair of Horticulture and Bob Gix, Blue Star Growers discussed pruning horticulture with fifty-four growers at a WSU Extension Field Day in Yakima, WA. The discussion focused on Bartlett in higher density systems. The goal was to discuss horticultural possibilities, options and creative solutions. Then growers can decide what is practical and how to implement.

Here we will summarize three main discussions from the field day: minimizing shade, angle for V trellis pears, and renovating fruiting wood. Join us February 19 for another pear field day in Cashmere.

Trees with a lot of areas like this (left) which do not have flower buds need renovation to increase production.
The goal is fruiting wood like this (right) with healthy buds.

Minimizing shade: When our goal is fruit, minimizing shade is important. Buds will only differentiate to form flower buds if there is more than 30% of the ambient light. “Light is the only thing we don’t pay for,” Musacchi reminded us, “How you use the light is critical.” Taking out large branches that produce too much shade can help manage this challenge. The angle of the canopy will also designate the shadiness in a V system.

Angle in V trellised Pears: Pears have strong apical dominance. If we grow them at too flat of an angle the trees will become ‘angry’ and produce many suckers. Leaders with many suckers can become exhausted and have few flower buds. Also canopies with too flat of an angle will reduce the light, sometimes to the point where there are only a few hours per day with adequate light. The result will be a concentration of the flower buds at the top of the tree with little fruiting wood down lower. “If we have too flat of an angle the trees behave like old trees,” Musacchi explained. Pears on V trellis should be planted with an angle of only 10˚ from vertical.

Pears trained to a V should be at about a 10 degree angle (just slightly off from vertical). Flatter angles like this promote suckering on the sunny side of the tree and too much shade on the shady side.
Stefano Musacchi, WSU Horticulture at pear pruning demonstration in Yakima, WA.

Renovating for fruiting wood: In this situation where there is an area lower in the canopy with insufficient fruiting wood and flower buds, Musacchi suggests a three-year cycle pruning strategy: year 1) remove bigger suckers, prepare new fruiting branches by bending and tipping, prune this year’s fruiting wood, one big branch in the top can be removed, and reduce the height on one side of the angle canopy; year 2) continuing to remove suckers, prepare new fruiting branches, one old branch in the top of tree can be removed and reduce the height of the other side of angle canopy; year 3) start to rotate old branches and prune the one removed with a stub to produce new shoots. “It takes 3-4 years to transition from one style to another,” Musacchi explained.

Musacchi removing a large sucker.

Year 1

 

 

Bob Gix, Blue Star Growers tying a one-year-old branch to a 45 angle to create new fruiting wood.
Stefano Musacchi, WSU Horticulture making a heading cut on the tip of one-year old wood, ‘click’ in order to break apical dominance and get the branch to make new shoots.

Year 2-3

Year 3-4

Join us February 19 for the next pruning and horticulture discussion in Cashmere WA. http://treefruit.wsu.edu/event/pear-pruning-demo-northern-site/

Contact

Tianna DuPont

Tree Fruit Extension Specialist

tianna.dupont@wsu.edu

(509) 663-8181