Issue link: http://read.dmtmag.com/i/560612
Dynamic keeps trees productive With constant renewal of limbs, pear trees will continue to produce large, high-quality fruit. by Geraldine Warner I talian horticulturist Dr. Stefano Musacchi is introducing his concept of "dynamic pruning" to Bartlett pear growers in Washington's Wenatchee Valley. Dynamic pruning involves rotating branches to minimize the aging of the bearing wood and maintain production of high fruit quality. Branches are pruned on a three-year cycle so that new branches are constantly being produced in the tree. In year one, a branch is removed, leaving a stub. In year two, a replace- ment branch grows from the stub. In year three, spurs on the new branch will produce fruit. Branches need to be maintained in their space and not overlap. Some growers never remove branches unless they are too big, Musacchi said, but unpruned branches tend to become old and not very productive. "If you don't have other branches ready to replace them, we'll be in trouble," said Musacchi, who is now a research pomologist with Washington State University in Wenatchee. "Fruit quality will decrease in the future for sure. We have to make some renewal and try to correct the branches that are too drooping. The idea of dynamic pruning is nicer because you are always trying to renovate the wood." A spindle tree has a conical shape, with strong basal branches and smaller, weaker branches in the tops. Branches can be bent to flatten the branch angle and promote fruiting, as is commonly done on apples, but a pear tree's with all the suckers at the top. In addition, it should improve harvest efficiency. "Can you imagine if we can harvest with a platform?" Musacchi asked. "A dream for me is when we'll be able to harvest 70 percent or more fruit from the ground. Now, we have 80 percent in the top of the trees. "I'm really thinking that this orchard is for me a key orchard because it can provide a lot of information." • "If you spread the vigor on 44 branches instead of 22, you have a dramatic reduction of the growth. It's a simple idea, but it works." —Stefano Musacchi This high-density Bartlett pear orchard, which incorporates a bi-axis system, could be a model for new plantings in Washington. PHOTOS BY GERALDINE WARNER/GOOD FRUIT GROWER PRUNING Mechanical pruning can have the same effect as detailed pruning by hand, though the cuts are not selective. Buds develop in previously blind wood. www.goodfruit.com GOOD FRUIT GROWER SEPTEMBER 2015 21