Organic Methods to Promote Branching in Nursery Apple

View the project final report

Commodities

• Fruits: apples

Practices

• Crop Production: nurseries
• Education and Training: on-farm/ranch research
• Production Systems: organic agriculture

Most commercial apple growers now raise closely-planted orchards of dwarf trees grown on trellises because these orchards are more profitable. In these orchards it is economically critical to plant highly branched (feathered) trees, which bear fruit more quickly and provide a faster return on investment. However, the only sources of feathered planting stock are commercial nurseries which raise non-organic apple trees with intensive pesticide use and spray synthetic growth hormones to promote branching. Although organic standards permit planting non-organic trees, we and many other organic growers in our region prefer to graft and raise our own trees organically to produce trees in a more ecologically sound way and to grow uncommon varieties which are well-suited to our orchards and markets but which are not available through commercial nurseries. We are able to raise healthy trees in our on-farm nursery using organic methods, but we have not produced well-feathered trees.

In this project I evaluated two methods to promote branching in our organically managed on-farm nursery: manual leaf removal and sprays of a seaweed extract high in cytokinins.  Manually removing young leaves near the growing point of the tree increased branching slightly, and spraying trees with a seaweed extract high in cytokinins reduced branching slightly. In addition, taller trees had more branches, there were strong differences between varieties in branching, and individual trees varied greatly in both height and branching. The cost in materials and labor for raising a tree in this system was approximately $11.95-$12.08, excluding overhead costs and costs of facilities and equipment; the different treatments to promote branching had minor effects on the overall cost of raising a tree.

I shared results with other organic apple growers through a report on our website, an on-farm field day, emails to two grower list-serves, articles in two fruit growing publications, and a poster presented at the 2019 Organic Farming Conference in La Crosse, WI.  Other growers participating in the outreach events expressed their frustration at being unable to produce feathered trees and their interest in the organic methods I trialed in this study.

1. In an on-farm nursery of grafted apple trees, compare manual leaf removal and organic cytokinin sprays to an untreated control. For each treatment, record data on material cost and time required, tree growth, and feathering.
2. Share results with other organic apple growers through a website, an on-farm field day, emails to grower list-serves, articles in fruit growing publications, and a conference poster