Strong Leader Growth is Critical When Growing a Weak Apple Cultivar in Years 1 to 3
Posted: June 27, 2012
by Mario Miranda Sazo and Terence L. Robinson, Cornell University
Reprinted from Cornell University Extension's Fruit Notes Newsletter, June 20, 2012, with edits from Tara Baugher
There are several important strategies for maximizing tree growth after planting and during years 2 and 3 including a balanced nutritional program, irrigation, excellent weed control and overall good orchard management.
For those who have planted a weak growing cultivar such as Honeycrisp this year we hope you were able to plant them early, which this year was the end of March. If so, you should by now have 12-14 inches of leader growth. The goal now is to keep the leader growing until the end of July through intensive water and nitrogen management and achieve 18-24” of shoot growth. To achieve this we assume that (1) you quickly installed the new trellis and irrigation lines after planting, (2) you selected the leader when 2” long and removed buds #2-4 when 1” long, (if this was not done you should now cut competing shoots back with clippers to 2” long) to prevent competition with the leader, (3) the new trees have grown healthy, without weed competition, mildew, and fire blight, (4) water (when needed) has been supplied by trickle irrigation with low doses per tree but frequently, (5) flowers were manually removed and (6) about 2 weeks after planting the trees received a small dose of nitrogen (1/4 lb. of calcium nitrate) carefully applied in a doughnut shaped band around each tree.
Before the end of June, apply a second application of ¼ lb. of calcium nitrate around each tree and manage irrigation more intensively. Water should be applied 2-3 times per week (unless we get more than 1” of rainfall that week) but with relatively small volumes each time (2-3 gallons per tree). These applications encourage maximum and safe leader growth. It is also imperative to maintain excellent insect control and excellent weed control at least through the end of July. This should result in 18” of leader growth by the end of the year.
If your trellis has not yet been installed make sure to install a 10 foot tall trellis using 12 foot posts with inline spacing no more than 35 feet so trees are properly supported to the 10 feet height. The trellis should have 3 wires if there is a vertical supporting element such as a conduit pipe, a bamboo, or a wire stabilizer. It should have 4 wires if no vertical supporting element is used. The leader should be attached to the trellis with a rubber band or a wire loop as soon as it reaches each successive wire. With young trees that have crop, the unsupported terminal portion of the leader above the last wire should be de-fruited for maximum shoot growth and good lignification during years 2, 3 and 4. Interestingly, the twisting of the leader to a vertical wire stabilizer works, supports the leader, and encourages new growth above where it is supported by a tie at the trellis wire. A good, strong, and tall support system for a high density orchard must be viewed as an investment (rather than just an orchard establishment cost!) that allows fruit production in the early years while preserving the vertical tree structure (without ever bending the top if unsupported!) and canopy for future large, mature yields from the bottom to the top of the tree.