Jul 1, 2015

Training young apple branches for high density systems

Michigan State University Extension recommends a number of approaches to training young developing apple branches in newly planted, up to 3- to 4-year-old trees in a planting for high density systems. This practice becomes more critical as the trees are planted close together. Young, succulent shoots need to bend down as they begin to develop in the tall spindle and super slender spindle system trees. Training and development can and should begin when shoots are the length of a clothespin (3-4 inches) and up to 10-12 inches in length. Most importantly, remove or suppress (pinch) shoots in the first three to four nodes below the leader as they begin to develop at this time. Shoots can begin to be directed when they are 3-4 inches long by using a clothespin. Clamp the claw to the stem/trunk above the shoot to spread the shoot down (see upper pin in photo).

Longer shoots need bending. Many growers like to use 20 gauge floral wire or UV light resistant training rubber bands. The only challenge with the wire is technicians must return to the trees to remove or move wire to avoid girdling. The advantage of rubber bands is that the bands can be left in the tree without concern for girdling. The third common approach is to use clothespins as weights. Weighting with pins is useful for 8- to 12-inch shoots that bend easily under the weight of the clothespin.

Once the lignin accumulates in the shoot after about 10-14 days, the bending is accomplished and pins as well as wires can be removed or moved to newer developing branches. Some growers have attached multiple pins to more stubborn and less succulent shoots.

— By Ron Perry, Michigan State University Extension, Department of Horticulture