Tuesday, July 10, 2007

Limb Spreading on Apple Trees

Depending on the apple variety, many apple trees will have a very upright growth habit. This tree shows the typical growth pattern. The problem with upright growth is that the limbs form a narrow, weak attachment to the trunk. Limbs with narrow angles can easily break under the weight of a fruit load. Also, the upright growth forms a dense tree canopy which prevents sunlight penetration and reduces air movement in the tree. In addition, limbs need to be spread in order to get fruiting wood established along the entire length of the limb instead of just at the tip.

To improve limb angles the individual limbs must be spread manually. Spreading is best done when the twigs are relatively new. The object is to get the limb angle going into the trunk as close to 90 degrees as possible. The top limb on the left shows the proper limb angle.

Limbs can be spread using a variety of techniques. For new growth that is less then 6 inches long, a toothpick can be inserted between the limb and trunk to get the proper angle. For larger limbs, tree spreaders can be used just like the toothpicks. In the top photo you can see a commercially produced limb spreader being used. Anything can be used to spread the limbs as long as it is strong enough to hold the limb open. In the bottom photo, a string is used to tie down the limb. Make sure if you use string, do not to tie it too tightly to the limb as this will girdle the limb as it grows.

Spreaders do not have to be in the tree permanently. In fact, after about 4 to 6 weeks the spreaders can be removed and the limb should stay at the proper angle. Spreading is a continuous process that must be done every year to insure proper tree structure.

No comments: