A tree spur is a stubby side branch that grows off of the main branches of fruit trees. Both flowers and fruit are produced on the spurs. There are several varieties of fruit tree that form spurs. The point in the tree's life cycle that the spurs form varies by type of tree.
Apple and Pear Trees
The fruit spurs on apple and pear trees grow as short twigs with "wrinkled" wood at the base. They generally do not flower or bud in the first year. By the second year, fruit buds develop on the spurs. Fruit will not grow until at least the third year of the spur's life, but once developed, the spurs on apple and pear trees can live more than ten years.
Plums and Nectarines
Spurs on plum and nectarine trees bear fruit somewhat sooner than those on apple and pear trees. Plum and nectarine trees both develop spurs on the new wood of the tree and bear fruit the year following a spur's growth. The fruit buds that appear on plum trees are pointy, while the buds on nectarines are pale and fuzzy. The spurs on plum and nectarine trees will fruit for only three years.
Like apple and pear trees, the spurs on sweet cherry trees will produce fruit for ten years, or more. The spurs that form on sour cherry trees, however, will produce for only three to five years. On both trees, the spurs produce buds that each flower with two to four blossoms. Fruit production occurs on spurs that are only one year old.
Caring for Spurs
Since the spurs of fruit trees are essential to the growth of the fruit, it is essential to recognize them. If spurs are clipped or trimmed, they will turn into longer, non-fruit-bearing stems. Spurs will die if they do not receive enough sunlight or oxygen, so branches on the top and outside of the crown must be thinned enough to allow light through to the spurs on the inside and underside of the tree.
When buds develop on spurs that have reached the fruiting stage, the fruit will not have enough space to grow properly. Pull off extra buds with your fingertips, leaving only a few buds on each spur to develop into fruit.