Apple trees produce fruit in one of two ways, on the tip or on the spur. Tip-bearing trees produce apples on the end of the previous year's branches. Spur-bearing apple trees produce fruit on small spur or thorn-shaped branches extending off the main tree branches. This difference in apple trees affects both the mature tree size and production of fruit.
Spur-Bearing Apple Strains
Growers select mutations of certain apple cultivars that show improved characteristics as selected strains, according to the Clemson Cooperative Extension Home and Garden Information Center. The grower propagates the strain by grafting the new strain to a combination of different rootstock in order to develop a highly desired variety of apple trees. Over 1,000 different varieties of spur-bearing apple varieties have been cultivated from tip-bearing trees. This results in the same type of apple, such as Red Delicious, being available in both spur-bearing and tip-bearing varieties.
Benefits of Spur-Bearing Apple Varieties
Spur-bearing apple trees feature an upright growth pattern of stiff branches, reducing limb breakage from heavy crop loads. Home growers often find that spur-bearing apples rarely require limbs to be propped or tied due to their compact growth. Spur-bearing apples are naturally dwarfing trees, up to 70 per cent the size of their tip-bearing counterparts. Due to the smaller tree size, fruit is produced earlier.
Pruning of Spur-Bearing Varieties
Tip-bearing varieties bear fruit on the new branches form the previous growing season. The removal of these branches will decrease the production of apples. Growers need not worry about removing these branches on spur-bearing varieties, which produce spurs on two-year old shoots off the main branches. Special attention should be paid to older spur-bearing trees as the spurs easily dominate the tree, slowing the annual shoot growth. The removal of old spurs is essential to encouraging new spur growth.
Identification of Spur-Bearing Varieties
The best time to determine whether a tree is tip-bearing or spur-bearing is while the tree is in bloom or fruit. Flowers or apples on the tips of branches indicate a tip-bearing variety. Flowers or apples growing from 4 to 10 inch spurs attached to thick stubs on main branches indicate a spur-bearing variety. If the tree has both types of fruit growth, it is a semi-spur variety that combines the features of both trees.
Examples of Spur-bearing Varieties
Spur bearing varieties include Breakey, Rome Beauty, Acme, Ace Spur Delicious, Arkansas Black, Annie Elizabeth, Hawkeye Delicious, Shamrock, Goldspur, Red Delicious Spur, Cascade Spur, Winesap Spur and Spur McIntosh. The University of California Cooperative Extension recommends that spur varieties be rooted on seedling rootstock instead of dwarf rootstock for optimum performance.