Knowing the cropping habit of your apple trees and indentifying which buds produce leaves and buds will enable you to prune for the optimum harvest and at just the right time. If you know which cultivars are tip-bearers or spur-bearers, you can choose and train apples to whatever form you have in mind.
When to identify fruit buds
Fruit buds can be identified from mid-summer, but are particulary apparent after mid-autumn.
Identifying apple buds
Apple trees produce two types of buds:
- Fruit buds, from which the flowers, and then fruit will form
- Wood or growth buds, carry leaves, but no flowers
By identifying which buds are which, you can ensure that you leave enough fruit buds on a tree for a good crop.
By November a plump, round bud will have formed which carries the flowers in April and May. The bud scales on fruit buds are typically downy, especially on apples, pears, peaches and nectarines.
In summer, fruit buds are often 'supported' by a surrounding cluster of leaves, perhaps the rosette of a spur, or the tip of a shoot.
Wood or growth buds
Wood or growth buds (i.e. buds carrying leaves but no flowers) are easily distinguished from fruit buds by being slender, pointed buds borne in a leaf axil. These buds are usually much smaller and more insignificant than fruit buds.
This is a typical fruit bud covered in downy scales
These are typical wood or growth buds. They are a lot smaller than fruit buds and are insignificant looking
Identifying tip- or spur- bearing trees
Before pruning apple trees, it is essential to identify fruit buds and the cropping habit of the tree.
There is an added complication with apples, as cultivars fall into three broad groups according to where the fruit bud is produced and the fruit carried; spur-bearers, tip-bearers and partial tip-bearers:
- Spur-bearers produce fruit buds on two-year-old wood, and as spurs (short, branched shoots) on the older wood. This habit gives spur bearers a tidy and compact appearance. Spur bearers are the largest group and include cultivars such as 'Coxs Orange Pippin’, 'Sunset', 'James Grieve', 'Earl, Victoria' ‘Greensleeves', and 'Lanes Prince Albert'
- Tip-bearers produce very few spurs. They are relatively uncommon. Fruit buds are found at the tips of long shoots produced the previous year. The overall appearance of the tree is more untidy than spur bearer and the branches look sparse without spurs. Examples of tip bearers include 'lrish Peach’ and 'Cornish Gilliflower'
- Some cultivars are partial tip-bearers, producing fruit on the tips of the previous year's shoots and also on some spur. Cultivars include 'Bramley's Seedling, 'Discovery' and 'Worcester Pearmain
Any form of pruning that involves shortening shoot tips will reduce the yield of tip-bearing apples, and to a lesser extent, partial tip-bearers. Therefore these forms are subjected to less rigorous pruning than spur-bearing cultivars and are best avoided when restricted forms such as cordons or espaliers are wanted.
Occassionally unusual swellings occur on the tips of apple trees. These are known as bourse shoots (sometimes called cluster bases or knobs). They are swellings at the base of a flower cluster and are not harmful to the tree. These unpromising-looking shoots will bear normal flowers and leaves in subsequent seasons.
Bourse shoots are formed when a bud elongates. The phenomenon is often associated with individual cultivars, but may appear on any apple or pear.
While looking closely at branches and twigs it is a good time to check the health of your trees. Apple canker is worth knowing how to identify and treat if necessary. Infestation by woolly aphid can also lead to knobbly swellings that should be removed if possible at pruning time.