Two-year-old wood and young spurs produce the most and best Packham pears.
The largest and best quality apples and pears grow on two-year-old wood and young spurs. To develop two-year-old wood, prune trees according to the 1-2-3 rule of renewal pruning. This rule ensures that the fruiting wood remains young and productive. Your trees are as young as the fruiting wood. Using a pear tree as an example, here is how you use the 1-2-3 rule.
1. The 1 of the 1-2-3 rule refers to the one-year-old laterals, also called pencils. These laterals are 300 to 400 mm (12 to 16 inches) long and a little thinner than a pencil. The buds at the tips are often fruit buds (Figure 1). Never shorten these laterals. If you have too many, space them out and keep the ones that are horizontal and almost as thick as a pencil.
Remove the strong upright shoots and long laterals without fruit buds at the tips. These are nonproductive growth shoots. However, some pear varieties, such as Forelle and Beurre Bosc, often do not produce one-year-old laterals with fruit buds at the tips. If left untipped, these laterals will bud up in the second year.
Also remove the very thin laterals, because these will not produce the quality and sizes of fruit that the market wants.
About one-third of the renewal wood should be one year old.
(On young, nonbearing Bartlett and Forelle trees on Open Tatura [with 2,000 trees per hectare or 800 trees per acre], we have used Ethrel sprays in mid- and late summer to terminate extension growth of laterals. This method of vigor control often resulted in laterals setting terminal fruit buds. Ethrel was sprayed (without a wetting agent) at the rate of 300 to 700 millilitres per hectare (4 to 10 ounces per acre) three to five times. The differences in rates depended on the temperature in the orchard after spraying. A low rate was used when it was hot, and a high rate when it was cool. The active constituent of Ethrel was 480 grams per litre of ethephon.)
2. The 2 in 1-2-3 refers to fruiting wood that is now two years old. This two-year-old wood has had one or more pears at the tip last year and has now spurred up. The fruit bud at the tip has also grown one or two bourse shoots (Figure 2).
How you prune this two-year-old wood depends on the number of buds and the vigor of the trees. Here are two options:
• Cut back to the “ring.” This is the division between the one- and two-year-old wood. This cut is called the “ring” or “fertility” cut, because it improves fruit set (Figure 2, A).
• Cut deeper than the ring to reduce the number of fruit buds. Often you find differences in the fruitfulness of this wood on the same tree. Cut deeper when the wood is weaker (Figure 2, B).
About one-third of the renewal wood should be two years old.
3. The 3 in 1-2-3 refers to three-year-old wood which was cropped when two years old and sometimes one year old. Renew the three-year-old wood by cutting it back hard (Figure 3). This way you will generate new laterals, and the cycle starts again (Figure 4). You may leave some good young fruiting spurs on this three-year-old wood, but you must cut back hard to get new laterals.
About one-third of the renewal wood should be three years old.
The 1-2-3 rule of renewal pruning is simple and less expensive than spur pruning, and it ensures that your trees do not develop old, tired spurs that produce fruit of poor quality and size. This rule also avoids biennial bearing, provided there has been adequate cross-pollination.
The 1-2-3 rule is very effective if you keep your trees calm. Calm trees have dominant leaders that are not forked and have stubs and small secondary branches that carry the one-, two-, and three-year- old wood.
Figure 1: Sequence of wood renewal. This 1-year-old lateral is the foundation of your fruiting wood. Do not shorten it. Keep your trees healthy and moderately vigorous, so you will always have plenty of laterals to choose from.
Figure 2: Two-year-old wood has set several pears at the tip end. Cut the wood at the ring (A) or deeper (B,) depending on the length and thickness of the wood, the number of the buds, and the vigor of the tree. Either cut will enhance fruit set and fruit size.
Figure 3: This 3-year-old wood was cropped when in it was one and two years old. It was cut back deeper than the ring. The three buds behind the cut have set fruit shown by the swelling (bourses) and bourse shoots. The buds on the bourses are of little value, because they are not fruit buds. Cut this piece back to (C) to generate new laterals.
Figure 4: The 3-year-old wood has produced two laterals. You could keep one of both laterals. They cycle of wood renewal can start again.
Van den Ende is a tree fruit consultant in Australia’s Goulburn Valley.