Pruning and training persimmons

Garth Sanewski, Department of Primary Industries and Fisheries.

Training systems

There are several reasons for training trees to a specific system:

* To allow light into the canopy to improve fruit colour and sugar levels.
* To simplify cultural operations such as pruning, thinning and harvesting.
* To reduce limb breakage and fruit rub.

There is little information available on the suitability of the different training systems for persimmon. We can, however, make some general comments based on limited overseas and local experience.

Open vase

This system has been tried in Australia. Trees are very open and prone to limb breakage and sunburn.

Tatura trellis, Lincoln trellis and their variations

Trellised systems are desirable because they should produce the best quality fruit of all the training systems available. Also, they should help limit tree size so bird netting can be more easily erected.

However, persimmons would probably outgrow these systems in our climate unless widely spaced. Limited overseas work suggests this may be the case.

The development of growth retardants or dwarfing rootstocks would make these systems more feasible. These systems should only be experimental at this stage.

Palmette (trellised or untrellised)

This system should be suitable for trees spaced at about 4.5 m x 3 m. A trellised palmette would be advisable with wires at 50 cm, 100 cm, 150 cm and 200 cm high.

Free standing central leader

This is a fairly inexpensive and simple system to develop. For these reasons it is the system most commonly used. Disadvantages are that trees become fairly tall and, because it is untrellised, limb breakage and fruit rub can be a problem. Spacing will vary with cultivar and soil depth. A suitable spacing for Fuyu on good deep soil is about 6 m x 5 m. Matsumoto-Wase-Fuyu, Century and Ichikikei Jiro could be spaced at about 5 m x 3 m. An example of a persimmon pruned to a central leader is shown in figure 1.

Summary

At this stage of the industry's development, it is suggested that growers adopt a low-cost approach to training systems. Either the palmette or free standing central leader are practical options. The trellised palmette is probably the best of the practical alternatives. Other trellised systems such as the Lincoln and Tatura need to be tested.

Flowering, fruiting and growth patterns

Before you can understand how to prune the persimmon you must understand the growth and fruiting habits of the tree (see figure 2).

Flowers are produced on new growth in the spring period. This new growth emerges from one-year-old wood. We can refer to this one-year-old wood as fruiting wood. It is the light-brown growth you see on trees in the dormant period (winter).

The best fruiting wood is about 1 cm thick and 30 cm long. It usually has about ten buds. The end four to six buds will produce new growth in September to October, and these will have flowers. This is what we refer to as a 'tip-bearing habit'. The bottom two to three buds will produce weak non-bearing laterals. These weak laterals usually die out.

The flowers will be produced in the bottom (first) few leaf axils of the new growth. Many of the flowers will be shed or must be thinned out to leave one to two fruit per lateral.

Vegetative growth will continue until about December. You may get a second summer flush in vigorous or young trees. The spring growth which is carrying fruit will produce flowers towards the tips the following season.

If no pruning is done the fruiting wood will be produced further and further away from the main leader. There will be more but smaller fruit. Because fruit is produced on the ends of fruiting arms, limb breakage and fruit damage would be more likely.

Pruning young trees

The aim of pruning in the first three to four years is to develop the main framework of the tree.

A grafted persimmon tree, as obtained from a nursery, usually consists of a single stem. Pruning is needed to encourage a strong central leader with tiers of branches at about 70 cm intervals up to the trunk. The usual times to prune are August and late November.

The first pruning is just after planting. If there is no branching within 50 cm of the ground, cut the single stem at that height. If the central leader is not the highest point, the tree should be pruned to ensure it is (see figure 3).

Over the next two to three years the central leader should be pruned about ever 70 cm to encourage branching at those positions. Long laterals should also be tipped back. Prune out strong growths that are not needed. Always ensure the basic shape of the tree is developed without branches crowding one another. Avoid severe pruning as it only induces excessive growth at the expense of fruiting.

Pruning bearing trees

The main aim of pruning a bearing tree is to prevent the development of long drooping leaders. It also helps to keep the tree open and manageable. Pruning is normally done once per year, in late August. The procedure is as follows:

* Prune off low shoots and suckers.
* Break of any dead wood within the canopy.
* Prune out strong growths not needed.
* Prune back long laterals to about 70 cm or so.
* Prune out some laterals if too crowded.
* Prune some fruiting arms back to one or two laterals closer to the main leader as shown in figure 4. Don't do this to all fruiting arms but rather keep a balance of old and new fruiting arms. Replacement of fruiting arms shouldn't be needed until about year 4 or 5, but every year from then onwards.

Trees may need to be lightly tipped in late November if they are vigorous. If the trees are vigorous, the fertiliser programme should also be adjusted to reduce vigour.

Because persimmons have a tip-bearing habit you should be careful not to tip fruiting laterals back too much.

Pruning cuts over about 20 mm in diameter should be treated with a white water-based paint containing a mould inhibitor.

Crop thinning

Trees can go into a biennial bearing habit if allowed to crop very heavily in any one year. Fruit size will also be reduced if trees set heavy crops. Fuyu requires about 15 leaves per fruit to give adequate size. Insect damage is increased where fruit forms tight clusters.

To avoid these problems, remove a part of the crop in October, just after fruit set. Remove the fruit closest to the base of the shoot as these are more likely to be shed. Only one fruit should be left on most laterals. Laterals longer than about 200 mm could carry two or three fruit as long as they are well-spaced.

Figure 4. Pruning fruiting arms on bearing trees.

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Information contained in this publication is provided as general advice only. For application to specific circumstances, professional advice should be sought. The Department of Primary Industries and Fisheries, Queensland has taken all reasonable steps to ensure the information in this publication is accurate at the time of publication. Readers should ensure that they make appropriate inquiries to determine whether new information is available on the particular subject matter.

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Last updated 04 February 2004