Flowering and fruit set of some 'problem' trees can be improved with a little-known method called cincturing.

Cincturing is the procedure of cutting a ring of bark out of the main trunk or branches of trees. It can be used equally effectively by home gardeners or commercial growers, and is particularly useful for shy-bearing litchi and mango trees.

The age old Asian methods of root pruning, driving nails into the trunk and flagellation - that is, beating the branches and trunk - give similar results to those obtained from cincturing.

In Queensland, some Bowen mango growers are reputed to run their tractors into shy-bearing trees, thus causing both root and trunk damage. This is a rough and ready method, but appears to give the desired effect.

All these operations restrict the movement towards the roots of carbohydrates produced in the leaves. This temporarily restricts tree growth, changes the hormone balance, and makes the tree more likely to flower.

Timing of the cincturing operation is critical. For litchi, mango and avocado, April is the best month.

Only trees which have not borne well in the previous year, or a number of years should be treated.

Treat only trees in good health. The best candidates are trees which have shown excessive growth.

To cincture mango trees, use an ordinary hand saw to cut through the bark and cambium layer, but not into the sapwood. The cut should be made between 300 mm and 800 mm above the ground.

Completely encircle the tree with a single cut.

Litchi trees can be treated in the same way as mango trees.

Alternatively, treat litchi by cutting in around half of the branches at the height where the tree divides into six to eight branches. In the following year treat the other branches and thereafter alternate the treatment each year.

Cincturing is particularly useful on seedling avocado trees of three or more years of age. The procedure is the same as for litchis.

With vigorous citrus trees, cincturing may be done year after year.

Cincturing also restricts excessive growth on some citrus trees.

Painting the cut on litchi, avocado and citrus trees with a slurry of equal parts of cuprox and hydrated lime in water reduces the chances of fungus disease getting in through the cut. Cuprox in water without the lime can also be used, but is easily washed off by rain.

Brian Watson, DPI Kamerunga

DATE: May 1981

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