A large percentage of fruit trees sold are grafted onto field-grown rootstock. That is, the seedlings are grown in open ground until they are from 1 to 2 years of age when they are grafted. Several more months pass before the grafted portion reaches a size sufficient to be marketed.

The trees are then dug up and potted, but in the process all roots extending more than 15 to 20 mm from the base of the tree are cut off. The removal of the major root system can lead to severe problems later in the tree's life, particularly in cyclone-prone areas such as North Queensland. The effect is not so great on citrus (which have mainly a fibrous root system) as it is on many other species such as Pecan, which normally have a large tap root.

Cutting the root of a tree has the same result as cutting a limb - it causes branching - thereby reducing the size of the root and its ability to anchor the tree.

With many species, grafting onto field-grown seedlings and later cutting the roots has little or no advantage over marcots, which we know from experience in North Queensland are prone to be blown over, particularly when high winds follow rain.

I believe we should be looking more towards grafting smaller pot-grown seedlings and planting them out at a much younger age. These trees will produce fruit in about the same time as the larger ones, but will have the advantage of a complete root system.

DATE: November 1986

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