APPROACH GRAFTING (INARCHING)
This is best attempted by matching up seedlings and scion branches on the ground or on platforms in the canopy. Mr. H. Bosworth of Ingham has devised a technique of surrounding the parent tree with heavy arc mesh and sliding supporting boards through the mesh at desired heights.
Young vigorous seedlings and scion branches are preferred since callusing is rapid and the grafted tree can be detached in as little as 6 weeks. Older wood combinations may take up to 10 weeks to complete the process. The best season is January to April when sap flow is strong and frequent rain obviates hand watering. However it is desirable to provide overhead misting systems.
The scion and stock surfaces are matched - preferably low on the stock and high up on the green/brown wood on the scion. Cut no deeper than one half the thickness of each branch - and for a maximum length of 30 mm. Long cuts (up to 60 mm) callus slowly and often poorly - and allow invasion of fungi. Ties should be tight, but it does not appear to be necessary to provide a water-proof seal and mastic over the tie. If growth of both stock and scion is vigorous, then the stock above the union can be cut off at 4 weeks and the scion below the union cut (notched) to 1/3 scion thickness.
At 5 weeks, cut to 2/3 and at 6 weeks, detach the scion. If growth is slow or the wood very mature at the union, it is safer to delay detachment to 8 to 10 weeks. Then move the grafted plant to a closed, high-humidity bed or mist system, or alternatively, enclose the scion in a polythene bag for 2 weeks. Do not remove ties until the scion has made 300mm of new growth. Then, carefully cut the stubs and paint with cuprox/burnt lime (50/50) slurry. Approach grafting in potted trees is also useful - and very young scion growths can be used with a quick turnover.
DATE: November 1981
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