Macadamia topworking - worth the effort?

The technique of changing one variety of macadamia tree into another by “topworking” is getting some attention again in South Africa. But is it worth the effort? Let’s look at the issues.

[@patrickrushton2046]

Hi Daniel, long time lurker, I thought it was about time I added my 2c. Thanks for covering many different topics relating to macadamia farms. I look after a farm in the northern rivers.
From my experience, top working the trees and then grafting on a new variety have been unsuccessful due to wind damage breaking off the newly grafted wood, even after 2 years of growth. South Africa must have a calmer climate. Sunburn to the trunk of the tree being grafted to, Root death and wood rot from lack of photosynthesis from the new graft and nurse branches. The trees in question were about 30 years old, owns choice on H2 rootstock. They have since been removed completely and replaced.

[@kdegraa]

Thanks for sharing this. I would have thought top working would work but there are many factors that make it difficult for the grafted tree to survive.

[@nutkinfarm]

Hi Patrick. The most valuable 2 cents I've seen in some time - sincere thanks. Experience is so valuable. In this case it confirms my fears. I should add - for completeness - that Chris Searle advocates painting the topworked stumps with white acrylic paint to prevent sunburn.

[@patrickrushton2046]

From memory, I painted the new graft and the exposed trunk when the graft was done. These parts of the tree hadn't seen direct sunlight in many years.
From experience and discussion with others, Macadamia trees should be progressively re-hardened to the full exposure of the sunlight. UV protection sprays such as a wetable clay, envy etc, are a good solution if taking out trees/rows immediately and the remaining trees hadn't had time to re-harden to the sunlight especially if they have not seen full sunlight in years. Try to do any canopy work over winter or early spring as it helps to reduce the risk of sunburn. If a macadamia tree gets badly sunburnt (leaves or bark)it can take years for it to regrow fresh leaves instead of producing nuts, or the bark can split and fall off making it easier for borers to burrow in.

[@GR19611]

Blancmange, living on the ceiling. I thought the song had a good dance beat though.😊

[@nutkinfarm]

Oh Golden, I knew we were kindred spirits! Yes, I admit I did dance to it, back in the day.