PROBLEMS ASSOCIATED WITH THE INTRODUCTION OF VIRUS- AND MYCOPLASMA-FREE APPLE TREES TO NEW ZEALAND ORCHARDS

In New Zealand, the introduction of apple trees freed from virus and mycoplasma infection by heat therapy has resulted in higher yields, stronger and better shaped trees, and the elimination of fruit disorders.
Associated problems of excessive growth, and delayed fruit colouration in young trees may be alleviated by the use of appropriate rootstocks, high budding at the time of propagation, and modified tree training.

A problem of poor skin colour on coloured cultivars was initially thought to be a direct consequence of heat therapy.
It now seems more likely to be associated with poor clone selection prior to treatment, or the inadvertant use of buds or shoots which have a concealed reversion to standard colour just before or during the treatment process.

XII International Symposium on Fruit Tree Virus Diseases

G.A. Wood

https://doi.org/10.17660/ActaHortic.1983.130.44