Articles
THE 4TH INTERNATIONAL SYMPOSIUM ON KIWIFRUIT – AN OVERVIEW
I am used to kiwifruit growing in an area that gets some 1700 mm of rain well distributed throughout the year.
It is salutary for me to realise that kiwifruit can be grown with as little as 300 mm annual precipitation if irrigation is also supplied.
Too often, we expect that the ways in which we at home grow kiwifruit, the conditions that we are used to, are the norm.
Wild kiwifruit grow on the edges of cool temperate rainforests in areas of high rainfall and high humidity.
Although the natural habitat gives us some indication of what the plant likes, such conditions are clearly not obligatory.
Management practices can compensate for differences in environment.
It was remarkable to hear of Professor Allan spraying his kiwifruit with water during winter to help achieve sufficient winter chilling, and in the very next presentation hear Professor Shim describe the growing of kiwifruit under rainproof shelters to protect them from excess water, thereby reducing the incidence of serious bacterial diseases.
The question is not how should kiwifruit be grown – the real question is an economic one: do the returns for the crop justify the management techniques required to grow kiwifruit under particular conditions?
Kiwifruit were first grown commercially in New Zealand.
When ‘Hayward’ became the cultivar of choice, management techniques had to be changed because ‘Hayward’ generally carried lighter fruit crops than did the other cultivars then grown, and it responded poorly to spur pruning.
It has a tendency towards biennial bearing and there was thus a need to get it cropping consistently from year to year.
There was a need for rigorous summer pruning and the selection in winter of the following season’s fruiting wood was important because ‘Hayward’ tends to bear on less vigorous wood than do the other cultivars.
Growers in New Zealand did much to develop the pruning methods that suited ‘Hayward’: the outcome was the “replacement cane” system of pruning.
When ‘Hayward’ kiwifruit were grown in other countries, growers initially followed the procedures that had been successful in New Zealand.
They soon realised, however, that the support structures and the pruning methods that evolved in the Bay of Plenty were not always suitable for different environments.
The first large-scale plantings of ‘Hayward’ outside of New Zealand were in California and growing conditions there were very different to those in New Zealand.
Many early plantings failed because it was not realised that kiwifruit vines require intensive management throughout the year, that they are susceptible to winter cold or lack of water or lack of shelter, and that the fruit are easily sunburnt.
The management practices in New Zealand were not really suitable and Californian growers had to compensate for the less vigorous vegetative growth, the high