Chestnut Survey discovers North/South differences

Chestnuts are not all the same, and important points such as quality and performance can depend on whether they are derived from North or South Island cultivars, and where they are grown. A recent nationwide survey of chestnuts could provide important information for the commercial future of chestnuts in New Zealand.

HortResearch scientist David Klinac said chestnut performance under NZ conditions varies greatly, depending upon location and cultivar.

With the present enthusiasm for chestnut planting, and an increasing demand for chestnut trees, the following questions are often asked: which cultivars should I plant and where should I plant them?

"While there is local, anecdotal information available, and given the diverse origins of our chestnut selections, and some of the peculiarities of chestnut reproduction, neither of these questions has yet been addressed in a systematic matter for New Zealand as a whole," Dr Klinac said.

The aim of the survey, carried out by the Kernel Chestnut Co-op, the South Island Chestnut Action Group and the NZ Chestnut Council and involving HortResearch's Dr Klinac at Ruakura, staff at Lincoln University and growers from throughout New Zealand, was to address these questions.

The main focus was on issues of nut quality, especially susceptibility to storage rot fungi like Phomopsis.

The survey found significant North Island/South Island differences in chestnut performance, and significant regional variation within both North and South Islands. North Island derived selections grown in Canterbury, under the drier, less rot-prone climate, had nut quality significantly different to that of the same cultivars grown in the North Island. This appeared to be also true in reverse; with South Island derived chestnut cultivars all performing differently when grown in the North Island.

Perhaps the single biggest, most important regional difference noted was the confirmation of much lower incidence of internal Phomopsis rot in the drier producing regions (lower humidity/rainfall after flowering and harvest) though sometimes at the expense of nut size and yield. This could be of major importance to the commercial future of chestnuts in NZ requiring specific chestnut cultivars to be matched to specific growing regions and climates.

"Although this survey highlighted a number of points it has also left many questions unanswered. Consequently, in future years, it is hoped to expand this survey to include tree growth, tree health, tree age, yield and time of flowering”, Dr Klinac said.

Funding for the survey was provided by AGMARDT.

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