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New Zealand Journal of Crop and Horticultural Science abstractsH00023 Received 31 July 2000; accepted 30 September 2000
Determining whether natural spread of apple green crinkle disease occurs, its absence from New Zealand clonal apple rootstocks, and the sensitivity of some new cultivarsG. A.WOOD
The Horticulture and Food Research
Abstract In an investigative trial to determine if natural
spread of apple green crinkle occurs, six trees of Malus domestica
Borkh. `Granny Smith' free from this disease and other diseases of a virus or
virus-like nature were planted in 1973 in a rectangular block on a Nelson, New
Zealand, research orchard and surrounded by eight trees of the same cultivar
infected with moderate green crinkle and six trees with severe green crinkle.
Two of the healthy trees had been removed by 1987, but the remaining four were
still free from green crinkle after a 20-year period in 1993, indicating that
any insect vectors capable of spreading the disease are unlikely to be present
in New Zealand. In another investigation, no infection with green crinkle
disease was found in `M9', `M26', `Merton 793', and `M106' clonal apple
rootstocks tested from two commercial nurseries engaged in propagating these
rootstocks. As a result of inoculation by chip-budding, two apple cultivars
released from the HortResearch apple breeding programme (`Pacific Queen' and
`Southern Snap'), and promoted by the New Zealand fruit growing industry, were
found to be sensitive to green crinkle disease. |