New Zealand Journal of Crop and Horticultural Science abstracts
Growth and fruit quality of ‘Braeburn’ apple (Malus domestica) trees as influenced by fungicide programmes suitable for organic production
J. W. Palmer
S. B. Davies
P. W. Shaw
J. N. Wünsche*
The Horticulture and Food Research Institute
of New Zealand Ltd
Nelson Research Centre
P.O. Box 220
Motueka, New Zealand
email: jpalmer@hortresearch.co.nz
*Present address: The Horticulture and Food Research Institute of New Zealand Ltd, Hawke’s Bay Research Centre, Private Bag 1401, Havelock North, New Zealand.
Abstract Organic pipfruit growers in New Zealand have reported decreased yield and fruit size and poorer quality of foliage of ‘Braeburn’ apple (Malus domestica) with fungicidal programmes based on sulfur. This project aimed to quantify the effect of several fungicide programmes compatible with organic production on the tree growth, yield, and fruit quality of ‘Braeburn’. The spray programmes included Kocide DF, lime sulfur, Kumulus, slaked lime, Kocide DF + slaked lime, and Kocide DF + Kumulus compared to an Integrated Fruit Production (IFP) compatible programme based on dodine, polyram, and captan. The spray programmes were applied from pink tip until harvest, with a total 19 spray applications made to 5-year-old ‘Braeburn’/MM.106 trees. Spray treatments did not influence shoot growth, leaf area development, or increment in trunk cross-sectional area. Leaf photosynthesis was significantly reduced by all treatments which included sulfur (lime sulfur or Kumulus) with reductions of up to almost 50% in January compared to the non-sulfur treatments. At harvest, the pooled data for the treatments containing sulfur showed a significant yield per tree reduction of 12% compared to the non-sulfur treatments, largely as a result of decreased fruit numbers per tree. Treatments containing Kocide DF resulted in a higher proportion of fruit with russet. The addition of Kumulus or slaked lime to Kocide DF resulted in some amelioration of russet. All treatments resulted in less blush development on the fruit compared to the IFP control, except for slaked lime. Slaked lime treatments, however, tended to reduce sunburn. The Kocide DF + Kumulus treatment produced the highest reject rate for low colour. Black spot (Venturia inaequalis) incidence on fruit at harvest was significantly higher on trees treated with either Kocide DF or slaked lime compared to the control treatment. When Kocide DF and slaked lime were used together, however, control of black spot was not significantly different from the control. In contrast, dry eye rot (Botrytis cinerea) incidence was significantly higher on the trees treated with lime sulfur.
Keywords organic production; disease control; leaf photosynthesis
H02027 Received 12 April 2002; accepted 20 February 2003 ; published 12 June 2003
New Zealand Journal of Crop and Horticultural Science, 2003, Vol. 31: 169-177
0014-0671/03/3102-0169 $7.00 © The Royal Society of New Zealand 2003
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