ISHS Acta Horticulturae 422: International Conference on Integrated Fruit Production
USE PATTERNS AND ECONOMICS OF FUNGICIDES FOR DISEASE CONTROL IN NEW ZEALAND APPLES. |
| Authors: | D.W.L. Manktelow, R.M. Beresford, T.A. Batchelor, J.T.S. Walker |
| Abstract:
Ensuring that New Zealand apple production follows environmentally sustainable management practices is a national research priority, achievable partly through reductions and more careful management of pesticide use. Only black spot (scab) and powdery mildew disease control currently depend on routine fungicide applications. Weather-based infection risk predictions are widely used by growers to schedule scab curative fungicide applications. On average 14 to 18 fungicide sprays are applied each season depending on cultivar, district and weather. In a typical spray programme, 80% of fungicides are primarily for scab control and 20% are specific mildewicides. DMI fungicides with additional activity against powdery mildew make up 15% of the scab fungicides. Pest and disease control comprises approximately 20% of direct production costs. Total fungicide costs are approximately 60% of chemical costs. Economic analysis of average scab fungicide use indicates potential for about 25% use reduction before disease could reduce profit. However, growers are risk averse and there is currently little economic incentive for apple growers to reduce fungicide use. The majority of apple growers produce for export through ENZA New Zealand (International) (ENZA). ENZA determines pesticides used on export fruit, sets pesticide withholding periods and operates a random pesticide residue testing programme to ensure that fruit does not violate the residue tolerances of importing countries. All ENZA growers submit spray diaries. Diary analysis has indicated that approximately 10% of growers use far more fungicide than necessary to control disease, even though they do not exceed residue tolerances on their fruit. ENZA, in consultation with HortResearch, has proposed definition of pesticide use targets based on Acceptable Standard Application Practice (ASAP). It is anticipated that gradual reductions of ASAP targets will result in pesticide use reductions by all apple producers. | |
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