New Zealand Plant Protection 53 (2000): 1-6
Disease management in Hawke's Bay apple orchards converting to organic production
K.G. Tate, D.W. Manktelow, J.T. Walker and H. Stiefel
ABSTRACT
Disease control achieved by 10 apple growers converting to organics during the 1997-98 and 1998-99 seasons is reported. Two orchards experienced black spot outbreaks each season, while the remainder averaged 0.5% spotted fruit. Powdery mildew was severe in 1997-98 but acceptable in 1998-99. Fruit rots after cool-storage averaged 0-11% for different varieties in 1997-98 and 0-30% in 1998-99. Fungicide applications averaged 11.6 in 1997-98 and 18.4 in 1998-99, which was a net increase in chemical use. Copper use was below 3 kg/ha/year. The most-used spray programme was a green-tip copper, three pre-bloom lime-sulphurs, sulphur/copper bloom sprays and sulphur or sulphur/ copper sprays thereafter. Results showed that acceptable disease control is achievable in "organic" orchards, but summer and core rots remain a concern.
Keywords: organic production, apples, disease management, Venturia inaequalis, Podosphaera leucotricha.
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