New Zealand Journal of Crop and Horticultural Science abstracts
Postharvest fruit rots of kiwifruit (Actinidia deliciosa) in Korea
Young Jin Koh
Department of Plant Medicine
Sunchon National University
Sunchon 540 742, Korea
email: youngjin@sunchon.ac.kr
Jae-seoun Hur
Department of Environmental Education
Sunchon National University
Sunchon 540 742, Korea
Jae Sung Jung
Department of Biology
Sunchon National University
Sunchon 540 742, Korea
Abstract The overall disease incidence of postharvest
fruit rots of kiwifruit (Actinidia deliciosa) in Korea averaged 32%,
but the incidence ranged from 5% to 68% in the orchards surveyed. The percentage
of kiwifruit showing internal and external symptoms were 21.9% and 4.9%, respectively,
and an additional 5.2% of the kiwifruit showed both internal and external
symptoms. Botryosphaeria dothidea and Diaporthe actinidiae
cause ripe rot and stem-end rot, respectively, and were identified as the
major postharvest pathogens with average isolation rates of 83.3% and 11.9%.
Incidence of the postharvest fruit rots was closely correlated with ripening
temperatures favourable to the mycelial growth of the major pathogens. Postharvest
fruit rots occurred at all ripening temperatures ≥11°C and maximum disease
incidence was observed at 29°C. No mycelial growth of B. dothideaand
D. actinidiae occurred on potato dextrose agar plates under 11°C
and the optimum temperature ranges for mycelial growth of the pathogens were
26-35°C and 26-29°C, respectively. The optimum kiwifruit ripening
conditions for minimising damage from the postharvest fruit rots were a 20-day
ripening at 17°C. Intensive application of fungicides just before or after
the rainy season is conducted to control postharvest fruit rots in kiwifruit
orchards of Korea. Benomyl WP and thiophanate-methyl WP, registered as preventive
fungicides against postharvest fruit rots, are usually applied 5-6 times
at 10-day intervals beginning in early June in the kiwifruit orchards. Tebuconazole
WP, iprodione WP, and flusilazole WP were selected as alternative fungicides
to prevent emergence of fungicide-resistant strains and reduce the number
of fungicide applications. The optimum spray programme for controlling postharvest
fruit rots was four applications at 10-day intervals from mid June for tebuconazole
WP, iprodione WP, and flusilazole WP, compared with five applications for
benomyl WP and thiophanate-methyl WP.
Keywords kiwifruit; postharvest fruit rot; ripe rot;
stem-end rot
H04095; Online publication date 22 July 2005 Received 12 November 2004;
accepted 22 April 2005
New Zealand Journal of Crop and Horticultural Science, 2005, Vol. 33:
303-310
0014-0671/05/3303-0303 © The Royal Society of New Zealand 2005
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