บทคัดย่องานวิจัย

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Control of Alternaria infection of fruit of apple cultivar Nittany with calcium chloride and fungicides.

Biggs, A. R.; Ingle, M.; Solihati, W. D.;

Plant Disease Year: 1993 Vol: 77 Issue: 10 Pages: 976-980 Ref: 13 ref.

1993

บทคัดย่อ

Control of Alternaria infection of fruit of apple cultivar Nittany with calcium chloride and fungicides.

Calcium chloride (CaCl2) was tested for its efficacy in reducing the incidence and severity of infection of apple cv. Nittany by Alternaria spp. In 1989, 8 biweekly applications of flake (referred to as CaCl2) or liquid CaCl2 reduced the incidence of rot from 61% in the controls to 27 and 33%, respectively. Dip treatments alone reduced rot incidence to 17 and 12% for the CaCl2 and liquid CaCl2 treatments, and seasonal sprays followed by dip treatment reduced incidence to 5%. Nine CaCl2 sprays, applied biweekly, reduced the incidence of the disease from c. 44% in the controls to 12 and 18% in 1990 and 1991, respectively. Disease severity was reduced from 27 and 14 lesions per fruit in the controls to 9 and 6 lesions per fruit in 1990 and 1991, respectively. In postharvest tests, fruit treated with CaCl2 alone and in combination with iprodione exhibited the lowest incidence and severity of Alternaria rot after 3 and 6 months in refrigerated storage. The best control of Alternaria rot was achieved with 9 seasonal applications of CaCl2 followed by a postharvest dip of CaCl2 alone or in combination with iprodione. Fruit were sampled biweekly beginning in Jul. until harvest to determine the frequency and pathogenicity of Alternaria spp. In 1991, isolation of epiphytic Alternaria spp. was uniform through the growing season, with isolation frequency of 52-72%. Isolation of Alternaria spp. from the same fruit that had been surface-disinfected yielded c. 1-2% in Jul. and increased gradually through the remainder of the season. At harvest, isolation frequency from surface-disinfected fruit averaged 34%. In 1992, isolation of epiphytic Alternaria spp. increased over the season from 22% in Jul. to 69% at the end of Sep. Isolation of Alternaria spp. from surface-disinfected fruit was 2% in Jul. and 11-16% in Sep.