ISHS Acta Horticulturae 448: III International Symposium on Mineral Nutrition of Deciduous Fruit Trees
DECAY AND PHYSIOLOGICAL DISORDERS OF ‘GOLDEN DELICIOUS’ APPLES IN RELATION TO CULTURAL MANAGEMENT AND FRUIT QUALITY |
| Authors: | J.L. Juan, F. Camps, J. Francés, E. Montesinos |
| Keywords: | Storage, apple, management, quality, Penicillium expansum, Pseudomonas fluorescens, biological control, imazalil, folpet, scald, bitter pit |
| Abstract:
Problems of use of chemical treatments in long-term storage of fruits compel researches to improve and to search for alternative/complementary methods. In 1995 a study was conducted in the coastal region of Girona (North-eastern Spain) to evaluate the susceptibility to storage decay in eleven commercial orchards and to assess the effectiveness of the biological control agent Pseudomonas fluorescens EPS 288 against Penicillium expansum. Throughout the growing season, fruit growth, quality and mineral content were assessed. In the first experiment, fruit samples from eleven orchards were submitted to different pre-storage treatments: a CaCl2-Ethoxyquin mixture, CaCl2-Ethoxyquin plus a fungicide mixture (Folpet and Imazalil) and an untreated control. Bitter pit and superficial scald were adequately controlled by the CaCl2-Ethoxyquin treatment in all orchards. Bitter pit incidence in non-treated controls was inversely related to calcium content at harvest and to plant density, and directly related to one-year shoot growth and N content in fruit at harvest. Superficial scald was only present in control and appeared in early harvested fruits. Severe scald was related to low K content in fruit and leaves, and to low titratable acidity on fruits. Low K content in fruit appeared to be linked to excessive crop. In a second experiment, surface disinfected and wounded fruits from all the orchards were inoculated with Penicillium expansum after treatment. Treatments consisted of dipping solutions containing either the fungicide mixture or a 1x108 c.f.u./ml suspension of the biological control agent Pseudomonas fluorescens EPS 288. Diseases were controlled by both the fungicide mixture and the biological control treatments. In control, an inverse relationship was observed between Ca content in fruit at harvest and susceptibility to decay. The results suggest that fruit susceptibility could be also linked to fruit maturity, and to N content in fruits and leaves. | |
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