Application of Ozone to Control Insect Pests and Moulds of Date Fruits

Saeed S. Al-Ahmadi, Reda A. Ibrahim and Salama A. Ouf

Biology Department, Faculty of Science, Taibah University, Medina Munawarah, P.O. 30002 Saudi Arabia.

ABSTRACT: In this study, the effectiveness of gaseous ozone and ozonated water on mycological flora and insect pests of ten date fruit cultivars were investigated. Steady reduction of fungal count was achieved at 8 ppm ozone gas applied for 4 hours in the case of most test plant materials reaching 2.2 – 6.6 as compared to 48.3-126.0 colonies/g, in the case of control. The longer-term exposure (6 hours) was lethal for all contaminating fungi. The elimination of insect pests requires higher ozone doses where the percent infestation at 30 ppm ozone applied for 6 hours ranged from 0.00 to 4.00% as compared with 7.85 and 15.68% in the case of control. Ozonized water applied for 2 minutes, at the same doses was more effective than gaseous ozone form and induced complete elimination of fungi and insect pests. The spore yield of Alternaria alternate, Aspergillus flavus, Paecilomyces divaricata and Penicillium citinum were reduced by 77.88, 81.56, 79.96 and 81.31%, respectively when exposed to 6 ppm for 4 hours. The total mycotoxins produced by Fusarium oxysporum, P. citrinum and A, flavus were significantly reduced on ozonation. The percent of unhatched eggs of Oryzaephilus surinamensis and Cadra furcatella, two of the insect pests manifesting fruit damage, reached 97.26 and 83.67%, respectively at 5 ppm ozone applied for one hour. Treatment of date fruits of different cultivars with ozone resulted in slight missing of some individual sugar fractions from some cultivars and varying reduction on percent relative concentration of sugar components.

KEYWORDS:

Ozone; insect (pests and mould); date fruits

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