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Pineapple fruit rot caused by Ceratocystis paradoxa and growth studies on two isolates

Francisca Okungbowa: University of Benin

<div>Pineapple (<em>Ananas comosus</em>) is a tropical fruit and good source of minerals and vitamins. Fruit rot of pineapple caused by <em>Ceratocystis paradoxa </em>is a major fungal disease with huge crop losses. Information on effect of the disease on nutritive value is scanty. The aim of this study was to determine the prevalence of pineapple fruit rot caused by <em>C. paradoxa</em> in some markets in Benin City and evaluate the effect of the pathogen on the nutritive value of the fruit and to study pathogen growth under various environmental conditions, with a view to providing information on disease control. Fifty pineapple fruits were examined for symptoms. Small (5mm) portions were cultured on Potato Dextrose Agar at 28 2<sup>0</sup>C for 7 days, using standard mycological procedures. Two isolates (1 and 2) of <em>C. paradoxa</em> were distinguished on the basis of the cultural characteristics and disease severity. Calcium, manganese, potassium, moisture, vitamin C, protein and carbohydrate contents of infected fruits decreased significantly (p= 0.05) while fibre increased. Optimum growth temperature was 30<sup>0</sup>C for both isolates. All light regimes allowed growth with highest growth at 24hr darkness. Relative humidity of 100% supported the best growth and 55%, the least. The pH affected both isolates differently. The physiological responses of the two isolates to environmental factors need further study. The isolates differed in their ability to incite symptoms; the results therefore provide useful information for planning disease control.</div>