STUDIES ON FRUIT ROT OF POMEGRANATE ( Punica granatinm L ) CAUSED BY Phytophthora Palmivora ( Butl.) Butl.

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Date
1988
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Mahatma Phule Krishi Vidyapeeth, Rahuri.
Abstract
Pomegranate is one of the important fruit crops, being grown on increasing area day by day in Maharashtra. During the year 1936, a new fruit rot disease was found tc cause severe damage in pomegranate orcnards around Pune. Studies were, therefore, undertaken on this disease with a view to find out suitaole chemical control measures. The affected samples of brown fruit rot from Chamoali village of Purardar taluka in Pune district after isolation yielded a fungal isolate which was obtained in pure culture and used for further studies. Pathogenicity of the isolate was found to be hugnly virulent causing quick rot of pomegranate fruits at a .liferent stages of their development. The organism was studied in detail- for its morpholo gical, cultural and physio logical characters. The mycelium was coerocytic, broad with knots., ' It pro duced lemon shaped sporangia which germinated both by direct and indirect method with . • optimum temperatures 30c and 20°C respectively. The organism was identified as Phytophtho palmivora (Butl.) Butl. at the Commonwealth Mycological Institute, Kewsray, Engl am. It grew well and sporulated in abundance on oat meal agar and Sabouraud's agar. Amongst all other carbon sources sucrose ana fructose gave the best results. Ammonium phosphate and ammonium sulphate were the best inorganic nitrogen sources in comparison with organic sources. Vitamins like riboflavin and biotin supported good growth and sporulation. The organism produced extra cellular enzymes like erepsin, trypsin, diastase, cytase, amidase and gelatinase. Optimum pH for the growth and sporulation was 5.7 with a tolerance range between 3.2 to 8.5- Optimum temperature was 25 C with 10 C to 32.5°C as the growth range. per cent relative humidity favoured -the. the rapid development of/disease. The organism was proved to be pathogenic on 16 hosts including fruits of apple, banana, chiku, lemon, orange, papaya, vegetable fruits like bhendi, orinjal, bitter gourd, little gourd, chilli, pea, tomato, potato and sweet potato. Borueaux mixture at 0.5% and l.0% concentration and riaomil/at 0.05% and 0.1% concentration gave a full control of the disease.
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