Browsing by Author "Suharban, M"

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    Etiology and control of blight and fruit rot of brinjal
    (Department of Plant Pathology, College of Agriculture, Vellayani, 1991) Jenny John; Suharban, M
    The present investigation was undertaken to evolve an economically feasible management practice against the fruit rot and twig blight of brinjal. Infected plant parts of brinjal showing initial stages of infection were collected from different localities and symptomatology of the pathogen was studied in detail. The pathogen was brought into pure culture and sent to C.M.I. International Mycological Institute, U.K. for identification. It was identified to be Phomopsis vexans (Sacc. & Sydow.) Harter. Pathogenicity of the fungus was studied by inoculating the fruits and stems of the host plants and typical symptom similar to natural conditions were observed. Host range of the pathogen was studied by inoculating the different vegetables with the test fungus. Only carrot and tomato was found susceptible to the pathogen. The fungus grew well equally on potato dextrose host extract and oat meal media followed by Czapek’s and Richards’s media. Good sporulation of the fungus was also noticed in potato dextrose and host extract media, fair sporulation in oat meal and Czape’ks media and no sporulation in Richards’s media. In some cases wavy growth of the pathogen was noticed in potato dextrose agar. In liquid media good mycelia growth of the fungus was observed in potato dextrose, host extract and Czapek’s followed by oat meal and Richard’s media. Culture filtrate of the fungus caused drying of the leaves of the young seedling kept dipped in it and on leaves of matured plants it developed dark brown spots and these leaves dried up eventually. Seed treatment with culture filtrate exerted an inhibitory effect on germination of seeds of brinjal, chilli, tomato and greengram, whereas germination percentage was above 90 in seeds kept in sterile water. There was no difference in germination of seeds treated with culture filtrate fresh and that which was boiled for 10 minutes. The germination of seeds greatly reduced in seeds extracted from infected fruits both in blotter and sand method whereas the germination percentage of seeds extracted from healthy fruit was above 90 per cent. The seedlings raised from infected fruit showed damping off symptom after 2 weeks. Laboratory evaluation of different fungicides revealed that all the fungicides could inhibit the growth of the pathogen. Bordeaux mixture gave complete inhibition of growth of fungus at 750 ppm concertation while bavistin had the same effect at 500 ppm concentration. In field evaluation with different fungicides to control Phomopsis fruit rot it was found that spraying with CoC-50 at fortnightly interval was the best fungicide as the per cent infected fruits were minimum, that is 3.9, followed by Bordeaux mixture, dithane M-45, kavach, calixin, bavistin, and cumin L, with per cent infected fruits being 8.95, 10.7, 14.64, 15.35, 17.04, 20.56 respectively. Seeds of brinjal when soaked in spore suspension for 24 hours showed a reduction in germination compared to those seeds soaked in sterile water for the same period. Seed treatment with different fungicides showed that bavistin was the best fungicide in inhibiting the effect of the pathogen on seed germination followed by dithane M-45, and COC -50.
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    Foliar fungal pathogens associated with yellowing disease of coconut.
    (Department of Plant Pathology, College of Agriculture, Vellayani, 2011) Anju, C; Suharban, M
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    Monographic studies on edible species of pleurotus and standardisation of the techniques for large scale cultivation
    (Department of Plant Pathology, College of Agriculture, Vellayani, 1987) Suharban, M; Chandrasekharan Nair, M
    Mushrooms have long been recognized as a food because of their nutritive value and flavour and hence are grown on commercial scale on many parts of the world. In recent years cultivation of Pleurotus species are becoming popular in many of the tropical areas. No effort has been made in the past to collect, identify, describe and catalogue the Pleurotus mushroom flora of Kerala and standardise the techniques for their large scale cultivation. The present study was therefore initiated to achieve the above objectives. Collection, identification and description of the Pleurotus flora naturally occurred in and around the College of Agriculture and parts of Trivandrum district were carried out with the help of a data sheet. Twenty species of Pleurotus properly identified were further subjected to detailed study. A key was constituted to enable easy identification of gill the twenty described species. Out of the twenty species described, eight species are new records for India. Among the common cultivable species of Pleurotus. P .sajor-caju was found to be the most suitable mushrooms for the warm humid climatic condition of Kerala. The optimum temperature for maximum growth of this mushroom was found to be between 15 to 50 *C. Comparative efficacy of various containers and substrates used for spawn production revealed that Maize and empty wine bottle were the best substrate and container respectively for spawn production. Trials on cultivation of P. sajor-caiu on logs of common trees revealed Mango tree log to be the best in getting higher yield. Polythene bag was found to be the best container in supporting maximum sporocarp formation. Straw of local varieties of rice were better than high yielding varieties of rice in supporting sporocarp, formation. Comparative efficacy of straw made into bits and small twists with six species of Pleurotus revealed higher yield of 775 g per kg of substrate with spawn of Pleurotus- sajor-caju establishing its superiority for cultivation in Kerala. Cultivation of P .saior-caju in different seasons of the year revealed that this mushroom can be successfully cultivated in Kerala all through the year on paddy straw.
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    New leaf blight disease of Catharanthus Roseus(L.) G. Don (L)
    (Kerala Agricultural University, 1981) Padmakumary, G; Suharban, M; Nair, M C; Reghunath, B R; Sreekantan Nair, G
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    New leaf blight of pineapple
    (Kerala Agricultural University, 1993) Suharban, M; Rajan, K M
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    Rhizoctonia Salvinia Molesta Mitchell
    (Kerala Agricultural University, 1981) Padmakumary, G; Suharban, M; Chandrasekharan Nair, M
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    Strain improvement and production technology of milky mushroom (calocybe indica P. & C)
    (Department of Plant Pathology, College of Agriculture, Vellayani, 2006) Heera, G; Suharban, M
    Survey conducted in different localities to obtain the native flora of Calocybe resulted in the collection of ten isolates of Calocybe, seven from Thiruvananthapuram, two from Kollam and one from Pathanamthitta. The nature of growth in petridish and spawn substrate of the native isolates varied widely. Of the ten isolates, the most promising isolate OE-349 which gave better yield, shelf life, nutrient status and low mortality was selected for further studies. Cultural characters studied showed that locally available jackfruit seed kernel broth can be substituted for potato dextrose broth for maximum biomass production. In solid media the Calocybe isolate had fluffy growth in oat meal agar and better radial growth in potato dextrose agar medium. Calocybe preferred fructose, rather than dextrose, hence can be used for higher biomass production. Least preferred carbon sources were lactose and sucrose. Among the nitrogen sources peptone was the best for maximum biomass production. The inorganic source, ammonium salts were less preferred than nitrate source. Calocybe preferred a pH of 5.5 for maximum biomass production. An increase or decrease in pH resulted in the reduction of biomass. Among the various substrates subjected to different sterilisation techniques, spent mushroom substrate (SMS) subjected to solarisation out yielded paddy straw and coir pith, compared to boiling and chemical methods. Solarised SMS gave higher biological efficiency and better fruiting body weight. Mortality percentage was minimum in solarised SMS. Solarised beds of SMS and paddy straw were free from contaminants. Coirpith did not prove as a successful substrate for Calocybe cultivation as it was highly contaminated with Trichoderma. Of the various supplements, rice bran supported higher biological efficiency than others. The application of supplements at four per cent rate gave better yield than two per cent. Rice bran supplementation of solarised SMS out yielded the other supplements neem cake, vermicompost and ferrous sulphate. Neem cake and vermicompost were not suitable for supplementation as there was heavy incidence of Trichoderma on beds. Casing materials consisting of sand, soil and CaCO3 gave better biological efficiency than coir pith soil mixture, vermicompost-soil mixture and clay-soil mixture. Vermicompost and coir pith when used as an ingredient in casing material there was heavy incidence of Trichoderma. Clay-soil mixture did not support fruiting body production of Calocybe due to crust formation as a result of quick absorption and slow release of water. Strain improvement was done using UV rays and gamma irradiation. UV irradiation at two distances (5 cm to 10 cm) from source for different periods (10, 15, 20 and 25 minutes) did not produce any significant effect on the yield as well as shelf life and nutrient status of mushroom. But irradiation at 10 cm from source had a positive effect on nature, radial growth of mycelium and yield when compared to irradiation at 5.00 cm. Irradiation with  rays enhanced yield, nutrient status and shelf life of Calocybe. Irradiation with  ray from 0.5 – 2.5 KR showed an increase in yield upto 1.5 KR followed by a decline. A hybrid was developed by crossing single spores of two different isolates with dissimilar character. The hybrid (54.88 per cent BE) out yielded the parents in yield, characters, nutrient content and enzyme activity. Molecular characterisation of hybrid and their parents revealed that hybrid had 44.40 per cent similarity with one parent and 28.57 per cent similarity with other parent. Dendrogram constructed clustered one parent and hybrid into one group and other parent into another group at 0.26 similarity coefficient.
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    Studies on the leaf spot and post harvest diseases of banana, and their control
    (Department of Plant Pathology, College of Agriculture, Vellayani, 1977) Suharban, M; Paily, P V
    Varietal susceptibility of different cultivars to the leaf spot diseases of banana was studied in an existing plantation, consisting of 18 varieties in the Instructional Farm, Vellayani. It was found that Robusta and Chakkarakeli were the most susceptible while Venattumonthan and Mass being the least susceptible. Different types of leaf spots viz., Cordana leaf spot, Deightoniella leaf spot, Helminthosporium leaf spot, Septoria leaf spot and Cercospora leaf spot were studied, and the fungi associated with them were also isolated, Growth and sporulation of all these fungi were studied in different media. Power oil was observed to be the best fungicide eventhough there was no significant difference between power oil, Difolatan and Bavistin in the fungicidal control of leaf spot diseases. It was found that carbondioxide does not have any role in enhancing the keeping quality. Both partial filling and complete filling of the gas were seem to enhance deterioration. When higher concentrations of benomyl were tried it was found that 600 ppm was superior to all other treatmentsIn 500 gauge polythene bags. Eventhough different fungicides like Bordeaux mixture, benomyl and lime water were tried in different gauges of polythene bags viz., 150, 200, 250, 300, 350, 400, 450 and 500, 600 ppm benonyl in 200 gauge polythene bags was found to be the best in preserving the fruits followed by lime water, and Bordeaux mixture