Browsing by Author "Jayasinghe, C.K."

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    Cell wall degrading enzyme secretion by Cylindrocladium quinqueseptatum
    (Rubber Research Institute. Agalawatta, 1999) Jayasinghe, C.K.; Wijesundera, R.L.C.
    Cylindrocladium quinqueseptatum causes leaf fall of clove in Sri Lanka and is responsible for the leaf spots of rubber in Malaysia.only one isolate (KP)from four pathogenic isolates examined secreted polygalacturanase(PG) when grown in liquid media.None ofthe isolates secreted pectin lyase(PL).The extracts of clove and rubber leaf tissues,inoculated with the KP isolate did not show any PG and PL activity .The leaf tissue did not have the ability to ingibit c.quinqueseptatum PG produced in culture.All isolates of C.quinquesepltatum secreted cellulases viz.cellobiase and b-glucosidase in culture.cellobiase was detected in the inoculated rubber leaves,The levels of B-glucosidase,an ingerent enzyme of Hevea leaves,also increased rapidly following infection.The results indicate that pectic enxymes play a minimal or no role in disease developmet of C.quinqueseptatum infecton in cloves and Hevea.Thus cellulolyic enzyme probably play a nutritive role.
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    Cell wall degrading enzyme secretion by Cylindrocladium quinqueseptatum
    (Rubber Research Institute:Agalawatta, 1999) Jayasinghe, C.K.; Wijesundera, R.L.C.
    Cylindrocladium quinqueseptatum causes leaf fall of clove in Sri Lanka and is responsible for the leaf spots of rubber in Malaysia.only one isolate (KP)from four pathogenic isolates examined secreted polygalacturanase(PG) when grown in liquid media.None ofthe isolates secreted pectin lyase(PL).The extracts of clove and rubber leaf tissues,inoculated with the KP isolate did not show any PG and PL activity .The leaf tissue did not have the ability to ingibit c.quinqueseptatum PG produced in culture.All isolates of C.quinquesepltatum secreted cellulases viz.cellobiase and b-glucosidase in culture.cellobiase was detected in the inoculated rubber leaves,The levels of B-glucosidase,an ingerent enzyme of Hevea leaves,also increased rapidly following infection.The results indicate that pectic enxymes play a minimal or no role in disease developmet of C.quinqueseptatum infecton in cloves and Hevea.Thus cellulolyic enzyme probably play a nutritive role.
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    Changing scene of the disease scenario of the rubber tree in Sri Lanka. history and current status
    (Rubber Research Institute of Sri Lanka:Agalawatta, 2009) Jayasinghe, C.K.
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    Check list of rubber diseases presently distributed in the world
    (Rubber Research Institute of Sri Lanka:Agalawatta, 2001) Jayasinghe, C.K.
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    A comparative study of Colletotrichum species causing anthracnose in Hevea
    (Rubber Research Institute:Agalawatta, 2009) Jayasinghe, C.K.; Fernando, T.H.P.S.; Jayawardana, N.
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    A comparative study of Colletotrichum species causing anthracnose in Hevea
    (Rubber Research Institute. Agalawatta, 2009) Jayasinghe, C.K.; Fernando, T.H.P.S.; Jayawardana, N.
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    Corynespora leaf fall and future of the leading rubber clones in the world
    (Rubber Research Institute of Sri Lanka:Agalawatta, 2002) Jayasinghe, C.K.
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    Corynespora leaf fall. the most challenging rubber disease in Asian and African continents
    (Rubber Research Institute:Agalawatta, 2000) Jayasinghe, C.K.
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    Corynespora leaf spot disease of rubber (Hevea brasiliensis) - a new record
    (Rubber Research Institute. Agalawatta, 1986) Liyanage,. A De S.; Jayasinghe, C.K.; Liyanage, N.I.S.; Jayaratne, A.H.R.
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    Corynespora leaf spot disease of rubber (Hevea brasiliensis) - a new record
    (Rubber Research Institute of Sri Lanka:Agalawatta, 1986) Liyanage, A. De S.; Jayasinghe, C.K.; Liyanage, N.I.S.; Jayaratne, A.H.R.
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    Cross inoculation of Bradyrhizobia among three common legume cover crops in rubber plantations of Sri Lanka
    (Rubber Research Institute. Agalawatta, 1989) Jayasinghe, C.K.; Wettasinghe, S.
    Mixtures of legume cover crops are common in rubber plantations of Sri Lanka during the immature phase of rubber, and changes in ther composition occure with the changes in environment conditions due to the growth of canopies in rubber plants. Bradythizobial isolates from Pueraria phaseloides and desmodium ovalifolium were able to nodulate both legumes, but non of the isolates, including CB 756 (C.S.I.R.O collection, Queensland) produced nodules on Mimosa invisa.
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    Cultural characteristics and reproductive morphology of Geotrichum sp.. a guide to distinguish Geotrichum from Rigidoporus microporus
    (Rubber Research Institute:Agalawatta, 1998) Jayasinghe, C.K.; Wettasinghe, J.L.P.C.
    Culture characteristics of Geotrichum sp. isolate IMI 354411, a fungus responsible for the saprophytic colonization on Hevea roots are described. It was also shown that this fungus could be easily distinguished from Regidoporus lignosus, a devastating pathogens of Hevea roots, by the zonate and cloudy appearence of its colonies on malt agar with a cream undersurface and the disarticulating hyphae which later break upto arthric conidia.
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    Cultural characteristics and reproductive morphology of Geotrichum sp.. a guide to distinguish Geotrichum from Rigidoporus microporus
    (Rubber Research Institute. Agalawatta, 1998) Jayasinghe, C.K.; Wettasinghe, J.L.P.C.
    Culture characteristics of Geotrichum sp. isolate IMI 354411, a fungus responsible for the saprophytic colonization on Hevea roots are described. It was also shown that this fungus could be easily distinguished from Regidoporus lignosus, a devastating pathogens of Hevea roots, by the zonate and cloudy appearence of its colonies on malt agar with a cream undersurface and the disarticulating hyphae which later break upto arthric conidia.
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    Cultural characteristics and reproductive morphology of Geotrichum sp.. a guide to distinguish Geotrichum from Rigidoporus microporus
    (Rubber Research Institute:Agalawatta, 1998) Jayasinghe, C.K.; Wettasinghe, J.L.P.C.
    Culture characteristics of Geotrichum sp. isolate IMI 354411, a fungus responsible for the saprophytic colonization on Hevea roots are described. It was also shown that this fungus could be easily distinguished from Regidoporus lignosus, a devastating pathogens of Hevea roots, by the zonate and cloudy appearence of its colonies on malt agar with a cream undersurface and the disarticulating hyphae which later break upto arthric conidia.
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    Cylindrocladium leaf spot disease of rubber. a review on the causative agent
    (Rubber Research Institute:Agalawatta, 2000) Jayasinghe, C.K.
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    Cylindrocladium quinquesptatum. cultural characteristics and reproductive morphology of the clove isolate IMI 342173 from Sri Lanka
    (Rubber Research Institute of Sri Lanka. Agalawatte, 1996) Jayasinghe, C.K.; Wijesundera, R.L.C.
    Cylindrocladium quinquesptatum boeddijn and reitsma, is a destructive pathogen of eugenia caryophyllata (clove) and is identified as a potential pathogen of hevea barasiliensis in Sri Lanka. Further, the fungus infescts a number of ornamental and forest trees. We report using photomicrographs the cultural characteristics abd the morphology of the reproductive structures; condida, vesicle, stipe, phialides, chlamydospores and microsclerotia of clove isolate IMI 342173. Our investigations demonstrates that the isolate IMI 342173 from Sri Lanka resembles the isolates of C. quinqueseptatum obtained from different hosts in other parts of the world.
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    Diurnal variation in nitrogenase activity of common cover crops in rubber plantations of Sri Lanka
    (Rubber Research Institute. Agalawatta, 1989) Jayasinghe, C.K.; Parker, C.A.; Kulasooriya, S.A.
    Diurnal fluctuations in nitrogenase activity (acetylene reducing activity) have been observed in several nitrogen fixing systems. All experimental plants viz. P. phasides D. ovalifolium and M. invisa demonstrated diuanal rhythm withlight intensity. The lowest acetylene reduction activiteswere detected around midnight and they were activelyu fixing nitrogen by 8.00 am. M. invisa responded to high soil temperature in addition to light intensity. A marked drop in acetylene reduction activity was observed by about 4.00pm when the soil temperature was around 38C
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    Economical and less hazardous fungicide for the management of white root disease
    (Rubber Research Institute. Agalawatta, 1997) Jayaratne, R.; Jayasinghe, C.K.; Wettasinghe, P.C.
    Rigidoporus lignosus, the causal agent of white root disease is the most destructive root pathogen of Hevea brasiliensis in Sri Lanka.presently 5-8% of the cultivated lands are affected with this deadly disease and are under bare patches. The recommended fungicides in Sri Lanka,Pentachloro nitrobenzene (PCNB)and Pentachloro phenol (PCP),were prohibited due to high mammalian toxicity and the fungicides of the triazole family which are being recommended in other countries such as Malayasia and Ivory Coast are not acceptable to Sri Lankan rubber growers due to the high costs of these chemicals. The observations of experiments carried out with less toxic chemicals revealed that 8-10% phenol in bituminous base could be used as an effective fungicidal "Collar protectant"in the management of white root disease in Sri Lanka.In this paper the econimics and the toxicological impact on the environment are also discussed.