Journal of the Rubber Research Institute of Sri Lanka
Permanent URI for this collectionhttps://dl.nsf.gov.lk/handle/1/8676
Browse
10 results
Search Results
Item Penta chloro phenol - effective and economical fungicide for the management of white root disease caused by Rigidoporus lignosus in Sri Lanka(Rubber Research Institute of Sri Lanka. Agalawatte, 1995) Jayasinghe, C.K.; Jayasuriya, K.E.; Fernando, T.H.P.S.Item In vitro antagonism caused by some species of fungi on Rigidoporus lignosus(Rubber Research Institute. Agalawatte, 1996) Jayasuriya, K.E.; Deacon, J.W.; Fernando, T.H.P.S.Fungi potentially antagonistic to rigidoporus lignosus were isolated from a) by placing soil samples on agar plates previously colonized by R.lignosus, or on trichoderma selective agar and b) from basidiomycete fruit bodies in rubber plantations.Modes of action of potential antagonists against R. lignosus were evaluated by in vitro methods viz: production of volatile or non-volatile inhibitory compounds and ability to overgrow colonies of R. lignosus an agar. Some trichoderma spp. were strongly antagonistic to R. lignosus in most of the tests. T. longibrachiatum (isolate DZE10) completely inhibited R. lignosus an agar by producing volatile inhibitory metabolites. Trametes sp. producing volatile inhibitory metabolites. Trametes sp. (isolates ISO16 KIR8) antagonized R. lignosus on dual membered plates.Item Phytophthora epidemics - possibility of management using resistant clones(Rubber Research Institute of Sri Lanka. Agalawatte, 1996) Jayasinghe, C.K.; Jayaratne, A.H.R.Item Weakening effect of 2-furaldehyde on Rigidoporus lignosus the cause of white root disease of rubber(Rubber Research Institute of Sri Lanka. Agalawatte, 1996) Jayasuriya, K.E.; Deacon, J.W.; Fernando, T.H.P.S.Furfuraldehyde is recognized as a potential fumigant which has the ability to weaken rigidoporus lignosus in artificially or naturally infected rubber root inocula. Addition of sulphur to soil at 100 g per 75 Kg of soil, inactivated or prevented the formation of R. lignosus mycelial cords from artificially or naturally infected inocula. Drenching 2.4 per cent aqueous solution of furfuraldehyde in to soil (1 liter/75 Kg) where R. lignosus inocula were buried, caused weakening or inactivation of R. lignosus in artificially or naturally infected inocula. However, combination of two treatments had no ssynergistic effect on both types of R. lignosus inocula in soil.Item A study of isolates of Rigidiporus lignosus. the causative agent of the white root disease of rubber(Rubber Research Institute. Agalawatta, 1991) Wijesundera, R.L.C.; Prelis, S.P.; Liyanage, N.I.S.Rigidporus lignosus (Klotz.) Imazaki cause the whiteroot disease of rubber (Hevea brasiliensis). Five isolates of the fungus, T1, 01, S1, F1 H2, obtained from different rubber growing districts of Sri Lanka, were examined for their growth patterns in different solid media. The secretion of cell wall degrading enzymes was also studied in the isolates T1, S1 H2 when grown in different media with different sources of carbon. The isolate T1, which is known to be the most virulent, grew fast densely on nutrient rich solid media such as potato dextrose agar (PDA) malt extract agar (MEA), but its growth was poor on Czapek Dox agar, Knop-Glucose agar the medium for wood rotting fungi. The other four isolates also grew best on PDA MEA, but the growth was less than that in T1. The growth of S1, O1, F1 H2 on the other media however, was more than that of isolate T1. All isolates except T1 formed branched, strand-like aggregations when growing on solid media. Statistical analysis of the growth studies indicated that a significant difference existed among the isolates also between the isolates the media. The isolate T1 secreted polygalacturonase, pectin lyase, B-glucosidase cellobiase. In T1, the secretion of all the enzymes occurred earlier the amount of enzyme secreted was also higher than in the other two isolates. No polygalacturonase, however, was detected when T1 was grown in the medium with the water insoluble component of rubber roots as the main source of carbon. The pH for optimum activity of polygalacturonase was 6.5 while that for pectin lyase was 10.0.Item South American leaf blight - an overview(Rubber Research Institute. Agalawatta, 1977) John, C.K.; Kadir, A.A.; Subramaniam, S.Item Studies on the variability and pathogenicity of Rigidoporus lignosus(Rubber Research Institute. Agalawatta, 1977) Liyanage, G.W.; Liyanage, A. De S.; Peries, O.S.; Halangoda, L.White root disease in Hevea, caused by the fungus Rididoporus lignosus (Fomes lignosus) occurs widely in Sri Lanka, In recent years, the severity of the disease has increased alarmingly. One of the factors that could be attributed to the increased incidence of the disease is the virulence of the pathogen. This paper report the results of laboratory experiments on the effects of pH, temperature, light and dark, and relative humidity on a number of isolates, obtained from sites located in different rubber growing areas. The fungus is able to grow over a wide range of temperature with maximum growth being recorded at 30ºC. All the isolates grew better when kept in continuous darkness except one isolate which grew equally well under both light and dark conditions. There was wide variability in the pH requirements for the growth of the fungus. The virulence of the different isolates was examined using healthy rubber roots under laboratory conditions and rubber seedlings in pot culture. The results show that there are differences in virulences and pathogenicity.Item The impact of ecological, cultural and biological factors on the strategy and costs of controlling root diseases in tropical plantation crops as exemplified by Hevea brasiliensis(Rubber Research Institute. Agalawatta, 1977) Fox, R.A.Profitability and the availability of financial, material and manpower resources are studied before starting a commercial enterprise; the longer its term, the more complex the studies. The costs of controlling plantation diseases ( in the tropics or leaf diseases), predictably annual (seasonally induced, juvenil leaf), or perennial (root diseases). Especially in the case of root diseases, the pattern of investment, and hence profitabillity, can be affected by the choice of control measures and their timing, factors which must be evaluated by plant pathologists. These factors are examined in general term and with particular reference to effects on them of some aspects of the ecological, cultural and biological control of major root disease pathologens of some tropical plantation crops, Armillariella (Armillaria) mellea, Ganoderma philippii (pseudoferreum), Phellinus (Fomes) noxius, and Rigidoporus (Fomes) lignosus.Item Investigations on new fungicidal systems for control of bark rot on Hevea brasiliensis(Rubber Research Institute. Agalawatta, 1977) Liyanage, A. De S.; Nadarajah, M.; Liyanage, G.W.; Dantanarayana, D.M.The efficacy of Bark Rot fungicides is significantly impared by frequent rains. The present investigation was therefore undertaken to examine the possibility of increasing the efficacy of panel fungicides by incorporating them in rubber latex. Several didithiocarbamates containing metal ions, chemicals such as zinc oxide and formaldehyde and fungicides recommended for Bark Rot control were used singly or in combination, in in vitro trials. Zinc oxide and Zinc dithiocarbamates were of limited use, while others gave satisfactory results. The influence of rubber serum, on the activity of the chemicals and fungicides was then examined. It was shown that all the materials tested except Ziram inhibited te growth of the fungus. Prevulcanised latex was not found to be suitable as an adjuvant under laboratory conditions. However, satisfactory result were obtained when fungicides were incorporated into high ammonia field latex and high and low-ammonia centrifuged latex. The use of preserved latex as an adjuvant with Antimucin and Thiram (TMTD), singly or in combination, was investigated under field conditions. Infection occurred on tapping panels which were inoculateed after removal of scrap, although fungicides were applied prior to inoculation. Disease also occurred on panels, when the inoculum was removed a week after inoculation, but its spread was arrested when fungicides were applied, indicating that continued applications of fungicides could limit the spread of the disease. Panels which were tapped and protected with Antimucin at the time of collection of latex, when inoculated 4 hours later, without removal of scrap, showed less infection. The significance of these findings, in relation to the control of Bark Rot and the influence of these fungicides on the yield are discussed.Item Saprophytic colonization of Geotrichum sp. on Hevea brasiliensis roots, a condition that resembles white root disease(Rubber Research Institute. Agalawatte, 1996) Jayasinghe, C.K.; Wettasinghe, J.L.P.C.