Browsing by Author "Gunasekaran, M."
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Item Additional fungi associated with leaf rot disease of coconut in India (a research note)(2007-02-08) Srinivasan, N.; Gunasekaran, M.Item An appraisal of symptom expression in coconut due to leaf rot disease(2007-02-08) Srinivasan, N.; Gunasekaran, M.Item Appraisal of the distribution of coconut root wilt and heavy incidence of the disease in Cumbum Valley of Tamil Nadu(2007-02-08) Srinivasan, N.; Koshy, P.K.; Kamalakshi Amma, P.G.; Sasikala, M.; Gunasekaran, M.; Solomon, J.J.Item Coconut leaf rot disease complex - A review(2007-02-08) Srinivasan, N.; Gunasekaran, M.Occurrence of leaf rot disease (LRDC) of coconut is related to increased incidence of root wilt disease (RWD). The palms with RWD irrespective of age are susceptible, young ones are more susceptible to LRDC. Tender leaves especially the spindle play a critical role in LRDC incidence and the disease attributed to fungal complex. Among the 14 species of LRDC fungi, several were proved to be pathogenic; Colletotrichum gloeosporioides (Penzig) Penzig and Sacc and Exserohilum rostratum (Drechsler) Leonard and Suggs are discerned as the main pathogens. C. gloesporoides was aggressive during monsoons and positively correlated with rainfall and relative humidity (% RH, whereas E.rostratum less strongly correlated. Fusarium spp. predominated in dry seasons. Importance of microclimate, survival and quiescence of the pathogens are to be determined. Diagnosis of RWD by techniques such as PCR and understanding the molecular basis of vulnerability of palms to LRDC would help to initiate early control measures. Planting of RWD cum LRDC resistant/tolerant varieties after eradicating the RWD infected palms is desirable. Protection of young leaves by chemical or biocontrol agents or a combination of both with phytosanitation is important. A system approach with integrated measures needs to be utilized for sound management of LRDC.Item Coconut leaf rot intensity and fungal incidence(2007-02-08) Srinivasan, N.; Gunasekaran, M.Item Coconut root wilt - The malady and remedy(2007-02-08) Solomon, J.J.; Nair, C.P.R.; Srinivasan, N.; Gunasekaran, M.; Sasikala, M.Item Crop Diseases: Identification and Management - A Colour handbook: Arecanut(CPCRI Kasaragod, 2000) Gunasekaran, M.; Chandra Mohanan, R.Item Crop Diseases: Identification and Management - A Colour handbook: Coconut(CPCRI, Kasaragod, 2000) Gunasekaran, M.; Chandra Mohanan, R.Item Curative and prophylactic control of fungal leaf rot complex in root (wilt) affected coconut palms in India(2003) Srinivasan, N.; Gunasekaran, M.Root wilt disease (RWD) is a debilitating malady of coconut in India that is caused by phytoplasma. In RIVD affedrd palms, leaf rot disease (LRD) is commonly superimposed. The LRD is due to fungi and this leaf rot phase forms an integral part of RIVD complex. Control of LRD is important as it severely disfigures the palm and brings about rapid deterioration in its health and productivity. Control trial involving Phytosanitation of young leaves, pouring of broad spectrum - systemic fungicide, Contaf 5 E (Uexaconazole 5% EC) into the axil of spindle leaf besides a number of other measures was conducted to study their ameliorating qffecf^nn LRD. Prophylactic control (rial, especially with the broad-spectrum fungicides was also conducted. Pouring of Contaf into the axil of spindles along with phytosanitory measures on the spindle and other young leaves significantly reduced the incidence, of LRD in newly emerging spindles effecting cure. Application of the fungicide on RIVD palms prior to the onset of LRD. offered prophylactic protection to emerging leaves against LRD. Relevance of practising integrated control measures, cure of LRD at an early stag< i''elf the need for strict adoption of crop management technology etc. for effective disease control are highlighted here.Item Cylindrocladium scoparium in relation to leaf rot disease of coconut(2007-02-08) Srinivasan, N.; Gunasekaran, M.Item Developing a polymerase chain reaction based detection method for coconut root (wilt) phytoplasma(2007) Mayilvaganan, M.; Gunasekaran, M.; Sheenakumari, T.K.; Geetha, L.; Rajeev, G.; Solomon, J.J.; Sasikala, M.Item Distribution and retention of oxytetracycline hydrochloride injected into coconut palms affected by root (wilt) disease(2007-02-08) Chowdappa, P.; Gopinathan Pillai, N.; Gunasekaran, M.; Solomon, J.J.Oxytetracycline-HCI (OTC) was administered by pressure injector into the trunks of root (wilt) diseased coconut palms. Uptake, translocation and persistence of OTC in various parts of the palms were monitored by microbiological assay of buffer extracts of fresh tissue samples using Bacillus cereus subsp. mycoides (ATCC 6462). Presence of OTC in the foliage was detected within 24 h after administration. The highest concentration was noticed after 5-6 days. Maximum detectable levels in the range of 3-11 Pg/g fresh weight were found in the leaf No. 11. Lower concentrations in the range of 1.0-5 Pg/g fresh weight were detected in the leaf No. 1, 6 and 31 after a week of injection. With the onset of senescence, OTC gets redistributed from older leaves to the most actively transpiring leaves. Very little OTC activity was detected in roots, inflorescence, and spear leaf. Detectable levels of OTC was observed for more than 12 weeks in the foliage.Item Emerging trends in the management of bud rot disease of coconut(2004-12) Gunasekaran, M.; Moosa, H.; Rasmi, A.R.; Rohini Iyer; Sheenakumari, T.K.In recent times there has been a resurgence of bud rot incidence more or less everywhere in the coconut-growing zones. Though application of Bordeaux mixture is very effective, there are practical difficulties in its implementation. Thesc reasons necessitate the formulation of an alternative IDM strategy for bud rot management. For bud rot management to be effective, a sound forecasting model(s) is an essential one. Considering this, attempts were made to develop forecasting models, based on macro and micro temperature, relative humidity (in plains and hilly areas), and rate of survival of the inoculum in endemic areas during off-season. As an alternative to Bordeaux mixture, systemic fungicides were evaluated: Aureofungin - sol (36.4 g I palm)followed by Calixin (21 ml I palm) as stem injection was found effective. The protection offered against bud rot pathogenby these systemic chemicals extended up to 8 weeks, thus safeguarding the palms during vulnerable period. No residues could be detected in nut water and kernal up to six months after application in the case of Calixin. Hence, the systemics can be administered in advance, well before the onset of the monsoon and there is no need-to climb the tree since the chemical can be administered from the ground. An endophytic bacterium (Bacillus amyloliqriefaciens), a fungus (Trichodernia harzianurn) and botanicals (Andrographispaniculata and Lawsonia inerntis) were found very effective against F palmivora. As these botanicals are not compatible with the antagonist, Z harzianurn sequential application of botanicals and Z har:ianlim by maintaining a suitable interval between the applications is suggested. With the use of standardized ex viva varietal screening technique, a tall cultivar, Laccadive Ordinary (LO) and a dwarf cultivar. Ganga Bondam (GB) were identified as bud rot tolerant varieties. Formulating an IDM strategy combining all the above practices, viz., planting resistant / tolerant varieties, bud rot forecasting based on weather parameters. application of systemic fungicides as prophylactic and application of antagonists (bacterium and fungus) and botanicals for long term sustenance of disease suppression is discussed in this paper.Item Etiology and recurrence of coconut leaf rot with special reference to seedlings(2007-02) Srinivasan, N.; Gunasekaran, M.A fungal complex causes leaf rot disease (LRD), Colletotrichum gloeosporioides and Exserohilum rostratum that superimposed on root wilt disease (RWD) affected coconut palms. Severe disease incidence was observed in young, field grown RWD affected seedlings. LRD was consistently reproduced in spindles of two year old RWD affected seedlings in field using the pathogens, individually and/or in combination. Pathogenic fungi produced lesions, subsequently resulted in rotting of the tissues. Lesions were observed on leaf petioles, mid-ribs/ veins, both in naturally infected and artificially inoculated plants. Spindles emerged subsequent to inoculation also exhibited disease symptoms indicating their recurrence. In artificially inoculated plants, £ rostratum produced lesions comparatively faster. From naturally LRD infected young palms, C. gloeosporioides, E. rostratum and some other fungi were isolated, confirming the complex fungal etiology of the disease. C. gloeosporioides was the most frequentlyItem Field control of leaf rot disease of coconut with fungicides(2007-02) Srinivasan, N.; Gunasekaran, M.Leaf rot is a disease of fungal complex super imposed on root (wilt) affected coconut palms in India. A field fungicidal control trial on the disease involving contact (indofil M-45, Fytolan) and systemic (Calixin) fungicides was conducted. Fungicidal treatments, spraying of Indofil M-45 and pouring of Calixin into axil of spindle, were found beneficial as the disease intensity reduced in newly emerged leaves. However, the extent of disease amelioration by fungicides was marginal to moderate level only. Importance of broad spectrum fungicide(s) and measures of disease protection are outlined.Item Fungi associated with leaf rot disease of coconut(2007-02) Srinivasan, N.; Gunasekaran, M.Studies on in vitro isolations of different fungi from leaf rot affected spindles showing early symptoms in a total of 300 palms revealed associa-tion of Colletotridmm gloeosporioides, Exserohilum rostratum, Gliocladium vermoeseni, Fuedrium solani, Fusarium monilifoTtne var. intermedium, Thielaviopsis paradoxa and cylmdrocladium scoparium with tissues of diseased spindles in differential frequencies. Independent recovery of C. gleosporioides,E. rostratum and I'usarium spp. (F. solani and F. monilifofme var. intermedium) from individual spots (leaf pieces) could bt: made in greater frequency. Isolations of fungi in various combinations was also obtained in different frequencies. The presence of only a single fungus or in combinations in individual palm is revealed. Association of more than one fungus with greater number of diseased palms has been brought out and can be attributed to the complex nature of the disease.Item Fusarium solani and Fusarium moniliforme in coconut leaf rot disease(2007-02) Srinivasan, N.; Gunasekaran, M.Item Identification of Colletotrichum Gloeosporioides, Exserohilum Rostratum and Gliocladium Vermoeseni Associated With Leaf Rot Disease of Coconut in India(2007-02) Srinivasan, N.; Gunasekaran, M.Leaf rot is a common disease predominantly superimposed on root (wilt) affected coconut palms in India. Three fungi implicated in the disease have been found to be Colletotrichum gloeosporioides, Exserohilum Yostratum and Gliocladium vermoeseni. The cultural characters and morphological features of these fungi have been described. The pathogenic role of these fungi has been confirmed. The three fungi independently induced symptoms leading to leaf rot. E. rostratum developed the disease symptom relatively faster. Pin prick injury in leaf pieces generally favoured the fungi in infection and had pronounced effect for G. vermoeseni.Item In Vitro Assay of Fungicides Against Preponderant Fungi of Leaf Rot Disease of Coconut Palms(2007-02) Srinivasan, N.; Gunasekaran, M.Efficacy of contact (Indofil M-45. Fytolan. Captaf. Thiride) and systemic (Contaf. Calixin. Aureofungin-sol with and without copper sulphate) fungicides in vitro was assessed against preponderant fungi (Colletotrichum gloeosporioides, Exserohilum rostratum, Gliodadium vermoeseni. Fusarium solani. F. moniliforme var. intermedium and Thielaviopsis paradoxa) of coconut leaf rot. Differential inhibition of fungi by fungicides was observed. Complete inhibition of ail fungi except F. moniliforme var. intermedium by Contaf was recorded at 0.1 5%. Indofil M-45/Calixin. Thiride were next in the order of efficacy. Usefulness of fungicides with broad spectrum activity/eradication potential in leaf rot control is stressed.Item In vitro biocontrol of coconut leaf rot pathogens with Pseudomonas fluorescens(Indian Society for Plantation Crops, 2003) Gunasekaran, M.; Alka Gupta; Srinivasan, N.