Rasmi, A.R.

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155Coconut, in spite of its hardy nature, is affectedby a number of diseases, which not only reduce yieldbut also kill the palms. Root (wilt), bud rot, basalstem rot, stem bleeding and grey leaf blight diseasesare the major diseases affecting coconut causingheavy losses in India. Grey leaf blight diseasecaused by Pestalotiopsis palmarum is of commonoccurrence in all coconut growing areas throughoutthe world. The disease causes serious damage innursery and in adult palms. The palms affected withgrey blight flowered relatively late than healthy ones(Abad et al., 1975). The leaf blight incidence reducethe coconut yield to the extent of 10-24 per cent(Karthikeyan and Bhaskaran, 1999)Adult coconut palms of 20-40 years of age werefound highly susceptible to the leaf blight disease.The disease symptoms appear first as minute yellowspots with a grey brown margin on the outer whorlof leaves. The spots are oval in shape measuring1 to 5 cm long (Menon and Pandalai, 1958).Gradually, the centre of the spots becomes grayishwhite while the brown colour of the margin deepens.Many spots coalesce to form large irregular necroticpatches. In advanced stage of infection it gives ablighted appearance (Nambiar, 1994).Das and Mahanta (1985) reported the inhibitionof P. palmarum under in vitro and in vivo conditionsby spraying Carbendazim. Root feeding ofThiophanate-methyl or Carbendazim or Tridemorphat 2 per cent concentration reduced the severity ofleaf blight disease of coconut in the field andincreased nut yield. (Kathikeyan and Bhaskaran,1998). Khalequzzaman et al. (1998) reported thatCarbendazim (0.1%) was effective fungicide againstgrey leaf spot pathogen.However, continuous use of specific systemicfungicides is not recommended, because, it has beenfound that systemic fungicides, when incorporatedinto the plant through stem and root, can leaveresidues in copra, nut-water and oil and also therecould be the danger of pathogen acquiring resistanceagainst these chemicals. Under these circumstances,environment friendly and less expensive methodslike the use of plant extracts have great relevance.This led to the present investigation of screeningplants for antifungal activity against P. palmarumcausing grey leaf blight disease of coconut with theultimate aim of developing an eco-friendlyformulation for disease management.The aqueous extracts of 10 plants were testedfor their antifungal property against P. palmarumby poison food technique (Bhaskaran et al., 1988).Fresh plant parts were collected and washed withtap water followed by sterile water. The plant partsselected were mainly leaves except Allium sativum,in which bulbs were selected.  Plant parts (100 g)were extracted with 100 mL of water and filteredthrough double layer of muslin cloth. PDA mediumwas amended with 10 per cent concentration of plantextracts and autoclaved for 20 minutes (Bhaskaranet al., 1988). Mycelial discs of 5 mm diameter fromthree day old cultures of P. palmarum were centrallyinoculated on the poured media in 90 mm petriplates. P. palmarum was isolated from leaf blightleaves collected from Vadakarapathy panchayath ofPalakkad district. Radial growth of the fungus wasJournal of Plantation Crops, 2015, 43(2):155-157Short Scientific ReportAntifungal activity of plant extracts against Pestalotiopsispalmarum causing leaf blight disease of coconutA.R. Rasmi*Post Graduate and Research Department of Botany, Govt. Victoria College, Palakkad-678 001, Kerala, India(Manuscript Received:29-10-14, Revised:18-02-15, Accepted:22-05-15)Keywords : Coconut, leaf blight, Pestalotiopsis palmarum, plant extracts*Corresponding Author: rasmi_ar@yahoo.com156measured after 72 and 96 hours. Mycelial growthin media without plant extract was taken as control.The growth inhibition was calculated based on thegrowth in the control plate. The growth inhibitionwas determined by applying the formula ofSkidmore, (1976).C–C1  x 100  CWhere, ‘C’ is the growth of P. palmarum incontrol plate and ‘C1’ is the growth of P. palmarumin the medium with plant extracts.The plant extracts which were found to bemaximum inhibitory to the mycelial growth ofP. palmarum were selected to study their effect onsporulation. PDA plate amended with 2 and 5 per centplant extracts were used for this study. Sporulationwas determined by adding 10 mL sterile distilledwater to each seven days old culture in the mediumamended with plant extract and gently scraping themycelia with a sterile glass rod to dislodge thespores. The spore suspensions obtained werefiltered through sterile cheesecloth into a sterile 50mL beaker and homogenized by manual shaking.The number of spores was counted using ahaemocytometer. The sporulation present inhibitionwas calculated based on the sporulation in thecontrol plate (Nduagu et al., 2008).Out of the 10 plant extracts studied, extractsof Lawsonia inermis, Cinnamomum zeylanicum,Lantana camara and Calotropis  gigantea showedgreater inhibition compared to other plant extracts.At 10 per cent concentration, Lawsonia inermis,Cinnamomum zeylanicum and Lantana camarashowed 100 per cent inhibition after 72 and 96 hrs(Table 1). Calotropis  gigantea  leaf extract showed97.5 and 98.6 per cent inhibition after 72 and 96hrs respectively. This study showed that when theplant extracts of different concentrations were addedto medium, a reduction in the mycelial growth ofP. palmarum observed, however, the efficacy variedwith plant extracts and concentration.All the selected plant extracts showed reductionin the sporulation of P. palmarum. The highestinhibition of sporulation of P. palmarum wasrecorded in the case   of Cinnamomum and Lawsonia(Table 2). Cinnamomum exhibited 73.3 and 94.3per cent inhibition at 2 and 5 per cent concentrationrespectively. Lawsonia showed 75.8 and 97.0per cent inhibition at 2 and 5 per cent concentrationrespectively. The results obtained from differentstudies showed that the crude extracts of Lawsoniainermis, Cinnamomum zeylanicum, Lantanacamara and Calotropis  gigantea leaves exhibitedthe highest antifungal activities against P. palmarum.The inhibition was expressed as reduced radialgrowth and sporulation. Bhuvaneswari et al. (2010)Table 1. In vitro evaluation of different plant extracts on mycelial growth of P. palmarumPlant extracts Family Per cent inhibition after Mean72 hrs 96 hrsAllium sativum Linn. Amaryllidaceae 31.1(26.7) 35.3(33.3) 33.2(30.0)Azadirachta indica A. Juss. Meliaceae 29.5(24.2) 35.8(34.2) 32.7(29.2)Calotropis gigantean R.Br. Asclepiadaceae 75.0(93.3) 76.4(94.5) 75.7(93.9)Cinnamomum zeylanicum Blume. Lauraceae 76.4(94.5) 78.5(96.0) 77.4(95.3)Lantana camara  Linn. Verbanaceae 75.8(94.0) 78.1(95.8) 77.0(94.9)Lawsonia inermis Linn. Lythraceae 78.1(95.8) 79.4(96.6) 78.8(96.2)Murraya koenigi  Spr. Rutaceae 28.9(23.3) 32.0(32.1) 31.8(27.7)Nerium odorum Linn. Apocynaceae 33.5(30.5) 40.8(42.7) 37.2(36.6)Ocimum sanctum Linn. Lamiaceae 31.1(26.8) 28.2(22.3) 29.7(24.6)Piper nigrum Linn. Piperaceae 36.0(34.5) 37.3(36.8) 36.7(35.7)C.V. % = 6.3CD (P= 0.05) for plant extracts = 1.8CD (P= 0.05) for time intervals = 0.4CD (P= 0.05) for plant extracts x time intervals = 2.6Transformation used: sin-1 “ p, where ‘p’ is the inhibition per centRasmi157reported the mycelia inhibitory activity byCinnamomum  zeylanicum and Lawsonia  inermison P. palmarum causing leaf blight in palmyarh.Rasmi  and Rohini Iyer (2010) reported  theantifungal properties of Andrographis paniculataand  Lawsonia inermis against P. palmivora, causingbud rot disease in coconut.Present study shows that the  extracts ofLawsonia inermis,  Cinnamomum zeylanicum,  andLantana camara, which showed inhibitory  effecton P. palmarum  can be utilized as new componentof Integrated Disease Management (IDM) packagefor controlling grey leaf blight disease of coconut.Further studies on in vivo efficacy of thesebotanicals and identification of fungitoxic principlesneeds to be ascertained which will be useful for theformulation of safer and more economical pesticides.ReferencesAbad, R.G., Prudente, R.L. and Magat, S.S. 1975. Incidenceof leaf spot in coconut fertilized with variouscombinations of nitrogen, phosphorus and potassiumchloride. In: Proceedings of 6th Annual ScientificMeeting, Crop Science Society. Bacold City. pp. 31-32.Bhaskaran, R., Ramadass, N. and Ramachandran, T.K. 1988.Biological control of Thanjavur wilt disease of coconut.Indian Coconut Journal 19(6): 3-8.Das, C.M. and Mahantha, I.C. 1985. Evaluation of somefungicides against Pestalotiopsis palmarum incidence ofgrey blight of coconut. Pesticides 19: 37-39.Karthikeyan, A. and Bhaskaran, R. 1998. Evaluation offungicides in the control of leaf blight disease of coconutcaused by Pestalotiopsis palmarum (Cooke) Stey. IndianCoconut Journal 29(9): 6-7.Karthikeyan, A. and Bhaskaran, R. 1999. Incidence of leafblight disease in relation to age, vigour of coconutseedlings and yield of palms. Madras AgriculturalJournal 86: 80-82.Khalequzzaman, K.M., Hossain, I. and Hossain, M.M.  1988.Effect   of fungicides and potash in controlling grey leafspot disease of coconut. Bangladesh Journal of Trainingand Development 11: 151-156.Menon, K.P.V. and Pandalai, K.M 1958. The Coconut Palm-A Monograph. Indian Central Coconut Committee,Ernakulam, 384 p.Nambiar, K.K.N. 1994. Diseases and  disorders of coconut.In: Advances in Horticulture. Vol. X – Plantation andSpice Crops. Part-1. (Eds) Chadha, K.L and Rethinam,P. Malhotra Publishing House, New Delhi. pp. 857-882.Nduagu, C.,  Ekefan, E.J. and Nwankiti, A.O. 2008. Effect ofsome crude plant extracts on growth of Colletotrichumcapsici (Synd.) Butler & Bisby, causal agent of pepperanthracnose. Journal of Applied Biosciences 6(2): 184-190.Rasmi, A.R. and Rohini Iyer, R. 2010. Effect of plant extractson Phytophthora palmivora causing bud rot disease ofcoconut. Journal of Plantation Crops 38(3): 231-234.Skidmore, A.M. 1976.  Interactions in relation to biologicalcontrol of plant pathogens. In: Microbiology of AerialPlant Surface. (Eds.) Dickson, C.H. and Prece, T.E.Academic Press, London. pp. 507-528.Bhyvaneswari, V., Venkata Ramana, K.T., Bhagavan, B.V.K.,Naga Lakshmi, R. and Srinivasalu, B. 2010. In vitrostudies on management of leaf blight disease of palmyrahcaused by Pestalotiopsis palmarum (Cooke) Stey.Journal of Plantation Crops 38(2): 165-167.Table 2. Inhibition of sporulation of  P. palmarum by plant extractsPlant extracts Per cent inhibition of sporulationin concentrations Mean(2%) (5%)Calotropis gigantea R.Br. 54.7(66.6) 67.6(85.5) 60.7(76.0)Cinnamomum zeylanicum Blume. 58.9(73. 3) 76.2(94.3) 66.3(83.8)Lantana camara  Linn. 54.0(65.5) 68.2(86.3) 66.6(75.9)Lawsonia inermis  Linn. 60.4(75.8) 79.9(96.9) 68.3(86.4)C.V. % = 5.3CD (P= 0.05) for plant extracts = 1.8CD (P= 0.05) for concentrations = 0.7Transformation used: sin-1 “ p,  where ‘p’ is the inhibition per centPlant extracts against Pestalotiopsis in coconut

Antifungal activity of plant extracts against Pestalotiopsis palmarum causing leaf blight disease of coconut

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Antifungal activity of plant extracts against Pestalotiopsis palmarum causing leaf blight disease of coconut

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