Browsing by Author "Sally K Mathew"

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Anthracnose disease of vegetable cowpea [Vigna unguiculata subsp. sesquipedalis (L.) verdcourt]
(Department of Plant Pathology, College of Horticulture, Vellanikkara, 1999) Praveen Kumar, M; Sally K Mathew
Bacterial wilt of pumpkin (Cucurbita Moschata Poir) and snakegourd (Trichosanthes Anguina L.) incited by pseudomonas solanacearvm (Smith) smith from India
(Kerala Agricultural University, 1994) Sally K Mathew; Beena Baby, S; Lissy Markose; Koshy Abraham
Characterisation and management of bitter gourd distortion mosaic virus
(Department of Plant Pathology, College of Horticulture, Vellanikkara, 2006) Reeny Mary Zacharia; Sally K Mathew
Studies on ‘Characterisation and management of bitter gourd distortion mosaic virus (BGDMV)’ conducted at College of Horticulture, Vellanikkara and Sugarcane Research Station, Thiruvalla during 1999-2004 dealt with various aspects especially on transmission, etiology, characterisation, identification of virus and management. Transmission studies proved that BGDMV was not transmitted through sap and seed. Germination percentage of seeds from infected plants was 45 per cent whereas seeds from healthy plants showed 85 per cent germination. The seedlings raised from infected seeds were pale, lanky and non vigorous. Studies on insect transmission revealed that whitefly, Bemisia tabaci Genn. was the vector of BGDMV. Minimum acquisition and inoculation feeding period for B. tabaci for transmission of BGDMV were found to be 15 min. Under natural conditions, common symptoms observed were light green and dark green mosaic patterns, curling, crinkling and distortion of leaves, reduction in number of flowers and fruits and reduction in size of fruits. Under artificial inoculation, symptoms initiated as light green and dark green mosaic patches in inoculated leaves, which later spread to young leaves and resulted in brittleness, pointed leaf lobes and crinkling. Average incubation period of BGDMV in bitter gourd plant was 14 days and the incubation period was found to decrease with increase in acquisition feeding period, inoculation feeding period and increase in number of viruliferous insects. A single viruliferous whitefly was capable of transmission upto 33 per cent and cent per cent transmission was obtained with increase in number of whiteflies to 10. Host range studies revealed that ash gourd, bottle gourd, coccinia, cucumber, pumpkin, snake gourd and water melon were not collateral hosts for the perpetuation of the virus. Purified preparations of BGDMV gave a characteristic ultraviolet absorption spectra of nucleoprotein with a peak at 241 nm. Average A260/A280 value of purified preparation of BGDMV was 1.62 and average concentration of the virus was 0.132 mg ml-1/100 g plant tissue. Characterisation of nucleic acid and viral proteins did not show any specific band of virus particles due to low concentration of particles in the purified preparation. Hence nucleic acid and protein coat could not be characterized. However SDS-PAGE of BGDMV infected field sample gave two additional bands at 16,419 and 24,970 D which could be proteins induced in host plant by virus infection. Electron microscopic observation of purified preparation of BGDMV gave monomers of size 18 nm diameter and geminate particles of size 18-20 x 30 nm. Infected samples from the field showed flexuous rod shaped particles of 750 nm resembling poty virus, in addition to geminate particles of size 18-20 x 30 nm, indicating a mixed infection of gemini and poty viruses. Immunosorbent electron microscopic observations using Indian cassava mosaic virus antiserum did not give a positive reaction, thus ruled out the relationship between BGDMV and Indian cassava mosaic virus. Serological tests using DAC-ELISA with 10-1 dilution of BGDMV showed that the virus was closely related to squash leaf curl virus. Based on transmission, electron microscopy and serological studies it was proved that the causal agent of bitter gourd distortion mosaic disease is a virus belonging to genus Begomo virus of family Geminiviridae. In the management studies, it was found that none of the treatments was found effective in preventing BGDMV infection. Disease incidence and severity and coefficient of infection showed a progressive trend with growth of the plant. Considering the overall performance of various treatments during the two seasons, it was found that treatment of imidacloprid 0.025 per cent was very effective in reducing disease incidence, disease severity and coefficient of infection. In the present study, application of coconut vinegar one per cent was also found to be effective in reducing disease incidence and severity of BGDMV. In the present study also treatment with Apis melliphica 30 potency and Arsenicum album 30 potency showed reduction in BGDMV and also increase in yield. During the second season, all the treatments were effective in reducing whitefly population than control. Studies on weather parameters showed that influence of mean maximum temperature, mean relative humidity on disease incidence varied with two seasons. Relative humidity in the forenoon showed positive correlation with disease incidence and disease severity in both seasons, and hence found to be the most influencing weather parameter in BGDMV infection.
Characterisation and management of tomato leaf curl virus in Kerala
(Department of Plant Pathology, College of Horticulture, Vellanikkara, 2014) Arun Paul; Sally K Mathew
Combatibility of certain fungicides and insecticides used for the control of major diseases and insect pests infesting the rice crop
(Department of Plant Pathology, College of Horticulture, Vellanikkara, 1992) Kalpana, T A; Sally K Mathew
Compatibility of certain fungicides and insecticides used for the control of major diseases and insect pests infesting the rice crop
(Department of Plant Pathology, College of Horticulture, Vellanikkara, 1992) Kalpana, T A; Sally K Mathew
Cylindrocladium leaf blight of Acacia auriculjformis A. cunn
(Kerala Agricultural University, 1996) Koshy Abraham; Beena, S; Anitha Cherian, K; Sally K Mathew
Efficacy of ligno-phenolic compost in the suppression of soil borne plant pathogens
(Department of plant pathology, College of horticulture, Vellanikkara, 2015) Gleena Mary, C F; Sally K Mathew
Enhancement of resistance to bacterial wilt in tomato by endophytic microbial communities
(Department of Plant Pathology, College of Horticulture, Vellanikkara, 2015) Deepa James; Sally K Mathew
The study on “Enhancement of resistance to bacterial wilt in tomato by endophytic microbial communities” was conducted in the Department of Plant Pathology, Department of Agricultural Microbiology, and Centre for Plant Biotechnology and Molecular Biology, College of Horticulture, Vellanikkara during the period 2011-2014. The endophytes were isolated from root and stem of healthy tomato plants from 16 locations of north, central and south Kerala. Endophytic microbial population varied with the plant samples and the population was more in root than stem. Bacterial population was higher than fungi and actinomycetes in root and stem. Among 154 endophytes isolated, 12 out of 79 bacteria, 16 out of 68 fungi, and four out of seven actinomycetes were antagonistic to R. solanacearum in in vitro. Among them, five bacteria, eight fungi, and two actinomycetes were promising in planta. Mutually compatible endophytic isolates were selected for the development of consortia and these were identified based on cultural, morphological and molecular characters. Of the five consortia tested, the one consisted of Trichoderma viride-1, T. viride-2, T. harzianum-1, Bacillus subtilis, and Streptomyces thermodiastaticus showed effect in reducing wilt incidence. Comparative study of the microbial consortium with individual endophytes showed the higher efficacy of consortium in reducing the wilt incidence. The endophytes were reisolated from soil, root, and stem of tomato plants. In pot culture experiment, the consortium applied as seed treatment + seedling dip + soil application at 45 DAP showed the minimum wilt incidence. Studies on the mechanism of antagonism of endophytic isolates showed, positive reaction towards ammonia and negative for HCN and siderophore production. The volatile and nonvolatile metabolites of the endophytes inhibited the pathogen. The endophytes showed varying levels of IAA and salicylic acid production with the maximum in T. harzianum-1 and B. subtilis respectively. Study on the effect of secondary metabolites of endophytes on the disease indicated that, seedlings dipped first in culture filtrate for 2 h and later dipped in bacterial inoculum for 30 min before planting showed the lowest per cent wilt incidence with the minimum for T. viride-2. Induction of systemic resistance was studied by assay of defense related compounds such as phenols, oxidative enzymes and PR proteins. The plants treated with microbial consortium showed higher activity of the defense related compounds with the maximum in plants inoculated with both consortium and pathogen. Field evaluation of endophytic consortium against bacterial wilt showed reduction in wilt incidence of 40.85 per cent in highly susceptible variety, PKM-1, 46.94 per cent in susceptible F1 hybrid, COTH-3, and 52.81 per cent in moderately resistant variety, Mukthi. Thus, the study revealed that, the application of endophytic consortium can enhance the resistance mechanism in tomato against bacterial wilt pathogen, R. solanacearum.
Etiology and management of damping-off of solanaceous vegetables
(Department of Plant Pathology, College of Horticulture, Vellanikkara, 1996) Bindu Menon; Sally K Mathew
Evaluation of selected varieties of okra for yield and resistance to yellow vein mosaic
(Kerala Agricultural University, 1993) Sally K Mathew; Abdul Vahab, M; Devadas, V S; Anitha Cherian
Seven selected varieties of okra were evaluated foryield and YVMV disease resistance under field conditions for three years at the Department of Olericulture, College of Horticulture, Vellanikkara, Trichur. Considering yield and disease resistance, the performances of the varieties Selection-4 and Arka Anamika were promising.
Management of bacterial wilt of solanaceous vegetabbles using microbial antagonists
(Department of Plant Pathology, College of Horticulture,Vellanikkara, 2003) Manimala, R; Sally K Mathew
Studies on 'Management of bacterial wilt of solanaceous vegetables using microbial antagonists' was conducted at the College of Horticulture, Vellanikkara during 2000- 2002. The major objective was to find out effective microbial antagonists against bacterial wilt ofbrinjal, chilli and tomato. Estimation of population of R. solanacearum showed the maximum in Vellanikkara than Ozhalapathy. The total rnicroflora was higher in Ozhalapathy than Vellanikkara and resistant varieties of the three crops recorded better association of microflora than susceptible ones. In in vitro evaluation , rhizosphere organisms isolated from the low wilt incidence area (Ozhalapathy) exhibited better antagonism against R. solanacearttm than those isolated from Vellanikkara. Among them, fungi were more effective than bacterial and actinomycete antagonists. The major fungal antagonists belonged to Trichoderma spp. and Aspergillus spp. T. viride (Ozhalapathy), T. pseudokoningii (forest soil) and Aspergillus niger (Eruthyampathy) were the most effective ones against R. solanacearum. Among the bacterial antagonists, P. aeruginosa and B. subtilis (Vellanikkara) were promising one. All commercial antagonists viz. T. viride, A. niger (Varanasi), A. niger (AN 27) T. harziamtm, B. subtilis and P. fluorescens were also effective against R. solanaeearum. Of the culture filtrates tested, T. virens and.E. subtilis (commercial) showed the maximum inhibition of the pathogen. The antagonists which were found most effective in laboratory condition performed well in pot culture studies also. Among the different methods of application of antagonists adopted, either seed treatment + soil drenching or root dipping were effective in reducing the wilt incidence and in delaying the wilt appearance. Use of antagonists in highly susceptible varieties did not give a promising control of bacterial wilt under field condition. In field trial, using a moderately resistant variety Mukthi, antagonists showed some effect in controlling bacterial wilt indicating that, an integrated effect by combined use of host resistance and microbial antagonists can provide a better control of bacterial wilt pathogen in the field.
Molecular cloning and characterization of the gene encoding B-1, 3 - glucanase in Trichoderma spp.
(Centre for Plant Biotechnology and Molecular Biology, College of Horticulture, Vellanikkara, 2008) Niharika Nath; Sally K Mathew
β–1,3–glucanase enzyme is widely distributed among bacteria, fungi and higher plants. Fungal β–1,3–glucanase produced by Trichoderma spp. is the key enzyme in the lysis of cell wall during their mycoparasitic action against several phytopathogenic fungi. This creates the potentiality of Trichoderma to be used as biocontrol agent. Biochemical characterization of the enzyme β–1,3–glucanase from different Trichoderma spp. has been reported. The gene encoding β–1,3–glucanase has been cloned and sequenced in several plants, bacteria and fungi. The study entitled “Molecular cloning and characterization of the gene encoding -1,3-glucanase in Trichoderma spp.” was carried out at the Centre for Plant Biotechnology and Molecular Biology (CPBMB) and Department of Plant Pathology, College of Horticulture, Vellanikkara during the period from 2006 to 2008. In the present study an attempt was made to determine the glucanase activity and to characterize β–1,3–glucanase gene of Trichoderma spp. Fifteen Trichoderma isolates, antagonistic to Phytophthora capsici, P. meadii, Pythium aphanidermatum and Ralstonia solanacearum were used for the present study. The enzyme activities of different isolates were found to be ranged from 1.3 U to 205.3 U per 50 ml culture filtrate for 10 min incubation. Among the fifteen isolates, the highest enzyme activity was found in T. viride–1 (205.3U) followed by T. harzianum-30 (157.8U), T. aureoviride (139.2U), T. viride-8 (121.9U) and these four were selected for gene isolation. The informations on glucanase gene sequences of different species of Trichoderma available in the public domain NCBI were collected and subjected to multiple sequence alignment to detect conserved boxes of the gene among species. Based on the data, three pairs of gene specific primer were designed for amplification of β–1,3–glucanase gene fragment of about 500 - 1400bp in Trichoderma spp. Genomic DNA was isolated from the four selected Trichoderma isolates. Amplification was obtained from two isolates by the primer combination of Glucan F1R1 and Glucan F2R2, whereas by Glucan F1R2, the amplification was obtained in all isolates. The amplicons obtained by Glucan F1R1 from T. aureoviride, by Glucan F2R2 from T. aureoviride and T. viride-8, by Glucan F1R2 from T. viride-1 and T. harzianum-30, were used for cloning. The amplicons were eluted, cloned in pGEM-T Easy Vector and transformed into E. coli JM 109 competent cells. High level of recombination was observed on blue-white screening. Recombination of the insert was confirmed by PCR of the plasmid, isolated from white colonies. The cloned fragments were sequenced to obtain the nucleotide sequence information. The sequences obtained after vector screening were named as GT-311, GT-322, BPT-822 and were subjected to Blast search. All the three sequences revealed significant levels of homology with glucanase genes of different Trichoderma spp. The sequences were also subjected to various theoretical sequence analysis using bioinformatics tools, which include ORF finder, GENSCAN, SOPMA, NEB cutter, Hydropathy plot, Interproscan, Motifscan, NASTATS and AASTATS tools of Biology Workbench. Sequences diversity of β–1,3–glucanase gene among different species of Trichoderma/Hypocrea was determined. The evolutionary distance of GT-322 from T. aureoviride and BPT-822 T. viride-8 was much lower and closely related to β-1,3-glucanase (glu) gene of T. viride having accession number EF176582.1. The two sequences cloned from T. aureoviride showed divergence, indicating the divergence of β–1,3–glucanase within the species. The sequence information obtained from the Trichoderma isolates during the present study can be further exploited for full length gene isolation to develop transgenic black pepper and ginger plants with resistance to Phytopthora capsici and Pythium aphanidermatum and can also be exploited to develop transgenic microorganism with high biocontrol potential.
New leaf spot disease in green amaranth
(Kerala Agricultural University, 2000) Krishnakumary, K; Sally K Mathew; Rajan, S
Phenotypic and molecular characterisation of phytophthora sp. inciting leaf fall of nutmeg
(Department of Plant Pathology, College of Horticulture, Vellanikkara, 2015) Sumbula, V; Sally K Mathew
Tuber rot of cassava (Manihot esculenta crantz) caused by geotrichum sp.
(Kerala Agricultural University, 1996) Sally K Mathew; Anitha Cherian, K; James Mathew
Varietal screening host range and control of downy mildew of bittergourd caused by rostow
(Department of Plant Pathology, College of Horticulture, Vellanikkara, 1996) Mini SImon; Sally K Mathew
A study was conducted at the College of Horticulture, Vellanikkara, during 1993-95, on varietal screening, host range and control of downy mildew of bittergourd (Pseudoperonospora cubensis (Berk. & Curt.) Rostow). Varieties obtained from the Department of Olericulture were screened for disease resistance and it was found that all the varieties tested were moderately susceptible to the disease. A preliminary screening of 174 genotypes of bittergourd available at NBPGR was conducted during August 1994 and all the genotypes were found to be infected. Only 32 genotypes were moderately resistant to the disease. Host range studies revealed that P. cubensis from bittergourd can infect other cucurbitaceous crops, such as bottlegourd, pumpkin, cucumber, snakegourd, ashgourd, watermelon and ivygourd. Four fungicides and four plant extracts were tested in in vitro, pot culture and field conditions to find out their effectiveness in reducing downy mildew infection. Among the fungicides, chlorothalonil (0.2%) was found to be the most effective as it gave maximum disease control, maximum yield and highest cost: benefit ratio. Among the botanicals, Ocimum leaf extract (10%) gave maximum reduction of the disease. In crop loss assessment, it was found that the highest CODEX of 60.22 per cent could cause an yield loss of 45.7 per cent under natural condition.
Witches' broom disease of Stachytarpheta indica Vahl.
(Kerala Agricultural University, 1987) Ravi, S; Sally K Mathew; Abi Cheeran