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Kerala Agricultural University, Thrissur
The history of agricultural education in Kerala can be traced back to the year 1896 when a scheme was evolved in the erstwhile Travancore State to train a few young men in scientific agriculture at the Demonstration Farm, Karamana, Thiruvananthapuram, presently, the Cropping Systems Research Centre under Kerala Agricultural University. Agriculture was introduced as an optional subject in the middle school classes in the State in 1922 when an Agricultural Middle School was started at Aluva, Ernakulam District. The popularity and usefulness of this school led to the starting of similar institutions at Kottarakkara and Konni in 1928 and 1931 respectively.
Agriculture was later introduced as an optional subject for Intermediate Course in 1953. In 1955, the erstwhile Government of Travancore-Cochin started the Agricultural College and Research Institute at Vellayani, Thiruvananthapuram and the College of Veterinary and Animal Sciences at Mannuthy, Thrissur for imparting higher education in agricultural and veterinary sciences, respectively. These institutions were brought under the direct administrative control of the Department of Agriculture and the Department of Animal Husbandry, respectively. With the formation of Kerala State in 1956, these two colleges were affiliated to the University of Kerala. The post-graduate programmes leading to M.Sc. (Ag), M.V.Sc. and Ph.D. degrees were started in 1961, 1962 and 1965 respectively.
On the recommendation of the Second National Education Commission (1964-66) headed by Dr. D.S. Kothari, the then Chairman of the University Grants Commission, one Agricultural University in each State was established. The State Agricultural Universities (SAUs) were established in India as an integral part of the National Agricultural Research System to give the much needed impetus to Agriculture Education and Research in the Country. As a result the Kerala Agricultural University (KAU) was established on 24th February 1971 by virtue of the Act 33 of 1971 and started functioning on 1st February 1972. The Kerala Agricultural University is the 15th in the series of the SAUs.
In accordance with the provisions of KAU Act of 1971, the Agricultural College and Research Institute at Vellayani, and the College of Veterinary and Animal Sciences, Mannuthy, were brought under the Kerala Agricultural University. In addition, twenty one agricultural and animal husbandry research stations were also transferred to the KAU for taking up research and extension programmes on various crops, animals, birds, etc.
During 2011, Kerala Agricultural University was trifurcated into Kerala Veterinary and Animal Sciences University (KVASU), Kerala University of Fisheries and Ocean Studies (KUFOS) and Kerala Agricultural University (KAU).
Now the University has seven colleges (four Agriculture, one Agricultural Engineering, one Forestry, one Co-operation Banking & Management), six RARSs, seven KVKs, 15 Research Stations and 16 Research and Extension Units under the faculties of Agriculture, Agricultural Engineering and Forestry. In addition, one Academy on Climate Change Adaptation and one Institute of Agricultural Technology offering M.Sc. (Integrated) Climate Change Adaptation and Diploma in Agricultural Sciences respectively are also functioning in Kerala Agricultural University.
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ThesisItem Open Access Management of bitter gourd mosaic by enhancing host resistance(Department of Plant Pathology, College of Horticulture, Vellanikkara, 2015) Ashwini, K N; KAU; Vimi, LouisBitter gourd (Momordica charantia L.) is one of the important vegetable crops that occupy a pivotal position among fruit vegetables, particularly in south India. The fruits of this crop which have high commercial value and are being used for culinary preparations and various medicinal preparations. In spite of the economic importance of this vegetable, the research work carried out on protection of crop from viral disease is quite scanty. In many case, cent per cent mosaic incidence was recorded in the crop resulting in substantial economic loss. So the present study was focused on screening of bitter gourd accessions and management of bitter gourd mosaic by enhancing host resistance using defense inducers. The three different viruses causing mosaic in bitter gourd are cucumber mosaic virus (CMV), potyvirus and bitter gourd distortion mosaic virus (BDMV). As these viruses causes mixed infection in field, the separation of individual viruses was carried out using systemic indicator host plants. For separation of CMV and potyvirus, systemic indicator host plants used were cosmos and papaya respectively. BDMV was separated by white fly transmission. The pure cultures of viruses were maintained on the susceptible bitter gourd variety Preethi. The symptoms developed by different viruses were recorded under natural and artificial conditions were recorded CMV produced mosaic specks, yellow-green mosaic patches, leathery leaves and downward rolling of leaf margin. Symptoms of potyvirus infection were vein clearing, puckering, malformed leaf with reduced leaf size and rugosity. BDMV infection produced mosaic, puckering, leaf distortion, hairy growth on leaves and vines with reduction in leaf size and internodal length. For the screening of bitter gourd accessions against CMV and potyvirus, potassium phosphate buffer pH 7.0 was found to be the most suitable buffer. Among 22 accessions screened, three accessions viz., TCR 285, TCR 39 and TCR 53 were highly resistant to CMV; one accession Biliagala was highly resistant to potyvirus and 11 accessions viz.,TCR 285, TCR 39, TCR 493 ,TCR 416, TCR 492, TCR 494,TCR 380, TCR 202 and TCR 149, Green long and Biliagala were highly resistant to BDMV. The field experiment was undertaken with the objective of management of bitter gourd mosaic by using defense inducers. The three different defense inducers viz., salicylic acid 25 ppm, barium chloride 0.1% and Pseudomonas fluorescens 2 % were evaluated on the moderately resistant cultivar white long and susceptible variety Preethi. The mosaic symptom was recorded after 51 days of sowing in salicylic acid treated plants and after 40 days of sowing in control. A time gap of 5-10 days after spray of defense inducer was required for development of resistance in plants. The lowest disease severity was observed in cultivar White long treated with salicylic acid. The highest yield was recorded in Preethi treated with Pseudomonas fluorescens.ThesisItem Open Access Anthracnose disease of vegetable cowpea [Vigna unguiculata subsp. sesquipedalis (L.) verdcourt](Department of Plant Pathology, College of Horticulture, Vellanikkara, 1999) Praveen Kumar, M; KAU; Sally Mathew, KA study on vanous aspects of anthracnose disease of cowpea was conducted at College of Horticulture, Vellanikkara during 1997-98. Etiological studies revealed Colletotrichum lindemuthianum (Sacc. and Magn.) Br. and Cav. as the main pathogen causing anthracnose disease in Kerala and the pathogen was found to be seed borne. Among the 50 genotypes tested, Kanakamony was found immune to the disease and seven genotypes were highly resistant to the disease. In ( disease management studies, all fungicides, botanicals and antagonist Trichoderma viride were equally effective under in vitro and field conditions. As far as disease control, yield and C:B ratio were concerned, mancozeb was found to be the best treatment. Summer season was found to be the best season for cowpea cultivation in areas where anthracnose is a problem. In crop loss assessment, significant difference was noticed between carbendazim treated and untreated plots in case of disease infection and yield, and yield loss of 53.85 per cent was recorded under natural condition due to this-disease.ThesisItem Open Access Biocontrol of rhizome rot of ginger using selected antagonists(Department of Plant Pathology, College of Horticulture, Vellanikkara, 1999) Julie George, K; KAU; Sukumaravarma, MRhizome rot of ginger cas used by Pythium aphantdermatum (Edson) Fitzpatrick is one of the most destructive diseases of ginger in Kerala. The pathogen was isolated and its pathogenecity was established by Koch's postulates in ginger variety Rio-de-Jenerio. Among the various food bases evaluated, for the mass multiplication of selected antagonists, rice hull was found to be significantly superior to all others to obtain maximum growth for Trichoderma viride and Aspergillus flavus. For Aspergillus niger, rice bran was found to be significantly superior. The results on the effect of various treatments on germination showed that there was no significant difference among the treatments. The effect of antagonists on the pre- emergence rotting and post-emergence rotting (rhizome rot) were studied. In plots where antagonists (T viride, Aflavus or A. niger) or fungicides (mancozeb or copper oxychloride) were applied either as seed treatment or as soil incorporation at the time of planting, the pre-emergence rotting was not observed. The plot in which the antagonists T. vtride, A. mger and At flavus were applied in combination at 60 and 120 OAP, recorded the minimum rhizome rot incidence compared to other treatments. The plots in which the antagonists were applied twice, i.e., 60 and 120 OAP, the rhizome rot incidence was minimum compared to the plots with only one time application of antagonists. The maximum population of the pathogen P. aphanidermatum. was observed in plot where A. flavus was applied in combination with mancozeb. The multiplication of selected antagonists, 7: viride, A. flavus and A. niger in soil was found out by estimating their population at different stages. The population of T. virtde was maximum in plots where it was applied in combination with mancozeb in most of the period. The soil application of the combination of antagonists T. viride, A. flavus and A. niger did not affect the multiplication of anyone of them in soil. In general, soil incorporation of antagonists was found to helping in their mulitplication profusely compared to the seed treatment. The incorporation of the antagonists A. flavus and A. niger to the plots, twice was found to be superior than applying them only once, for getting maximum multiplication of propagules in soil. The result on the compatibility of antagonist with fungicide in field condition revealed that the antagonist T viride was quite compatible with mancozeb whereas A. flavus and A. niger were compatible with both fungicides tested (mancozeb and copper oxychloride). The treatments which was found to be superior in minimising the incidence of rhizome rot of ginger viz., T 16 (soil incorporation of T vir/de, A. niger at 60 and 120 DAP) and TI9 (soil incorporation of I: viride, A. niger and A. flavus) also recorded the maximum yield of ginger.ThesisItem Open Access Host range studies and management of anthracnose of nutmeg caused by colletotrichum spp.(Department of Plant Pathology, College of Agriculture, Vellayani, 2020) Bommana, Divya; KAU; Heera, GThe study entitled “Host range studies and management of anthracnose of nutmeg caused by Colletotrichum spp .” was conducted at Department of Plant Pathology, College of Agriculture, Vellayani during 2018-2020 with the objectives to characterize the causal agent, study the host range of Colletotrichum spp. causing anthracnose and to develop effective management strategy to control the disease by using new generation fungicides. As a part of the study, anthracnose infected samples were collected from four nutmeg growing districts of Kerala viz., Thiruvananthapuram, Kottayam, Ernakulam and Idukki. For the infected sample collections, three locations from Thiruvananthapuram (Vellayani, Karamana and Palode), two locations from Kottayam (Kumarakom and Vaikom), six locations from Idukki (Myladumpara, Pampadumpara, Adimali, Kambilikandam, Panickankudy and Kattapana) and one location from Ernakulam (Kadungalloor) were surveyed. Disease incidence and severity were assessed from the surveyed locations. The highest disease incidence and severity were observed in Kadungalloor (DI - 90 % and PDI - 56.40 respectively) followed by Kumarakom (DI - 80 % and PDI - 41.33 respectively) and the lowest disease incidence and severity in Myladumpara (DI - 20 % and PDI - 15.53 respectively). The symptoms of the anthracnose on nutmeg appeared as small necrotic spots with a prominent yellow halo on the leaf lamina. Several lesions coalesced together resulted in leaf blight, shot hole and defoliation. In Kambilikandam and Panickankudy. fruit rot was also observed along with leaf spot. The cultures of Colletotrichum spp. were isolated from the infected samples from different locations. Eighteen pure cultures of Colletotrichum sp. (C1 to C18) were obtained. Seven isolates of Colletotrichum sp. were selected for further studies based on the days taken for symptom development and rate of lesion development. The pathogenicity of the seven isolates of Colletotrichum sp. from different locations were proved by Koch postulates. The morphological and culture characters of the seven different isolates were studied in potato dextrose agar (PDA) medium. The isolated cultures of Colletotrichum sp. produced whitish to greyish radiating mycelium; later turning to off white to pink coloured fluffy to sparse mycelium with regular margins. Days taken to grow the entire Petri dish ranged from 7 to 10. The mycelium of the fungus was hyaline and septate; and its width ranged from 0.46 μm to 2.48 μm. The conidia were single celled with an oil globule at the centre and wereoblong or dumbbell shaped. The conidial size varied from 7.87 to 19.97 μm x 3.26 to 5.68 μm. The isolates were morphologically identified as C. gloeosporioides. The pathogenic variability of the seven isolates of C. gloeosporioides was assessed on detached nutmeg twigs by virulence rating. The isolate C4 was identified as the most virulent isolate which produced lesion size of 11.89 cm and 16.81cm at 7 DAI and 9 DAI respectively. The isolate C4 produced symptoms within two days after artificial inoculation and had a higher rate of lesion development of 4.12 cm day -1 . The other isolates took 3 to 4 days for symptom appearance on artificial inoculation of the pathogen. Host range of the most virulent isolate of C. gloeosporioides (C4) obtained from nutmeg was studied in perennial tree spices viz., clove, cinnamon, all spice, betel vine, black pepper and coconut. C. gloeosporioides isolate of nutmeg is capable of infecting the above- mentioned host plants. The isolate produced symptoms in all the hosts within 2 to 4 DAI and the symptoms developed varied from brown lesions, brown lesions with a shot hole to necrotic spots with prominent yellow halo. The maximum lesion size of 2.43 cm was observed in clove and minimum lesion size of 1.31 cm in all spice. In vitro screening of new generation fungicides revealed that triazole group fungicide propiconazole 25EC at 100 ppm and combination fungicides, carbendazim 12% + mancozeb 63% at 25 ppm; and Trifloxystrobin 25% + Tebuconazole 55% WP at 100 ppm concentration were the most effective in completely inhibiting the mycelial growth of the pathogen. The present study revealed the wide host range of the C. gloeosporioides isolate of nutmeg and also the effectiveness of new generation fungicides in managing the pathogen. The future line of work should include molecular variability between various isolates, cross infectivity among the isolates in other perennial hosts, and the efficacy of new generation fungicides under field condition.ThesisItem Open Access Varietal screening and management of anthracnose of black pepper using new generation fungicides(Department of Plant Pathology, College of Agriculture, Vellayani, 2020) Athira, K; KAU; Heera, GThe study entitled “Varietal screening and management of anthracnose of black pepper using new generation fungicides” was conducted at Department of Plant Pathology, College of Agriculture, Vellayani during 2018 - 2020 with the objective to screen KAU varieties and most popular local cultivar Karimunda for resistance against anthracnose of black pepper caused by Colletotrichum gloeosporioides (Penz.) Penz. and Sacc. and evolve management strategy using new generation fungicides. As a part of the study, diseased samples were collected from three black pepper growing tracts of Kerala viz., Thiruvananthapuram, Wayanad and Idukki. Sample collections were made from two locations from Thiruvananthapuram (Kowdiar and Vellayani), Wayanad (Meenangadi and Ambalavayal) and Idukki (Myladumpara, Pampadumpara, Kattapana and Kambilikandam). Disease incidence and severity were assessed from the surveyed locations. The highest percentage disease index was observed in Myladumpara (50.28%) followed by Kattapana (48.62%). Weather parameter viz., temperature, relative humidity and rainfall were recorded during the survey period. The weather parameters viz., low temperature, high relative humidity and heavy rainfall favoured the incidence of anthracnose. The symptoms of the anthracnose appeared as small necrotic spots with a yellow halo on the leaf lamina. Several lesions coalesce together resulted in leaf blight and defoliation. In Pampadumpara, spike infection was also observed along with leaf spot. Colletotrichum cultures were isolated from the diseased sample by tissue isolation technique and eight pure cultures of Colletotrichum sp. (C1 to C8) were obtained. The pathogenicity of the eight isolates of Colletotrichum sp. from different locations were proved by Koch postulates. The morphological characters of the eight different isolates were studied in potato dextrose agar (PDA) medium. The isolated cultures of Colletotrichum sp. produced whitish with yellowish orange centre to light pink, off white to greyish coloured colony having fluffy, cottony to sparse mycelial growth with regular margins. Days taken to grow the entire petridish ranged from 7.25 to 9.75 days. The mycelium of the fungus was hyaline and septate, and its width ranged from 2.21 - 3.45 μm. The septal distance of the different Colletotrichum isolates ranged between 8.50 - 21.23 μm. The conidia were single celled with an oil globule at the centre. The conidial shape was either cylindrical, oblong or dumbbell. The conidial and appressorial size varied from 9.4 - 12.1 μm x 3.6 - 4.6 μm and 8.5 – 11.2 μm x 3.5 – 4.3 μm respectively. The isolates were identified as Colletotrichum gloeosporioides. The pathogenic variability of the eight C. gloeosporioides isolates were assessed on three black pepper varieties viz., Panniyur 1, Panniyur 3 and Karimunda by virulence rating. The isolate C7 was identified as the most virulent isolate which produced lesion size of 1.92 cm, 2.40 cm, and 3.22 cm on Panniyur 1, Panniyur 3 and Karimunda respectively at 5 days after inoculation (DAI). The isolate C7 produced symptoms within two days after artificial inoculation in the three varieties tested with a higher rate of lesion development of 0.40 (Panniyur 1), 0.49 (Panniyur 3) and 0.66 (Karimunda) cm day-1. KAU varieties (Panniyur 1 to 8) and local cultivar Karimunda were screened against the most virulent isolate of C. gloeosporioides. Among the varieties screened, Panniyur 4 was found to be highly susceptible with highest PDI of 51.43 (7 DAI), whereas Panniyur 2 had the lowest PDI of 14.28 (7DAI) followed by Panniyur 8 with PDI 20.00 % (7DAI) and were found to be tolerant to anthracnose infection. Panniyur 1, Panniyur 7 and Panniyur 5 were also found to be moderately susceptible. The pathogen produced symptoms in susceptible varieties within 2 DAI, whereas the tolerant varieties took 3-4 days to initiate the infection. In vitro screening of new generation fungicides revealed that kresoxim methyl of strobilurin and tebuconazole of triazole were the most effective in inhibiting mycelial growth of C. gloeosporioides (80.37% and cent percent respectively). The combination fungicide carbendazim 12% + mancozeb 63 % completely inhibited the mycelial growth at 25, 50 and 100 ppm. The combination fungicides azoxystrobin 11% + tebuconazole 18.3% SC and trifloxystrobin 25% + tebuconazole 55% WP were also effective against the pathogen at 100 ppm. The contact fungicide copper oxychloride was ineffective against the pathogen @ 10, 25, 50 and 100 ppm. The present study revealed the use of tolerant varieties along with need based application of new generation fungicides to keep the destructive disease under control. The future line of work should include screening of more black pepper varieties under field condition to assess their reaction to anthracnose, elucidation of the factors governing resistance to the disease and the efficacy of new generation fungicides under field condition.ThesisItem Open Access Eco-friendly management of Fusarium rot in cardamom and its impact on soil health and plant defence mechanism(Department of Plant Pathology, College of Agriculture, Vellayani, 2020) Veni Krishna, K C; KAU; Dhanya, M KThe study entitled ‘Eco-friendly management of Fusarium rot in cardamom and its impact on soil health and plant defense mechanism’ was conducted at College of Agriculture, Vellayani and Cardamom Research Station Pampadumpara during 2018- 2020 with the objective to assess Fusarium rot severity and pathogen variability in Idukki district, develop an effective ecofriendly management practices for the disease and study the impact of the practices on the soil and plant health. Six isolates of Fusarium oxysporum Schlecht were obtained, three each from infected pseudostem and roots collected from Kattapana and Nedumkandam blocks of Idukki district. The isolate, Fp1 from pseudostem (Pampadumpara panchayath) was identified as most virulent based on virulence rating (viz., days taken for symptom development, lesion length, mycelial growth), and was used for further studies. Inoculation of the root isolate (Fr1) also produced typical lesion on pseudostem indicating that the, fungus can also attack pseudostem besides the roots. But the root isolate took more days (40 days) for symptom development compared to pseudostem isolate (29 days). The morphological characters including the colour, colony characters, hyphal and conidial characters as well as rate of growth in Petri dish confirmed the fungus as F. oxysporum. In vitro studies revealed that the isolates from pseudostem and roots showed significant variation in their morphological, cultural and pathological characters. A pot culture experiment was conducted to assess the efficacy of selected bioagents (individually and in combination) for the management of the disease at CRS Pampadumpara in CRD using nine treatments with three replications. Pathogen inoculum (150 gm/10 kg soil) multiplied in sand-maize flour medium was standardised as the inoculum level enough for cent per infection on the pseudostem resulting in complete crop loss. Soil application of vermiculite based AMF inoculum (20 g) with @ 2% Pseudomonas fluorescens (1 L/10 kg soil) per 10 kg soil at the time of planting along with 2% P fluorescens spray @ 0.5 L/ plant at monthly interval for three times resulted in effective disease management (disease incidence: 40% and disease severity: 24.26%) compared to the inoculated control (disease incidence: 100% and disease severity: 69.38 %). Studies on the population dynamics of the pathogen and the biocontrol agents at periodical interval upto three months revealed significant reduction in the pathogen antagonist ratio and enhancement in AMF colonization of the treatment plants. Among the best treatment the combination of AMF and P. fluorescens resulted in good biometric characters of the treatment plants (plant height: 96.50 cm ,leaf length: 62.50 cm and number of leaves: 15.75) compared to control (plant height: 41 cm ,leaf length: 30 cm and number of leaves: 7.50) through enhancement of soil nutrients (P, K, Ca and Mg) and plant nutrient status (K, Mg, S and B) compared to control plants. Laboratory studies also revealed the induction of defense related enzymes (phenol, ortho dihydroxy phenol, peroxidase, polyphenol oxidase, and β 1,3 glucanase) in high concentration as a response to the application of above treatments. Thus, the present study revealed that Fusarium rot of cardamom a devastating disease can be effectively managed by soil application of vermiculate based AMF inoculum (20 g) with 2 per cent P. fluorescens (1L/10 kg soil) per 10 kg soil at the time of planting along with 2 per cent P. fluorescens spray at 0.5 L per plant at monthly interval for three times; this treatment also resulted in good vegetative growth of cardamom plants therefore this can be used as an ecofriendly management strategy for the production of good quality cardamom.ThesisItem Open Access Strain improvement of Trichoderma spp. by protoplast fusion(Department of Plant Patholgy, College of Agriculture, Vellayani, 2020) Anit, Cyriac; KAU; Sible George, VargheseA study on “Strain improvement of Trichoderma spp. by protoplast fusion” was conducted at Department of Plant Pathology, College of Agriculture, Vellayani during the year 2018-2020, with the objective of improving the screened strains of Trichoderma spp. by protoplast fusion for spp. by protoplast fusion for increasing the antagonistic ability and related traits against soil borne pathogens. A survey was conducted in five agro-climatic zones of Kerala viz., Northern Zone, Central Zone, High Range Zone, Problem Area Zone and Southern Zone for collection of soil samples especially from forest soils. The collected soil samples were assessed for the population of Trichoderma spp. A total of 31 Trichoderma spp. isolates were obtained from the soil samples collected from five agro-climatic zones. Majority of the isolates were obtained from soils with pH of 6 to 7. Isolate TRMW2, TREN1, TREZ1, TREZ2, TREZ3, TRRN1, TRRN2, TRKR1, TRPN3, TRPN7, TRPN10 and TRPN18 exhibited full growth at four days after inoculation (DAI). The isolated Trichoderma spp. differed in growth rate and colony characters like colour of mycelium, texture of colony and sporulation pattern. Isolates of Trichoderma spp. from different zones exhibited in vitro inhibition against soil borne pathogens such as Pythium aphanidermatum and Rhizoctonia solani. Majority of the isolates displayed high inhibition per cent compared to KAU strain of Trichoderma sp. TRRN1, TRRN2, TRPN3, TRPN7, TRPN11, TRPN15 and TRKR2 isolates exhibited complete inhibition of P. aphanidermatum in dual culture experiment; whereas TREN1, TRMW2, TREZ1, TREZ2, TRKM1, TRPN7, TRPN9, TRPN14, TRPN15, TRPN17, TRPN18 and TRKR2 isolates exhibited complete inhibition of R. solani. Trichoderma isolates such as TRPN7, TRPN15 and TRKR2 exhibited complete inhibition against both the pathogens. Antagonistic properties viz., antibiosis, lysis and overgrowth of Trichoderma isolates against P. aphanidermatum and R. solani were observed. During the antagonist-pathogen interaction, isolates TRSN1, TRSN2, TRPN10, TRPN14, TRPN15, TRPN17 and TRPN18 exhibited high levels of antibiosis. Most of the isolates caused lysis of mycelium of the pathogens which resulted in formation of clear zones in dual culture. Overgrowth of the antagonist was another prominent antagonistic property observed in the majority of the isolates. Based on the antagonistic properties, the Trichoderma isolates viz., TRSN1, TRMW2 and TRPN14 were selected for the protoplast fusion. During the protoplast isolation, the maximum number of protoplasts was obtained after 2 h of incubation of mycelia of parental isolates with the lytic enzyme. Protoplast fusion was carried out between the selected isolates (TRSN1 x TRPN14, TRSN1 x TRMW2, and TRPN14 x TRMW2) in the presence of poly ethylene glycol (PEG 6000). Three protoplast fusants were selected using carbendazim-amended PDA medium. The protoplast fusants displayed fast growth on PDA medium and completely covered the Petri dish at 5th of growth. The colony characters of fusants varied from light to dark green mycelium with fluffy growth and scattered to circular green heavy sporulation. In vitro screening of protoplast fusants against P. aphanidermatum and R. solani revealed that highest inhibition against P. aphanidermatum was observed with fusant 3 (84.4%) followed by fusant 2 (74.44%). Highest inhibition against R. solani was observed with fusant 2 (100%) followed by fusant 3 (70.30%). Antagonistic properties viz., antibiosis, lysis and overgrowth were observed in the protoplast fusants. Among the three protoplast fusants, fusant 1 exhibited all the antagonistic properties against both the pathogens with heavy sporulation. Thus, the present study has thrown light in understanding the potential of protoplast fusion in evolving improved strains of Trichoderma spp. Protoplast fusion enhanced sporulation in fusants compared to the parents. Further studies need to be conducted for the biochemical and molecular characterisation of parental isolates and fusants. The parents and protoplast fusants also have to be evaluated for their in vivo efficacy against soil borne pathogens in major crops of Kerala.ThesisItem Open Access Characterization of fungal pathogen associated with leaf rot disease of coconut (Cocos nucifere L.) and In Vitro evaluation of phylloplane microflora as biocontrol agents(Department of Plant Pathology, College of Agriculture, Vellayani, 2020) Deena, Sebastian; KAU; Radhakrishnan, N VLeaf rot disease (LRD) is a major foliar disease affecting coconut plantations of Southern Kerala especially in root (wilt) affected areas. In this context, the study entitled ‘Characterization of fungal pathogen associated with leaf rot disease of coconut (Cocos nucifera L.) and in vitro evaluation of phylloplane microflora as biocontrol agents’ was conducted in the Department of Plant Pathology, College of Agriculture, Vellayani during the year 2018-2020, with the objective to identify and characterize the major fungal pathogens associated with the LRD of coconut and in vitro evaluation of phylloplane microflora of coconut against the pathogens. The isolation of LRD pathogens was carried out from six taluks of Thiruvananthpuram district such as Thiruvananthapuram, Neyyattinkara, Nedumangad, Chirayinkeezhu, Kattakada and Varkala. Three locations were selected from each taluk and a total of eighteen samples were collected during the study. The results revealed that the disease in Thiruvananthapuram district was caused by a spectrum of pathogens such as Colletotrichum gloeosporioides, Fusarium spp., Gliocladium sp., and Scytalidium sp. The LRD was caused either by a single pathogen or by combinations of pathogens. C. gloeosporioides and Fusarium spp. were found as the major pathogens of LRD based on the frequency of isolation. Each and every isolate of the same pathogen differed from one another in cultural characters and virulence. All the pathogens produced water soaked brown lesion on artificial inoculation on detached spindle leaves; though the days taken for symptom initiation and size of the lesion developed varied. The isolate C3 (Isolate from Anayara, Thiruvananthapuram taluk) was found to be more virulent among the C. gloeosporioides isolates; and among the Fusarium spp. isolates, the isolate F5 (Isolate from Alamkode, Chirayinkeezhu taluk) was found to be more virulent. By observing the spore characters of the isolates, it was found that the spore size and pigmentation of the culture haven’t any significance to the virulence of the pathogen. Dual inoculation of the major pathogens on detached spindle leaves caused severe incidence of the disease compared to the individual inoculation of the pathogens. This result indicated that the LRD caused by fungal complex is more severe than that caused by individual fungal isolates. There are phylloplane fungi existing on healthy leaves of the infected palm with enough inhibition potential to LRD. The phylloplane fungal isolate PF5 showed more per cent inhibition to mycelial growth of C. gloeosporioides (54.44%) followed by the isolate PF4 (43.33%); and the isolate PF4 showed more inhibition to Fusarium sp. (64.44%) followed by the isolate PF5 (45.55%) in the dual culture assay. The detached spindle leaf assay also supported the same fact that the isolate PF5 was observed to be more suppressive to the disease caused by C. gloeosporioides (28.77%) and the isolate PF4 was reported to have more suppression to the disease caused by Fusarium sp. (34.56%). These pre-treatment effects are more promising than Pseudomonas fluorescens PN026, but inferior to copper oxy chloride (0.2%). Thus, the present study revealed that the LRD of coconut in Thiruvananthapuram district is caused by a combination of pathogenic fungi viz., C. gloeosporioides, Fusarium spp., Gliocladium sp., and Scytalidium sp. Prophylactic application of the phylloplane fungal isolates PF4 and PF5 could reduce the LRD severity in vitro to a promising level and these isolate can be further tested for in vivo biocontrol potential before going for the development of a formulated product.ThesisItem Open Access Management of stem rot and foliar blight of cowpea (Vigna unguiculata (L.) Walp.)(Department of Plant Pathology, College of Agriculture, Padannakkad, 2020) Nayana Sunil, M V.; KAU; Susha S, TharaABSTRACT Management of stem rot and foliar blight of cowpea (Vigna unguiculata (L.) Walp.) Cowpea (Vigna unguiculata (L.) Walp.) is one of the highly demanding, nutritionally rich vegetable and legume crops cultivated in Kerala throughout the year. Stem rot and foliar blight disease in cowpea was emerged as a serious disease in farmer’s fields especially during monsoon period and resulted in severe yield reduction and economic loss. Hence present study was undertaken during 2018-2020 with an aim of identifying and characterizing fungal pathogen causing stem rot and foliar blight disease in cowpea and to evaluate biocontrol agents and chemical fungicides against it. Cowpea plants showing symptoms of stem rot and foliar blight disease were collected from six locations of Kasargod district such as Cheemeni, Pallikkara, Nileswar, Trikaripur, Udinur and Periya showing disease incidence ranging from 12 to 80 % and percent disease index of 8 to 51 %. Highest disease incidence recorded at Nileswar and lowest at Periya. Six isolates obtained were named with index ‘Sr’ such as Sr1, Sr2, Sr3, Sr4, Sr5 and Sr6. Pathogenicity test of six isolates were done in cowpea by soil inoculation and leaf inoculation methods. Isolate Sr3 produced symptom on stem at 2nd day and on leaf at 24 h of inoculation which was earlier than other isolates. Area of water soaked lesion on stem (6.4 cm2) and leaf (9.6 cm2) was also highest for Sr3 and observed fastest radial growth compared to others and covering 90 mm petridish at third day of inoculation. Based on disease development and growth rate on PDA, Sr3 was considered as most virulent isolate. Pathogen was identified based on cultural, morphological and molecular characterestics. Cottony and fluffy pure white colony with light zonation and presence of two types of fungal hyphae with clamp connection were observed. Two types of sclerotial bodies were detected and cross section of sclerotium revealed the presence of different layers such as outer thick skin, rind, cortex and medullary cells under compound microscope. Molecular identification based on D1/D2 region of LSU revealed 99.61 % similarity with Athelia rolfsii. Based on all these characteristics isolate Sr3 was identified as Sclerotium rolfsii. Symptoms associated with stem rot disease were water soaked lesion at the basal region of stem followed by wilting, yellowing of the aerial parts, necrosis, girdling and rotting of the stem. White mycelia and sclerotial bodies were formed at the infected portion. Foliar blight disease showed water soaked lesion on the leaf with concentric ring formation. Both mycelia and sclerotial bodies were also produced over the lesion. Effect of biocontrol agents on S. rolfsii tested by dual culture method explained higher inhibition per cent of Trichoderma harzianum followed by Trichoderma viride. Bacterial biocontrol agents showed least potential of antagonism in which Pseudomonas fluorescens exhibited zero inhibition on pathogen. Among the fungicides tested against S. rolfsii by poisoned food method, mancozeb 75WP (0.1 %, 0.2 % & 0.3 %) and propiconazole 25EC (0.05 %, 0.1 % & 0.2 %) were found best having 100 % inhibition over the pathogen whereas copper oxychloride 50 WP (0.1 %, 0.2 % & 0.3 %) and carbendazim 50WP (0.05 %, 0.1% & 0.2 %) were not effective. Compatibility of mancozeb, propiconazole and chlorothalonil were tested with T. harzianum and T. viride. Mancozeb (0.2 %) exhibited 100 % compatibility with T. harzianum and 92.39 % with T. viride. Propiconazole (0.1 %) was highly (100 %) incompatible with both of these followed by chlorothalonil (0.2 %). Field evaluation with most efficient fungicides, biocontrol agents and combination of both were experimented on cowpea (variety: Kanakamani) in pot culture method. Pre-sowing drenching with post sowing drenching and spraying of mancozeb (0.1 %) and propiconazole (0.05 %) at 20, 40, 60 days of sowing were found best for the management of stem rot and foliar blight disease having BC ratio of 1.9 followed by combinations of mancozeb and Trichoderma sp. Among the biocontrol agents T. harzianum were found superior than T. viride. Hence soil drenching at 7 days before sowing and soil drenching and aerial spraying at 20, 40, 60 days after sowing with mancozeb (0.1 %) or propiconazole (0.05 %) or mancozeb-Trichoderma combinations or T. harzianum (2 %) can be recommended for management of stem rot and foliar blight disease in cowpea. future line of work should be focused on field level study of stem rot and foliar blight disease in other districts of Kerala and to evolve local specific management with native isolates of biocontrol agents and their metabolites.
