PG Thesis
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Item Wild edibile mushroom Termitomyces spp. for mycoprotein production(Department of Plant Pathology, College of Agriculture,Vellayan, 2023-03-31) Anukrishna V J.; Susha, S TharaThe present study entitled “Wild edible mushroom Termitomyces spp. for mycoprotein production, was conducted at Department of Plant Pathology, College of Agriculture, Vellayani during 2020-2022 with an objective to collect and identify the native isolates of Termitomyces spp., in order to determine the optimal conditions for mycelial biomass cultivation and, exploiting the potential of this mushroom for mycoprotein production. A survey was conducted in agro ecological units 8, 9 and 12 of Kerala, during the South West and North East monsoon periods of 2021 and 2022. Twenty six native isolates of Termitomyces were collected from Thiruvananthapuram and Kollam districts. The most distinguishing characters of this mushroom is the presence of an umbonate cap with a prominent perforatorium and a subterranean pseudorhiza. Identification of species were carried out based on macro and micro morphological characters. The macro-morphological characterisation revealed that the cap size varies enormously between the species. The colour of the cap varied from white-cream to grey, light brown to dark brown between species. The pseudorhiza length varied from none (Termitomyces microcarpus) to 35 cm (Termitomyces heimii). The stipe was mostly cylindrical, smooth and glabrous. The spore print was pink in colour. Micro- morphological characterisation revealed that the basidia (18- 30 μm x 5 -9.5 μm) were clavate, bearing four sterigmata, cystidia (24-49 μm x 8-28 μm) were clavate to pyriform, hyaline and the basidiospores (5.5-8.5μm x 3.5-6 μm) were hyaline, ovoid to ellipsoid in nature. Based on morphological characteristics, twenty six Termitomyces samples were identified as ten species. The species confirmed through molecular characterization include Termitomyces eurrhizus, Termitomyces striatus, Termitomyces cylindricus, Termitomyces fuliginosus, Termitomyces microcarpus (large form and small form), Termitomyces radicatus, Termitomyces robusts, Termitomyces sp (1), Termitomyces sp (2) and Termitomyces heimii. Among the nine species, Termitomyces sp (1) and Termitomyces sp (2) were identified as two new species of Termitomyces, the first record from Kerala. It was observed that T. microcarpus (large form and small form) was the most commonly occurring and widely distributed species in Thiruvananthapuram and Kollam districts followed by T. fuliginosus. Cultural studies showed that potato dextrose peptone agar was the best media for mycelial growth of Termitomyces spp. Significantly the largest colony diameter and highest biomass yield of all isolates were observed on potato dextrose peptone agar. Termitomyces eurrhizus (best isolate) showed the largest colony diameter (7.800 cm ±0.100) and biomass yield (1.675 ± 0.006) when compared with other isolates. The growth response of T. eurrhizus to various carbon sources in basal medium (potato dextrose peptone broth) was tested. Higher mycelial biomass production was found in dextrose as carbon source. Peptone was the best nitrogen source to promote higher mycelial production. The optimum temperature, pH and light intensity were identified as 300C, 5.5 and 2000 lux respectively. Mycelial production was nil at 150C, 200C and 350C. The lower and higher pH (4.5 and 7.5) retarded the mycelial growth. The best two isolates (T. eurrhizus, and T. fuliginosus) were used for mycoprotein production. Pelletization was achieved in 100 ml potato dextrose peptone broth of pH 5.5 at 150 rpm in light (2000 lux) after incubation for 20 days at 29±10C. The two isolates produced good pellets evidenced by micro and macro pellets. Spherical to oval compact pellet morphology was common. The most promosing srain was T. eurrhizus which produced brownish to light orange coloured smooth spherical to oval compact pellets (diameter: 1-12 mm). T. fuliginosus produced whitish to light brown coloured pellets (1-11 mm). The proximate analysis of mycoprotein pellet revealed the constituents including crude protein (25. 7%), carbohydrate (36. 59%), fibre (9.91%) fat (3%) and ash (12.3%). The protein content was found to be more in the pellet (25.7%) as compared to the mushroom fruiting body (21.48%). In view of difficulty of domestication of the wild edible mushroom, Termitomyces spp., the only way to exploit the potential is through mycelial biomass production by submerged culture. The present study revealed the possibility of utilizing T. eurrhizus and T. fuliginosus for mycoprotein production.Item Etiology and management of sheath rot disease of rice(Department of Plant Pathology, College of Agriculture, Vellayani, 2023-03-16) Boya Sreekanth.; Surendran, MThe study entitled "Etiology and management of sheath rot disease of rice" was conducted at Department of Plant Pathology, College of Agriculture Vellayani and Rice Research Station, Moncompu during 2020-2022, with the objective to isolate and characterize the pathogen associated with sheath rot disease of rice and evaluate the efficacy of the available Bacillus sp.and commercial fungicides against sheath rot disease of rice. Purposive sampling survey conducted in four rice growing districts of Kerala during 2021-2022 to collect the sheath rot infected panicles and to access the disease incidence (DI) and disease severity (DS). Among the surveyed locations, maximum DI (49.23 per cent) and DS (46.32 per cent) were recorded from Neelamperoor and Palakkad. S. oryzae was isolated from the collected specimens; a total of five pure cultures of S. oryzae (Isolate I1 to Isolate I5) were obtained and Koch's postulates were proved for all the isolates in rice var. Uma. All the S. oryzae isolates were screened for its virulence and pathogenicity in rice var. Uma. The isolate I5, from Thrithala produced the symptom within 24 h of artificial inoculation. On 4th day of artificial inoculation, isolate I5 recorded a maximum lesion size of 2.50 cm; and thus, concluded as the most virulent isolate. The cultural characters of these 5 isolates were whitish orange with some radial foldings and morphological characters of hyphae was septate and whitish orange in color and spores single celled and cylindrical in shape. Average size of the spore was 5.53 x 1.66 µm. Dual culture assay of Bacillus sp. B15, Bacillus sp. B17, Bacillus sp. B33, Bacillussp. B42 and Pseudomonasfluorescens(PN026) in potato dextrose agar (PDA) medium indicated that the beneficial endophytic bacteria significantly inhibited the growth of the pathogen through multiple antagonistic properties. Maximum growth inhibition of S. oryzae (70.95 per cent) by P. fluorescens (PN026) followed by Bacillus sp. B17 (64.45 per cent) and Bacillus sp. B 42 (50.95 per cent) were observed on 12 th day of dual culturing. Among the four commercial fungicides tested in vitro, trifloxystrobin 25%+tebuconazole 50 % 75 WG (400ppm), propineb 50 WP (2500ppm) and hexaconazole 5EC (2000ppm) completely inhibited (100%) the sheath rot pathogen compared to copper hydroxide 77 WP (2000ppm) which inhibited the growth of the sheath rot pathogen by 86.42% per cent. Considering the overall performance, recommended doses of trifloxystrobin 25%+tebuconazole 50 % 75 WG (400ppm), propineb 50 WP (2500ppm) and hexaconazole 5 EC (2000ppm) were more effective against sheath rot pathogen. The isolation of DNA from sheath rot pathogen was carried out by using CTAB (cetyltrimethyl ammonium bromide) method of DNA isolation. Quality and quantity of sample DNA were 1.73 and 60 µg ml-1 . Size of the amplicon is 608bp. This sheath rot associated pathogen was identified from Rajiv Gandhi Centre for Biotechnology (RGCB), Thiruvananthapuram as Sarocladium oryzae through molecular characterization (GenBank Accession no. OP716814). This sheath rot pathogen was used for further studies. Pot culture experiment was conducted for screening rice varieties (20 numbers) for resistance to sheath rot pathogen. Artificial inoculation was done at panicle initiation stage. Aathira and Shreyas showed tolerant reaction to sheath rot disease whereas Uma variety showed the highest susceptibility nature. The biocontrol agents and fungicides were evaluated in the field against sheath rot disease of rice during Kharif 2022 at RRS, Moncompu. Management of disease before panicle emergence is very much essential. Prophylactic application of talc-based formulation of Bacillus sp. B15, Bacillus sp. B17, Bacillus sp. B33, Bacillus sp., B42, B 15+ B17+ B 33+ B 42 consortium and Pseudomonas fluorescens (PN026) as seed treatment (10g kg-1 ) + soil application (1kg/acre) + foliar spray (20g L-1 of water at booting stage) for the management of sheath rot disease of rice and thereby improving the yield. Among all the bioagent treatments, the application of B 15+ B 17+ B 33+ B 42 consortium showed more efficacy nature for the management of sheath rot disease of rice and improving the yield. Four commercial fungicides viz., copper hydroxide 77 WP @ 2 g L-1 , trifloxystrobin25%+tebuconazole 50 % 75 WG @ 0.4 g L -1 , propineb 50 WP @ 2.5 g L -1 and hexaconazole 5 EC@2 ml L-1 were given as foliar spraying at booting stage. Among all the fungicides tested in the field, trifloxystrobin 25%+tebuconazole 50 % 75 WG @ 0.4 g L -1 and hexaconazole 5 EC@ 2 ml L-1 applied as foliar spraying were significantly superior in reducing the disease and increasing the yield followed by propineb 50 WP @ 2.5 g L-1 and copper hydroxide 77 WP @ 2 g L-1 . Benefit cost ratio was also more in case of B 15+ B 17+ B 33+ B 42 consortium and trifloxystrobin 25%+tebuconazole 50 % 75 WG @ 0.4 g L-1 . Thus, the present study revealed that sheath rot of rice could be managed by using Bacillus sp. B 15+ B 17+ B 33+ B 42 consortium as seed treatment (10g kg-1 ) + soil application (1kg/acre) + foliar spray (20g L-1 of water at booting) and commercial fungicide, trifloxystrobin 25%+tebuconazole 50 % 75 WG @ 0.4 g L -1 and hexaconazole 5 EC at 2 ml L -1 . The results may be subjected to multi-location and multi- seasonal field trails before recommendation. The compatibility of Bacillus sp. consortium with new generation fungicides and the residue of fungicides in grain may further be studied.Item Etiology and management of bacterial wilt of yard long bean(Department of Plant Pathology, College of Agriculture, Vellayani, 2023) Talla Sushmitha; Sajeena AThe study entitled “Etiology and management of bacterial wilt of yard long bean” was conducted at College of Agriculture, Vellayani and Integrated Farming System Research Station (IFSRS), Karamana during 2020-2022 with an objective to identify and characterize the bacterium inciting wilt disease in yard long bean and management of the disease. Bacterial wilt infected yard long bean plant samples were collected from Vamanapuram (8.7226° N, 76.8971° E) and Nanniyode panchayat (8.6988° N, 77.0262° E) of Thiruvananthapuram district, Kerala. The disease incidence was 85 to 90 per cent. The disease symptoms included drooping and wilting of green leaves, collapse of stem followed by death of plants. The bacterium was isolated on triphenyl tetrazolium chloride (TZC/TTC) medium and three methods of pathogenicity tests viz., root dip, root dip and stem injection as well as soil inoculation were undertaken to prove Koch's postulates. The symptoms were observed within three to seven days after inoculation and complete wilting was observed in 7, 10 and 14 days in root dip, root dip and stem injection and soil inoculation respectively. Cultural studies revealed the bacterial colonies to be white or cream, circular, smooth, convex in casamino acid peptone glucose agar (CPG) and white, circular, smooth, convex, fluid like with pink colouration at centre in TZC medium which were the best media for the bacterial growth. Morphological and biochemical studies revealed the bacteria as gram negative, rod-shaped and facultative anaerobic. Molecular characterization using the universal primers of 16S rRNA viz., 27F/1492R revealed 99.83 per cent identity with several isolates of Enterobacter spp. and Kosakonia oryzae and the gene amplified using CM7F/CM31b primers of rpoB, one of four house-keeping genes of Enterobacteriaceae revealed 99.72 per cent identity with Kosakonia oryzae strain Ola51. The 16S rRNA and rpoB sequence were deposited in NCBI database (Acc. no. OP321041 and Acc. no. OP321041 respectively). Further, phylogenetic analysis and biochemical characterization using Enterobacteriaceae specific kit confirmed the pathogen to be K. oryzae. 142 In vitro evaluation of various chemicals by poisoned food technique and filter paper assay revealed that streptocycline (250 ppm) was the most effective bactericide resulting in a mean inhibition zone of 27.67 mm, followed by copper oxychloride 50 % WP (0.30 %) (17.00 mm) and copper hydroxide 77% WP (0.20 %) (15.33 mm). Among the various botanicals screened for antibacterial effect in vitro by paired plate technique, bulbs of Allium sativum revealed the highest inhibition of bacterial growth followed by leaves of Mansoa alliaceae. In agar well diffusion method, bulbs of A. sativum (15 %) followed by leaves of Boerhavia diffusa (20 %) and M. alliacea (20 %) resulted in maximum inhibition (inhibition zone of 20.33, 18.83, 16 mm respectively) of the bacterial growth. An in vivo study was undertaken at IFSRS, Karamana for the management of bacterial wilt disease in yard long bean (var. Geethika) using the best three treatments viz., bulbs of A. sativum (10g per pit), copper oxychloride 50% WP (0.30 %) and copper hydroxide 77 % WP (0.20 %) selected from in vitro studies along with streptocycline (250 ppm), bacteria inoculated and uninoculated treatments as checks. The inoculated control revealed 100 per cent disease incidence whereas soil application of crushed garlic bulbs (10 g/pot at one week before transplanting) followed by immediate covering with cow dung and soil mixture, seedling treatment and soil application of crushed garlic bulbs at 10, 20 and 30 days after transplanting (DAT) registered the minimum disease incidence (13.33 %) with the maximum number of pods (43), pod length (46.82 cm), pod weight (21.67 g) and pod yield (815.13 g) followed by soil application of copper oxychloride 50 % WP (0.3 %) (754.77 g pod yield) with 20 per cent disease incidence. Treatment application at 10, 20 and 30 DAT with 10 days interval (DI) was more effective than at 15, 30 and 45 DAT with 15 days interval. Biochemical studies on identifying the mechanism of disease toleItem Phaeophycean seaweed extracts(PSWE): exploration of its antifungal and bio-elicitor properties against major fungal diseases of black pepper(Department of Plant Pathology, College of Agriculture, Padannakkad, 2023-09-15) Abinaya, B; Sajeesh, P KThe present study entitled “Phaeophycean seaweed extracts (PSWE): Exploration of its antifungal and bio-elicitor properties against major fungal diseases of black pepper” was conducted in the Department of Plant Pathology, College of Agriculture, Padannakkad during 2021-2023. Plant samples of black pepper showing typical symptoms of foot rot and anthracnose were collected, and identified through cultural, morphological, and molecular characterizations, as Phytophthora capsici in case of foot rot and Colletotrichum sp. in case of anthracnose. Marine brown algal samples were collected, and the extracts were prepared through four different methods, including acid, alkali, solvent and hot water extraction. The antifungal activity of the phaeophycean seaweed extract (PSWE) at different concentrations was tested using the poisoned food technique (PFT). Hot water extract at 5000 ppm (PSWE (HW 5000)) was recorded as the highest inhibition (100%) of mycelial growth against P. capsici. In case of Colletotrichum sp., hot water extract at 5000 ppm exhibited 20 per cent inhibition. Further, the stability of the active principle in PSWE against high temperature and exposure to sunlight was tested using PFT and agar well diffusion assay (AWDA) against P. capsici. It was found that the active principle was degraded by the high temperature at (121℃ for 20 min.) and sunlight (min. temp. 28℃ and max. temp. 37℃). In PFT, zero per cent inhibition was recorded in high temperature, and 24.76 per cent inhibition was observed in sunlight-exposed PSWE. 17.11 per cent of mycelial inhibition was recorded when treated with high temperature, and 36.6 per cent of inhibition was recorded when exposed to sunlight. The protein and non-protein fractions of the extract were separated using the chloroform: methanol method and tested for antifungal activity. The protein fraction of the extract contributed to 40 per cent of mycelial inhibition through PFT. The molecular weight of the protein fraction was found to be more than three kDa, and the protein fraction with less than three kDa size recorded 42.5 per cent of mycelial inhibition. The size of protein fractions was analysed through SDS-PAGE as 75 kDa to 150 kDa. PSWE (HW 5000) was selected for a pot culture experiment with 12 treatments using the variety Panniyur 1 against foot rot pathogen P. capsici. The treatments were applied, and seven days after inoculation, the least per cent lesion development (PLD) of 33.33 per cent, as well as the least lesion size (3.42 cm), was recorded in PSWE (HW 5000) treatment with pre-inoculation of the pathogen through soil drenching and foliar spray. The highest PLD, 73.33 per cent, and lesion size (5.77 cm) was recorded in PSWE HW (5000) with post-inoculation of the pathogen via soil drenching. Biochemical basis of defense induction in the host plant by PSWE (HW5000) was analysed through the expression of defense-related enzymes. Application of PSWE (HW 5000) through soil drenching and foliar application with pre-inoculation of the pathogen (T5) and same treatment without pathogen inoculation (T9) expressed higher activity of defense-related enzymes such as polyphenol oxidase, peroxidase, superoxide dismutase and catalase. The presence of reactive oxygen species (ROS) was assessed using nitroblue tetrazolium (NBT) and diaminobenzidine (DAB) staining techniques. The build-up of superoxide ions and H2O2 were observed in the leaves of pathogeninoculated plants by their corresponding colour development. In both staining techniques, T5 and T6 exhibited reduced stain intensity compared to plants in control. It was found that PSWE (HW 5000) has noticeable growth promotion activity in black pepper. The growth promotion was highest in the application of PSWE (HW 5000) via soil drenching and foliar application (T9), followed by soil drenching (T7) of PSWE (HW 5000) and soil drenching and foliar application with pathogen inoculated plants (T5). The number of leaves (36.44), shoot and root length (165 and 21.83 cm), shoot and root biomass in fresh weight basis (47.66 and 14.33 g) and in dry weight basis (15.85 and 5.25 g) was higher in T9. The present study revealed that the PSWE (HW 5000) has effective inhibition activity against P. capsici and Colletotrichum sp., and it is effective in managing foot rot disease in black pepper under controlled conditions through the induction of host defense enzymes. Moreover, it enhances plant growth in black pepper. The signaling pathways associated with defense actions and growth promotion mechanisms have to be investigated.Item Endospore-forming endophytic bacteria for the management of tospovirus infection in COWPEA(Vigna unguiculata ssp. sesquipedalis)(Department of Plant Pathology, College of Agriculture, Vellayani, 2023-09-25) Ramseena, S R; Ayisha, RThe study entitled “Endospore-forming endophytic bacteria for the management of Tospovirus infection in cowpea (Vigna unguiculata ssp. sesquipedalis)” was carried out at College of Agriculture, Vellayani during 2021-2023 with an objective of evaluating the efficacy of Endospore-forming Endophytic Bacteria (EEB) for the management of Tospovirus causing bud necrosis in cowpea (Vigna unguiculata ssp. sesquipedalis). The virus was sap transmissible and was maintained in local lesion host, Chenopodium amaranticolor and susceptible cowpea variety, Pusa Komal by mechanical inoculation using potassium phosphate buffer. On mechanical inoculation to chenopodium plants, cowpea Tospovirus isolate took 4-5 days for symptom development and produced chlorotic and necrotic lesions. In cowpea variety Pusa Komal it took 8 days for symptom development and produced both local and systemic infections. The virus that causes cowpea bud necrosis disease was identified serologically using ELISA and DIBA, and it was discovered that Tospovirus isolation from several cowpea samples demonstrated a close relationship with Watermelon silver mottle virus (WSMoV). Molecular detection was done by RT-PCR and an expected amplicon of size 477–500 bp was obtained using the primer specific to the coat protein gene of Groundnut bud necrosis virus (GBNV). Serological and molecular detection confirmed that the virus associated with bud necrosis of cowpea belong to the serogroup IV which is Watermelon silver mottle orthotospovirus. Screening of five different Bacillus strains was done for evaluating its efficacy in managing cowpea bud necrosis disease. Bacillus pumilus VLY17, Bacillus amyloliquefaciens VLY24, Bacillus velezensis PCSE10, Bacillus amyloliquefaciens CBSE5 and Bacillus velezensis CBRE5 were used for screening. Pre and post inoculation with EEBs in C. amaranticolor and susceptible cowpea variety Pusa Komal were carried out and B. pumilus VLY17 treated plants demonstrated reduced number of local lesions (4) in C. amaranticolor, when compared to that of virus inoculated control with a significantly higher number of local lesions (11). In cowpea, the plants pre colonised with B. pumilus VLY17 were observed with low vulnerability index of (V I) (20) compared to untreated plants with a V I of 66.6. Hence, B. pumilus VLY17, with good disease-suppressing ability, was selected and further evaluated against the virus in tolerant cowpea variety, Githika, to standardise the effective method of application. The most efficient strategy of treating EEB, according to the analysis of different application techniques, was seed priming followed by foliar spray and drenching with a suspension of B. pumilus at 108 CFU per ml at cotyledonary leaf stage of cowpea plants compared to the untreated ones. The number of branches (19), fresh weight (163.6 g) and number of pods (19) obtained from B. pumilus VLY17 treated plants showed a significant increase than that of the virus control plants. The treated plants also flowered 3-4 days earlier than the virus control and exhibited considerable resistance towards further pest and disease occurrence. When analysed the enzyme activity over 3 weeks in different treatments, enzyme activity of polyphenol oxidase and phenylalanine ammonia-lyase was found to be higher at second week and peroxidase activity was higher at the third week in treated plants. On analysis of the average of enzyme activity over 3 weeks, peroxidase (74.1 μg/g of leaf tissue min -1), polyphenol oxidase (6.23 μg/g of leaf tissue min -1) and phenylalanine ammonialyase (72.7 μg of cinnamic acid per gram of leaf tissue) were found to be high in treatment, where seed priming followed by soil drenching and foliar spray at cotyledonary leaf stage prior to the virus inoculation was applied. Total protein content (49.9 μg of BSA per gram of leaf tissue) was also found to be higher in treated ones when compared to the untreated ones at second week. Expression of defense genes such as NPR1, Coi1, PAL and BGL were analysed in treated and virus control plants by RT-PCR and ImageJ software. The analysis showed that seed treatment followed by foliar spray and drenching with B. pumilus VLY17 at the cotyledonary leaf stage of cowpea plants prior to virus inoculation, gave the highest expression of defense genes such as NPR1 (46.18), Coi1 (31.56) and PAL (25.59) in terms of band peak percentage compared to the virus inoculated and absolute control plants. The BGL gene expression (33.55) was found to be less in B. pumilus VLY17 seed primed plants than the virus control plants. There are reports establishing that BGL gene expression is controlled by the virus in infected plants as it helps in the movement of the virus by hydrolysis of callose, deposited in plasmodesmata, formed as a part of defense due to virus infection. Hence, less activity of BGL gene is indicating more defense as it can hinder the movement of virus. The research highlights the biocontrol potential of B. pumilus VLY17 to reduce the disease severity by enhancing the expression of defense genes and by promoting growth and yield parameters of cowpea plants. Seed priming with B. pumilus VLY17 for 4 hours followed by soil drenching and foliar spray at cotyledonary stage of cowpea is the best method of application of B. pumilus VLY17 for the management of bud necrosis disease in cowpea.Item Management of virus disease complex in chilli using the beneficial fungal root Endophyte Piriformospora indica(Department of Plant Pathology, College of Agriculture, Padannakkad, 2023-09-15) Meera Nair, V; Radhika, N SThe research work, “Management of virus disease complex in chilli using the beneficial fungal root endophyte Piriformospora indica” was undertaken in the Department of Plant Pathology, College of Agriculture, Padannakkad during 2021- 2023 with the objective to explore the use of the beneficial fungal root endophyte Piriformospora indica for the management of chilli leaf curl virus complex infecting chilli.Infected plant samples were collected from the chilli plots in the Instructional Farm, College of Agriculture, Padannakkad. The chilli variety Anugraha recorded higher disease incidence (D.I.-66 per cent) and vulnerability index (V.I.-15.66) than the local variety (D.I.-64 per cent and V. I. - 14.66 per cent). The major symptoms observed in the fields were leaf curling, puckering and swelling of veins. Molecular detection for the presence of associated viruses was done with begomovirus coat protein specific primers viz., Deng and AV/AC yielded amplicons of 520 bp and 575 bp respectively confirming its association with the disease. RT- PCR with Cucumber mosaic virus (CMV) coat protein specific primers could not detect the presence of CMV. Chilli seeds of variety Vellayani Athulya were sown on P. indica mass-multiplied coir pith-cow dung mixture (1:1) amended with 2 per cent gram flour. Chlamyodspores of P. indica were observed in the root cortical region five days after co-cultivation (DAC). Seeds sown on P. indica mass multiplied medium germinated early (seven days) and completed 50 per cent germination within ten days compared with untreated seeds (ten days for germination and 17 days for 50 per cent germination). Pot culture experiments were conducted with seven treatments and eight replication in a completely randomized design (CRD). The virus was transmitted through wedge grafting at intervals of 2, 5, 10, and 15 days. Pre-colonization of P. indica followed by graft transmission of the virus after 15 days took 28 days for symptom expression while non-colonized, grafted plants took 13 days. Pre-colonized plants expressed low V.I. (25) against noncolonized, grafted plants (64) at 45 DAT. Colonization of P. indica (2 days) after graft transmission of the virus recorded a V.I. (36) at 45 DAT and took 15 days for symptom expression while non-colonized grafted plants recorded a V.I. (65) and took 12 days for symptom expression. PCR amplification using virus specific primers confirmed the transmission of the virus in all grafted treatments. Field study laid out in the Instructional Farm I, College of Agriculture, Padannakkkad with P. indica colonized and non-colonized chilli seedlings of variety Vellayani Athulya recorded per cent D.I. (74) and V.I. (14.66) while the non-primed plants recorded a D.I. (86) and V.I. (32.27) at 90 days after transplanting. Amplicons in agarose gel electrophoresis confirmed that the virus titre in P. indica colonized chilli plants was significantly lower compared to those in control. P. indica colonization recorded improved growth characteristics such as the number of leaves (72.53), leaf area (30.59 cm2) and number of branches (10.78) compared to the non-colonized plants. The days taken for flowering (18.22) was early and the number of fruits per plant increased (68.23) significantly in P. indica colonized plants. P.indica colonized plants recorded a yield of 683 g while non-colonized plants yielded 480.29 g per plant. Mites and mole crickets along with diseases like powdery mildew and fruit rot were also observed. Biochemical basis for P.indica conferred tolerance was estimated based on reactive oxygen species (ROS) and hydrogen peroxide production and the activity of defense related enzymes. The presence of ROS was assessed using nitro blue tetrazolium (NBT) and H2O2 by diaminobenzidine (DAB) staining techniques. Intense colour development was obtained in non-colonized plants inoculated with the virus. Plants pre and post-colonized with P. indica exhibited reduced stain intensity compared to plants containing only the virus with the pre-colonized plants showing better stain reduction than the post-colonized ones. The ROS scavenging enzymes include catalase, peroxidase, superoxide dismutase and phosphatase activity was higher in pre-colonized plants than in post-colonized plants. Plants infected only by the virus expressed a significant reduction in the activities of catalase, peroxidase, superoxide dismutase, phosphatase, and total soluble protein compared to pre-colonized plants at all time intervals. However, at the final harvest, this treatment exhibited an increase in total protein although still lower than pre-colonized plants. The present study revealed that P. indica is effective in managing chilli leaf curl disease both in controlled and open field condition by increasing the production of ROS scavenging enzymes. P. indica was found to improve the germination, growth and development of chilli plants of variety Vellayani Athulya. Gene expression studies in future can unravel the tripartite interaction between plant, virus and the endophyte in rendering tolerance to plants against virus and enhancing plant growth.Item Management of postharvest anthracnose of banana using green nanoparticles(Department of Plant Pathology, College of Agriculture , Vellayani, 2023-12-16) Ajay, B; Susha S TharaA study entitled ‘Management of postharvest anthracnose of banana using green nanoparticles’ was conducted during 2021-23 at Department of Plant Pathology, College of Agriculture, Vellayani with the objective to characterize the major pathogen associated with anthracnose of banana fruits and its management using green nanoparticles. A survey was conducted in local markets of five agro-ecological units of Kerala viz., AEU 1, AEU 3, AEU 8, AEU 9 and AEU 12 covering Thiruvananthapuram, Kollam and Alappuzha districts. A total of 34 locations were surveyed during 2021-23 to collect the diseased specimens of banana Nendran variety (Musa AAB) and to study the symptomatology of the disease. Variations in symptoms were noticed from different locations such as black or brown sunken spots of various sizes, shriveling of fruits and spots having triangular shaped or angular edges. The pathogens were isolated from the collected specimens; a total of 62 isolates were obtained out of which 34 isolates were Colletotrichum sp. and Koch’s postulates were proved in matured harvested dehanded banana. All the 34 Colletotrichum sp. isolates were screened for its virulence and pathogenicity. The isolate K1B1 from Kollam corporation (AEU 1- Kollam district) recorded the highest Percent disease index (PDI) of 83.33 per cent with a highest lesion size of 5.10 x 4.95 cm on the 5th day of artificial inoculation; and hence concluded as the most virulent isolate. Cultural and morphological studies of isolate K1B1 were carried out. Initially white to grey floccose aerial mycelium was observed which turns orange colour with age. Microscopic studies revealed that mycelia were hyaline and septate, acervulus were brown without setae, conidia were hyaline aseptate with elliptical or cylindrical shape and appressorium were dark brown and irregular shaped. Based on the cultural and morphological studies, isolate K1B1 was identified as Colletotrichum musae. Further molecular characterization of the isolate K1B1 was done using ITS primers and the isolate was confirmed as Colletotrichum musae. In vitro evaluation of prepared essential oil nanoemulsions (NEs) viz., cinnamon oil NE, clove oil NE, basil oil NE, neem oil NE and mustard oil NE at 0.5 %, 1 % and 2 % against C. musae in PDA by poisoned food technique revealed that all the essential oil NEs significantly reduced the growth of C. musae over control. The highest inhibition (100 %) at the lowest concentration (0.5 %) was observed in cinnamon oil NE and clove oil NE followed by basil oil NE (96.66 %). In vitro evaluation of prepared green copper nanoparticles (CuNPs) synthesized using leaf extracts of neem, ocimum, clove, American mint, and cinnamon at 0.05 %, 0.1 % and 0.2 % against C. musae by poisoned food technique revealed that all the synthesized green CuNPs significantly reduced the growth of C. musae over control. The highest inhibition (100 %) at the lowest concentration (0.05 %) was observed in green CuNPs synthesized using leaf extracts of cinnamon and clove followed by green CuNPs synthesized using leaf extracts of neem (97.58 %). In vitro evaluation of chitosan NPs (60 nm) at 0.5 %, 1 % and 2 % in comparison with the best three treatments from essential oil NEs (cinnamon oil NE, clove oil NE and basil oil NE at 0.5 %) and green CuNPs (Synthesized using leaf extracts of cinnamon, clove and neem at 0.05 %) against C. musae by poisoned food technique revealed that the essential oil NEs and the green CuNPs significantly reduced the growth of C. musae over control. Chitosan NPs didn’t show any reduction in the growth of the pathogen.The highest inhibition (100 %) at the lowest concentration was observed in cinnamon oil NE (0.5%), clove oil NE (0.5%), green CuNPs synthesized using leaf extracts of cinnamon (0.05%) and clove (0.05%) followed by green CuNPs synthesized using leaf extracts of neem (97.58 % at 0.05%). Based on the results of in vitro evaluation, the best five treatments (cinnamon oil NE, clove oil NE, green CuNPs synthesized using leaf extracts of cinnamon, clove and neem) were taken for in vivo studies along with carbendazim (0.1 %), pathogen inoculated control and uninoculated control. All the tested green NPs significantly reduced the lesion formation in matured harvested dehanded banana. Lowest lesion size of 0.86 cm and 1.46 cm was recorded in green CuNPs synthesized using leaf extracts of cinnamon and clove respectively followed by cinnamon oil NEs (2.60 cm). Similarly, the highest percent disease reduction over control was observed in green CuNPs synthesized using leaf extracts of cinnamon (99.01 %) and clove (98.28 %) followed by cinnamon oil NE (97.56 %). The best three green NPs (Green CuNPs synthesized using leaf extracts of cinnamon and clove and cinnamon oil NE) from in vivo studies were characterized. The formation of green CuNPs synthesized were confirmed by a characteristic peak obtained at 800 nm by UV-Vis spectroscopy.The results from FT-IR (Fourier transform infrared spectroscopy) analysis conclude that the surface of synthesized CuNPs were capped and stabilized by flavonoids and other phenolic compounds in the leaf extracts. The morphological characterization of CuNPs using FESEM (Field emission scanning electron microscopy) and HRTEM (High resolution transmission electron microscopy) revealed the presence of spherical particles with some agglomeration and the size of the particles was found to be in the range of 20 – 60 nm. DLS (Dynamic light scattering) analysis was used to find out the surface charge of NPs and the negative zeta potential was found at -22.2 mV, -21.7 mV and -25.8 mV for green CuNPs synthesized using leaf extracts of cinnamon, clove and cinnamon oil NE respectively. The X-ray diffraction (XRD) analysis of green CuNPs revealed the crystalline structure of CuNPs. The shelf life and organoleptic properties (appearance with and without skin, colour with and without skin, texture, taste, flavor and overall acceptability) of the banana fruits treated with green nanoparticles was evaluated along with the uninoculated control and pathogen inoculated control and the green CuNPs synthesized using leaf extracts of cinnamon was noticed with highest shelf life (9 days) and excellent organoleptic properties followed by green CuNPs synthesized using leaf extracts of clove (8 days) and cinnamon oil NE (7 days). Based on the results of in vivo evaluation, the best three treatments (Green CuNPS synthesized using leaf extracts of cinnamon, clove and cinnamon oil NE) were taken for the study of biochemical changes (Reducing sugar, ascorbic acid, titratable acidity, protein, moisture and pH) in comparison with the uninoculated control and pathogen inoculated control. The green CuNPs synthesized using leaf extracts of cinnamon was noticed with less biochemical changes with a decrease in reducing sugar (8.30 %), decrease in ascorbic acid (62.56 mg/100g), decrease in titratable acidity (0.59 %), decrease in protein (5.08 mg/g fresh weight), increase in moisture (56.24 %) and acidic in pH (3.40) when compared with the uninoculated control with reducing sugar (8.87 %), ascorbic acid (62.77 mg/100g), titratable acidity (0.60 %), protein (5.25 mg/g fresh weight), moisture (55.88 %) and pH (3.41) followed by green CuNPs synthesized using leaf extracts of clove and cinnamon oil NE. The present study revealed that the major pathogen associated with anthracnose of banana fruits is Colletotrichum musae. The postharvest spraying of green CuNPs synthesized using leaf extracts of cinnamon at 0.05 % is proved to be an effective novel strategy for the management of banana anthracnose with higher shelf life (9 days) and excellent organoleptic properties. The results may be subjected to multi-location and multi seasonal field trials and the residual toxicity of CuNPs on the fruits have to be undertaken.Item Plant defense activators for the management of leaf blight of amaranthus (amaranthus sp.L)(Department of plant pathology, college of agriculture, Padannakkad, 2023-11-23) Athul Manoj; Sajeesh, P KThe present study entitled “Plant defense activators for the management of leaf blight of amaranthus (Amaranthus sp. L.)” was conducted in the Department of Plant Pathology, College of Agriculture, Padannakkad during 2021-2023. A purposive sampling survey was conducted in Agro Ecological Unit II (AEU II). Amaranthus plants exhibiting leaf blight symptoms were collected from the Instructional Farm, College of Agriculture, Padannakkad and also from farmers’ fields in AEU II. Among the six locations surveyed, percent disease incidence (PDI) and percent disease severity (PDS) showed a range of 32 to 71 per cent and 27 to 58 per cent respectively. Six isolates of the fungus associated with leaf blight of amaranthus were obtained and were denoted as Rs1, Rs2, Rs3, Rs4, Rs5 and Rs6. Pathogenicity was proved for all the six isolates. Among the six isolates, Rs2 developed leaf blight symptoms within two days after artificial inoculation along with highest lesion size when compared to other isolates. Hence Rs2 was selected as the most virulent isolate and used for further studies. The isolate Rs2 was identified with it’s cultural, morphological and molecular characteristics and was confirmed as Rhizoctonia solani. All the remaining isolates exhibited cultural and morphological characters exactly similar to that of isolate Rs2. In the second part of this study, the efficacy of a category of novel chemicals known as plant defense activators against R. solani was tested. In vitro screening was conducted to evaluate the antifungal activity of plant defense activators such as two seaweed extracts and chitosan at different concentrations using the poisoned food technique with 11 treatments and three replication using CRD. Ascophyllum nodosum extract (ANE) at a concentration of 7500 ppm (T2) exhibited the highest inhibition of mycelial growth of the pathogen (39.40 %). The plant defense activators were short-listed based on their efficacy under in vitro evaluation and the effectiveness of selected treatments against the disease was assessed by pot culture experiment. Two separate experiments were carried out with pre-inoculation and post-inoculation of R. solani each with eight treatments and three replication using CRD. After a week of inoculation, the least per cent lesion development (34.22 %), as well as the lesion size (2.51 cm2), was recorded in the treatment ANE (7500 ppm) (T2) with post-inoculation of the pathogen. However, based on efficacy in pot culture experiment five treatments were selected for field evaluation. A field experiment with six treatments and four replication using RBD was laid out during May- July 2023 in the Instructional Farm, College of Agriculture, Padannakkad. Natural incidence of the disease was noticed after 15 days of transplanting (DAT). Hence the treatments were given as foliar spray at 15, 30 and 45 DAT. ANE (7500 ppm) (T2) and Phaeophycean seaweed extract (PSWE) (7500 ppm) (T1) recorded least PDI of 40 per cent and 45 per cent respectively. At the same time, absolute control (T6) and turmeric powder + baking soda (5:1) (T5) recorded PDI of 60 and 55 per cent respectively. Significant reduction in number of lesions, lesion size and PDS were observed after the use of different plant defense activators. ANE (7500 ppm) (T2) was superior to all treatments in reducing the disease which recorded the least number of lesions (38.4), lesion size (2.84 cm2) and PDS 44.60 per cent. In addition to disease reduction, ANE (7500 ppm) (T2) recorded significant growth promotion in amaranthus plants. It recorded the highest number of leaves (66), shoot and root length (114.95 and 24.5 cm), shoot and root biomass on fresh weight basis (13475 and 7547.5 kgha-1) and dry weight basis (5650 and 2420 kgha-1). Further in the study, the biochemical basis of disease reduction was elucidated by estimation of defense related enzymes. Polyphenol oxidase (PPO) activity was increased in the treatment ANE (7500 ppm) (T2) from 1.46 to 1.88 ΔA/mg/min. Plants that were treated with the ANE (7500 ppm) (T2) exhibited elevated peroxidase (PO) activity of 6.78 μg g-1 fw 7 days after treatment. After pathogen infection, a significant increase in catalase (CAT) activity and elevated level of phenyl alanine ammonia lyase (PAL) activity was recorded in (T2). The present study revealed that ANE (7500 ppm) (T2) a seaweed extract has remarkable inhibitory activity against R. solani and is effective in managing leaf blight disease of amaranthus by the induction of host defense enzymes. Moreover, it enhances plant growth and biomass production in amaranthus. The signalling pathways associated with defense induction and growth promotion activity by plant defense activators have to be investigated further.Item Biopriming and foliar apllication of biocontrol agents and endophytes for the management of major foliar fungal diseases of bush cowpea(Department of Plant Pathology, College of Agriculture , Vellayani, 2023-05-26) Aswathy ,V S.; Radhakrishnan, N VThe study entitled “Biopriming and foliar application of biocontrol agents and endophytes for the management of major foliar fungal diseases of bush cowpea” was conducted at College of Agriculture, Vellayani and Coconut Research Station, Balaramapuram during 2020-2022. The objective was to develop best ecofriendly management practice involving biopriming, foliar application of endophytes and biocontrol agents for the control of major foliar fungal diseases in bush cowpea with special emphasis on Cercospora leaf spot and anthracnose. Symptomatology and etiology of anthracnose and Cercospora leaf spot were studied under field condition from different locations in Trivandrum district viz., Vellayani, Pappanchani, Venganoor, Balaramapuram, Nedumangad and Parassala. The pathogens were isolated and studied their morphological characteristics. Bush cowpea seeds were collected from five agro-ecological zones of Kerala viz., Northern, High range, Central, Special problem and Southern zones and the seeds were assessed for both externally and internally seed borne microflora. Percentage of infection was calculated by blotter method. The lowest percentage of infection was found in seed samples collected from Wayanad (16.7%) and the highest in Thrissur (38.2%). The diseased leaf samples showing anthracnose were collected from five locations of Thiruvananthapuram district and isolated Colletotrichum gloeosporioides from each location. Pathogenecity of isolated pathogen was proved by detached leaf assay and seedling assay. Vellayani isolate (C1) was found to be the most virulent pathogen and recorded lesion size of 4.33cm and 1.82cm in detached leaf assay and seedling assay on seventh day respectively. The isolate C1 was used for further studies. In vitro evaluation of biocontrol agents like Trichoderma asperellum T6 (KAU), Trichoderma koningiopsis (TRKR2), Trichoderma harzianum (TRMW2), Piriformospora indica (No. INBA 3202001787), Bacillus amyloliquiefaciens VLY 24, Bacillus velezensis (CBRE5), Bacillus amyloliquefaciens (CBSE5) and Pseudomonas fluorescens PN026 (KAU isolate) against Colletotrichum gloeosporioides and Cercospora sp. were carried out. Dual culture method of Colletotrichum gloeosporioides against biocontrol agent recorded highest percentage inhibition of mycelia by T. asperellum (64.76) followed by Trichoderma strain TRKR2 (52.63) which was on par with bacterial strain CBRE5 and least for Psuedomonas fluorescens. In vitro pathogen suppression by spore germination assay on Cercospora sp. by 145 biocontrol agents revealed that maximum inhibition of conidia germination was by T. asperellum (36.25 %) followed by Trichoderma strain TRKR2 and Trichoderma strain TRMW2 whereas least inhibition percentage was observed with Piriformospora indica (14.96). Peroxidase and polyphenol oxidase assay on bush cowpea pods and seeds showed that fungus infected tissues had relatively higher activity of these oxidase enzymes in comparison to healthy pods. Enzyme activities were higher in pods and seeds treated with Bacillus strain CBRE5, T. asperellum and Trichoderma strain TRKR2. Standardization of priming techniques revealed that soaking of seeds for 2h was found effective for Trichoderma asperellum, Bacillus velezensis (CBRE5) and Bacillus amyloliquiefaciens VLY 24 and 4h for Trichoderma strain TRKR2. The soaking duration is followed for the treatments in in vivo studies. Based on the in vitro studies, the best three treatments viz., Trichoderma asperellum, Trichoderma strain TRKR2 and Bacillus strain CBRE5 were taken for in vivo studies. In vivo studies on the effect of seed biopriming and spraying of biocontrol agent suspension at 4 leaf, 50 per cent, flowering and pod set stages revealed lowest disease severity of anthracnose was recorded for Trichoderma asperellum treated plants with disease suppression over control 41.74 per cent followed by carbendazim, Trichoderma strain TRKR2 and Bacillus strain CBRE5. In the case of Cercospora leaf spot Trichoderma asperellum treated plants shown highest disease suppression (63.47%) over control followed by carbendazim, Trichoderma strain TRKR2 and Bacillus strain CBRE5. Bacillus strain CBRE5 recorded least disease suppression over control in anthracnose and Cercospora leaf spot while comparing other treatments. Highest number of pods per plant (34.75), seeds per pod (15.25), plant height (46.05 cm) and yield (232.47 g) were shown by bacterial strain CBRE5 treated plants. Thus, the present study indicated that the seed biopriming for 2 h along with foliar application of Trichoderma asperellum suspension at 4 leaf , 50 per cent flowering and pod set stages was most effective treatment for the management of major foliar fungal diseases like anthracnose and Cercospora leaf spot of bush cowpea whereas seed biopriming for 2 h along with foliar application of Bacillus velezensis suspension at 4 leaf stage, 50 per cent flowering stage and pod set was the best treatment in plant growth promotion in vivo which could be used as an eco-friendly measure to produce safe to eat crop.Item Cataloguing and characterization of diseases of ornamental foliage plants in Kerala(Department of Plant Pathology, College of Agriculture, Vellanikkara, 2023-06-23) Sandra, S R.; Gleena Mary ,C FOrnamental foliage plants are globally recognised for their brilliant colours, texture, patterns and foliar variegations. They are widely used as an integral component in indoor as well as outdoor gardening and adapt well under low light conditions. The common ornamental foliage plants like Dracaena, Aglaonema and Philodendron have tremendous potential and marketability in the domestic as well as international market which is drastically reduced by different diseases occurring on their foliage. Hence the present study was undertaken to identify various diseases of Dracaena, Aglaonema and Philodendron plants cultivated in Kerala and the pathogens associated with these diseases. A purposive sampling survey was undertaken in ornamental foliage growing areas and commercial nurseries of Wayanad, Malappuram, Thrissur, Ernakulam and Thiruvananthapuram districts representing the Northern, Central and Southern zones of Kerala. From the 11 different survey locations, 18 diseased Dracaena samples, 10 Aglaonema samples and 10 Philodendron samples were collected. Leaf blight and leaf spot were the prominent symptoms observed in these survey locations. The collected samples consisted of 17 leaf blight samples of Dracaena, eight leaf blight samples of Aglaonema and seven leaf blight samples of Philodendron and the leaf spot samples of Dracaena, Aglaonema and Philodendron collected were one, two and three respectively. Among the leaf blights of Dracaena, the sample M Kr DLB2 recorded the highest per cent disease incidence (PDI) and per cent disease severity (PDS) values of 85.00 and 72.22 per cent respectively. The sample, E Ka DLS1 was the only Dracaena leaf spot sample with PDI 18.18 per cent and PDS of 16.66 per cent. Among the Aglaonema samples collected, the leaf blight sample, T Vk ALB2 recorded the highest PDI (37.50 %) and PDS values (20.62 %) and leaf spot sample, E Am ALS2 recorded highest PDI (20.00 %) and PDS (4.51 %). T Vk PLB1 was the Philodendron leaf blight sample with maximum PDI (22.77 %) and PDS (40.00 %). Among the leaf spot samples of Philodendron, severe one was TV Ko PLS1 which recorded PDI of 37.50 and PDS of 7.83 per cent. Isolation and pathogenicity studies resulted in 21 fungal isolates from Dracaena, 13 from Aglaonema and 10 isolates from Philodendron samples. The symptoms associated with these pathogens were studied both under natural as well as under artificial conditions. Genus level identification of each pathogen was carried out on the basis of cultural and morphological characteristics. Based on this the fungal pathogens of Dracaena were identified as Colletotrichum spp. (9 nos.), Fusarium spp. (4 nos.), Lasiodiplodia spp. (3 nos.), Phomopsis spp. (2 nos.) and Neopestalotiopsis sp. The fungal pathogens of Aglaonema were identified as Colletotrichum spp. (7 nos.), Fusarium spp. (2 nos.), Pestalotiopsis sp., Curvularia sp. and Corynespora sp. The pathogenic fungi associated with diseased Philodendron samples were Colletotrichum spp. (8 nos.), Fusarium sp. and Phytophthora sp. Molecular characterization of 13 selected fungal pathogens was attempted by analysing the amplified LSU or ITS sequences of pathogens with NCBI BLASTn database. Based on this the fungal pathogens of Dracaena were Colletotrichum gloeosporioides (Glomerella cingulata) (M Kr DF2), Fusarium oxysporum (M Kr DF4), Diaporthe tulliensis (Phomopsis heveicola) (T Th DF3), Lasiodiplodia theobromae (E Ka DF1) and Neopestalotiopsis aotearoa (TV Vy DF2). The fungal pathogens of Aglaonema, M Ch AF1, T Vk AF2, E Am AF1, E Am AF3 and E Am AF4 were identified upto species level as Pestalotiopsis microspora, Colletotrichum gloeosporioides, Curvularia clavata, Fusarium oxysporum and Corynespora smithii respectively. The result of in silico analysis revealed the fungal isolates of Philodendron spp. T Vk PF1identified as Colletotrichum dracaenophilum, E Am PF3 as Fusarium incarnatum and TV Pu PF1 as Phytophthora nicotianae. Host range studies of 11 fungal pathogens of Dracaena (Colletotrichum spp., Fusarium spp., Neopestalotiopsis sp., Phomopsis spp. and Lasiodiplodia sp.) were carried out on rubber, coconut, nutmeg and banana. All the pathogens produced characteristic symptoms on the detached healthy leaves of the host plants within 1 to 4 days of inoculation except on banana leaves, in which the Colletotrichum spp. (M Kr DF2, T Th DF2, E Ka DF2 and TV Pu DF2) failed to produce any lesions on the inoculated leaves. The in vitro studies using chemical fungicides and biocontrol agents were performed against the 13 selected fungal pathogens of Dracaena, Aglaonema and Philodendron. Mancozeb was the most effective contact fungicide with a per cent inhibition ranging from 77.78 to 100 per cent against all the tested pathogens. Tebuconazole was found most effective systemic fungicide with complete inhibition of the growth of all pathogens. Among the combination fungicides, carbendazim 12% + mancozeb 64% recorded the highest efficiency with complete control of all pathogens at all tested dosages. In vitro studies with different biocontrol agents against selected fungal pathogens revealed PGPM as the most effective with 72.77 to 100 per cent inhibition followed by Trichoderma asperellum (36.66 - 100 %) and PGPR (33.33 - 100 %). The bacterial antagonist, Pseudomonas fluorescens showed the lowest inhibition with a per cent inhibition of 0 to 20.55 per cent. It may be concluded that the present study has enlightened our knowledge of devastating diseases of common ornamental foliage plants cultivated in Kerala viz., Dracaena spp., Aglaonema spp. and Philodendron spp. and also on disease management aspects of the associated pathogens.