Browsing by Author "Gokulapalan, C"

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Biology and cultivation of ganoderma spp.
(Department of Plant Pathology, College of Agriculture, Vellayani, 2013) Vineeth V Varma; Gokulapalan, C
Ecofriendly management of collar rot and web blight of cowpea
(Department of Plant Pathology, College of Agriculture, Vellayani, 2007) Bhadra Sree, S; Gokulapalan, C
The study “Ecofriendly management of collar rot and web blight of cowpea was conducted at the Department of Plant Pathology, College of Agriculture, Vellayani during 2004-2007. Different plant oils, oil cakes, indigenous materials like turmeric power – baking soda and rice husk ash and biocontrol agents like Trichoderma harzianum and Pseudomonas fluorescens were used in the study to manage R. solani causing the disease. Among the seven plant oils tested odal and pongamia oil emerged as the most potential ones. Of the four oil cakes gingelly and coconut cakes were identified as the best treatments. The different combinations of turmeric powder – baking soda and rice husk ash did not inhibit the growth of R. solani. Pot culture experiments were conducted to assess the efficacy of plant oils, oil cakes, biocontrol agents and indigenous materials in enhancing the growth of cowpea. Both the plant oils used in the study were successful in managing the disease. Of the three oil cakes used in the study gingelly cake exhibited best performance in disease management and growth enhancement. Of the indigenous materials used 10:1 combination of turmeric powder – baking soda and 1000gm-2 concentration of RHA were found to be excellent in enhancing growth and disease suppression. Biocontrol agents T. harzianum and P-22 culture of P. fluorescens were found to be superior in disease suppression and growth enhancement. Changes in levels of total phenols, proteins, carbohydrates and activities of defense related enzymes like PO, PPO and PAL due to above treatments were estimated. The treatment 10:1 ratio of turmeric powder – baking soda recorded highest protein and PO content. Soil application of oil cakes gave increased activity of PAL and carbohydrate.
Ecofriendly management of rhizoctonia leaf blight of amaranthus
(Department of Plant Pathology, College of Agriculture, Vellayani, 2003) Priyadarsini, P; Gokulapalan, C
The present investigation was undertaken at College of Agriculture, Vellayani during the year 2002-2003 to evolve an ecofriendly practice for the management of foliar blight of amaranthus caused by Rhizoctonia so/ani. Biocontrol agents like Trichoderma harzianum, Pseudomonas jluorescens, a newly discovered root endophyte, Piriformospora indica and indigenous materials like turmeric powder-baking soda and rice husk ash were used in the study. From among the ten isolates of R. so/ani, the isolate R3 (Vellayani) which produced maximum disease symptoms W?3 selected for the study. Among the four fungal antagonists tested against R. so/ani, T. harzianum emerged as the most potential one. The fungus, P. indica when subjected to dual culture with R. so/ani did not cause any inhibition on its growth. Among the four isolates of P. jluorescens tested against R. so/ani, the isolate B3 showed maximum inhibition followed by the isolate KK16. The culture filtrate of the isolate of P. jluorescens viz., B3 alone exerted inhibitory effect on the growth of R. so/ani. The different combinations of turmeric powder-baking soda and rice husk ash did not inhibit the growth of R. so/ani . . ' Pot culture experiments were conducted to assess the efficacy of biocontrol agents and indigenous materials in managing the disease and enhancing the growth of amaranthus. Among the three concentrations of rice husk ash used, the highest concentration of 1000 g produced maximum disease suppression and enhancement of growth. Rice husk ash exerted significant effects on all the growth parameters. The fungal antagonist T. harzianum and bacterial isolates B3 and KK16 were found to be highly effective in reducing the disease and enhancing growth. 10 : I combination of turmeric powder-baking soda was found to enhance the growth significantly and there was a reduction in the disease incidence also. The highest concentration of P. indica (2.00 per cent) recorded the maximum root colonization and exerted significant effects on root length and root dry weight. Changes in the level of total phenols, amino acids carbohydrates and enzymes like PAL, PO and PPO due to the above treatments were estimated. Soil application followed by foliar spray of fungal and bacterial antagonists significantly enhanced the activity of the defense related enzymes. The level of total phenol was found to be higher for plants treated with T. harzianum. There was no significant increase in amino acid and carbohydrate content due to these treatments. The results of this study indicate that the efficient strains of T. harzianum and P. fluorescens (soil or foliar application) can be used in tandem with rice husk ash to evolve a suitable ecofriendly disease management strategy to combat foliar blight of amaranthus.
Effect of plant protection chemicals on foliar pathogens and Phylloplane microflora of rice
(Department of Plant Pathology, College of Agriculture, Vellayani, 1989) Gokulapalan, C; Chandrasekharan Nair, M
The present investigation was undertaken to assess the effects of plant protection chemicals on the important fungal pathogens and phylloplane microflora of rice. An attempt has been made to identify potential biological control agents to combat sheath blight disease causing havoc to rice cultivation in Kerala. Both under pot culture conditions and during the course of field trials at two locations viz., Adoor and Karamana, Kerala, the fungicide carboxin was found to be the best treatment for reducing the incidence and intensity of sheath blight and sheath rot diseases of rice. The fungicide was found to be the least harmful to the epiphytic microflora of the rice plant. In some instances the population of phylloplane antagonists of R. solani, including Trichoderma harzianum, T. viride, Penicillium oxalicum and Aspergillus aculeatus were found to be enhanced by the application of carboxin. The total disease incidence and yield loss were significantly reduced by the application of edifenphos. The rice variety Karthika was found to be significantly tolerant to sheath blight and sheath rot compared with the rice variety Jyothy. The fungicides carboxin and mancozeb at 500ppm did not inhibit the growth of the phylloplane antagonists of R. solani viz., Trichoderma harzianum and T. viride under in vitro conditions. Several micro-organisms isolated from the rice phylloplane were found to exhibit in vitro antagonism towards R. solani. These include Aspergillus aculeatus, A. niger, Chaetomium globosum, Penicillium oxalicum, Trichodema harzianum, T. viride, several bacteria and a few basidiomycetous yeasts. The phylloplane antagonists, Trichoderma harzianum, T. viride and Penicillium oxalicum were found to readily parasitise R. solani hyphae leading to coiling, penetration followed by disintegration and death of the mycohost. When these antagonists were cultured on bran and tried for their efficacy as potential biocontrol agents of R. solani, it was found that these fungi could significantly reduce the incidence and intensity of sheath blight of rice, though this was not comparable with the effect of the fungicide carboxin.
Epidemiology and management of false smut of rice (Oryza sativa L) in Kerala
(Department of Plant Pathology, College of Agriculture, Vellayani, 2014) Rashmi, C R; Gokulapalan, C
Integrated management of anthracnose in chilli (Capsicum annuum L.)
(Department of Plant Pathology, College of Agriculture, Vellayani, 2015) Shilpa Treasa Chacko; Gokulapalan, C
The study entitled “Integrated management of anthracnose in chilli (Capsicum annuum L.)” was conducted at Department of Plant Pathology, College of Agriculture, Vellayani, Thiruvanathapuram during 2013-2015 with the objective to evolve an integrated management package for anthracnose in chilli. Nine isolates of the pathogen causing chilli anthracnose were isolated and based on morphological characters like colony colour, conidial shape and dimensions, the pathogens causing fruit rot disease of chilli were identified as Colletotrichum capsici (Syd.) Butler and Bisby and Colletotrichum gloeosporioides (Penz.) Penz. and Sacc. which was further confirmed and deposited at Agharkar Research Institute, Pune with accession number NFCCI- 3411 & NFCCI- 3412, respectively. Pathogenicity was proven following Koch’s postulates and virulence rating was done. From this the most virulent isolate C2, an isolate of C. capsici was selected for the further studies. The results of standard blotter test and standard agar plate method revealed that C. capsici and C.gloeosporiodes infection in chilli is seed borne in nature. The results also indicated the dominance of C. capsici (44.66 per cent) followed by C. gloeosporioides (12.00 per cent), Alternaria sp. (0.50 per cent). Saprophytic fungi recorded were Penicillium sp. (0.16 per cent) and Aspergillus sp. (0.16 per cent). The study showed that C. capsici survived for 77 days in the infected fruits and leaves in the soil and 42 days in the lab condition. The host range studies revealed that the solanaceous crops brinjal (Solanum melongena L.) and tomato (Solanum lycopersicum L.) at fruiting stage were found to be alternative hosts of C. capsici under natural conditions. However on artificial inoculation of C. capsici, brown lesions were observed on leaves of green gram (Vigna radiata L.), ivy gourd (Coccinia indica L.), sesame (Sesamum indica L.), black gram (Vigna mungo L.) and sweet potato (Ipomoea batatus L.). Natural incidence of disease was observed on weeds Richardia scabra L. (Tropical girdlepod) and Commelina benghalensis L. (Tropical spiderwort). The predominant micro-organisms isolated from chilli phyllosphere, pomoplane and rhizosphere Penicillium citrinum, Trichoderma viride, Bacillus and Pseudomonas flourescens exhibited 56.23 per cent, 64.45 per cent, 88.88 per cent and 73.33 per cent inhibition of the pathogen respectively under in vitro conditions. In vitro assay of fungicides with poisoned food technique revealed that propiconazole (0.15 per cent), difenoconazole (0.05 per cent) and mancozeb (0.2 per cent) completely inhibited the mycelial growth of C. capsici. It was followed by azoxystrobin (0.15 per cent), captan+hexaconazole (0.1 per cent), carbendazim (0.1 per cent) with mycelial inhibition of 97.77 per cent, 88.30 per cent and 83.33 per cent respectively. No mycelial growth of the pathogen was observed in chlorothalonil (0.1 per cent) amended media. Among organic preparations, panchagavya provided complete inhibition of the growth of the pathogen at all the concentrations tested. Jeevamruth provided complete inhibition only at 10 per cent concentration, whereas, the amendment of media with fish amino acid did not affect the mycelial growth of the pathogen. Chilli seedling assay of different bioagents for the control of disease on seedlings revealed that the percentage seedling mortality was lowest for the seeds treated with the biocontrol bacterium Bacillus sp. (10.46 per cent) isolated from phyllosphere and pomoplane followed by the KAU released biocontrol agent Pseudomonas flourescens (15.36 per cent). Piriformospora indica treated seeds exhibited 45.36 per cent mortality.Seedling assay with fungicides revealed that seeds treated with propiconazole (0.1 per cent) exhibited the lowest seedling mortality (10.37 per cent). A pot culture study conducted with chilli variety Vellayani Athulya to evaluate the efficacy of organic preparations, biocontrol agents and fungicides and it revealed that maximum disease suppression was provided by foliar spraying of 0.1 per cent propiconazole (62.85 per cent) and 0.05 per cent difenoconazole (61.06 per cent) at fortnightly intervals. Among the biocontrol agents, Bacillus sp. was found to be superior in suppressing the disease (59.59 per cent) and among organic preparations, panchagavya gave the maximum suppression of the disease (57.06 per cent). Based on the results of the study, an integrated management package for anthracnose in chilli is proposed as follows: Seed treatment with systemic fungicides like propiconazole (1 ml kg-1) or biocontrol agents like Pseudomonas fluorescens 10 g kg-1 prevent seed borne infection , removing infected crop debris and destroying alternative hosts such as tomato, brinjal, green gram, black gram, sesamum, ivy gourd and sweet potato and weed hosts such as Richardia scabra and Commelina benghalensis prevent disease incidence and foliar spraying of propiconazole (1 ml l-1) or difenoconazole (0.5 ml l-1) or panchagavya (2.5 ml l-1) at fortnightly intervals after the onset of the disease controls the disease.
Integrated mangement of pythium stem rot of vegetable cowpea (Vigna unguiculata sub.sp.sesquipedalis (L) Verdcourt
(Department of Plant Pathology, College of Agriculture, Vellayani, 2014) Mohammed Anees, M; Gokulapalan, C
Leaf blight of Dioscorea Esculenta (Lourd.) Berk.
(Kerala Agricultural University, 1980) Chandrasekharan Nair, M; Karunakaran, P; Gokulapalan, C
Mycoflora associated with leaf litter decomposition in homesteads
(Department of Plant Pathology, College of Agriculture, Vellayani, 1996) Jannet Daniel; Gokulapalan, C
Fungi play an inevitable role in the biodegradion of leaf litter. The present investigation was carried out to assess the role of mycoflora in the degradation of jack and mango in the identified homestead. Many litter decomposing fungi were isolated from both jack and mango leaf litter. The period of study was during September 1993 to March 1995. Nine genera of fungi were frequently isolated from mango leaf litter of which eight belonged to Deuteromycotina, and one to Zygomycotina. Thirteen genera of fungi were frequently isolated from jack leaf litter at different stages of decomposition, of which twelve belonged to Deuteromycotina and one to Zygomycotina. The common primary colonizers isolated were Aspergillus niger, A. flavus, Penicillium citrinum, P. oxalicum, P. islandicum, Pestalotia palmarum, Colletotrichum gloeosporioides, Trichoderma viride and T. harzianum. The common fungi isolated from decomposing leaf litter of both trees were Mucor hiemalis. Members of Basidiomycotina were also isolated from decomposing leaf litter. At higher temperature the fungal counts were lower in the fresh litter but higher in decomposed leaf litter of both trees. At higher rainfall the fungal count was more in surface litter but the same was lower in decomposed leaf litter. Identification and description of 30 fungal species were carried out following slide culture technique. The weight loss was more at 450C, when compared with weight loss at 350C and 250C of both mango and jack leaf litter. The weight loss was more pronounced in the field condition as against laboratory conditions. Higher temperature and higher rainfall led to an increased rate of litter decomposition. The decay process was faster in jack indicating the higher efficiency of decomposition in the case of jack litter as compared with mango. The decomposition constant (K) for jack was 1.52 as against a lower K value of 1.03 for mango. This indicates the faster decomposition of jack leaf liter when compared with mango litter. Trichoderma viride, Trichoderma harzianum, Chaetomium globosum, Verticillium theobromae, aspergillis niger, A. ochraceous, A. tamari, Penicillium oxalicum were found to be efficient in utilizing cellulose as their sole carbon source. There was an increase in nitrogen and ash content in the decomposing leaf litter when compared with fresh litter. The carbohydrate content was more in fresh litter and the same decreased with the progress of decomposition. Inoculation studies with common plant pathogens isolated from jack and mango leaf litter were done and Colletotrichum gloeosporioides was found to infect mango and jack leaf litter producing characteristic symptoms on mango and jack.
New leaf and flower blight of Anthurium Andreanum Lind
(Kerala Agricultural University, 1997) Naseema, A; Kamala Nayar; Gokulapalan, C
Role of the rice root nematode (Hirschmanniella oryzae) in the incidence of sheath blight disease of rice in Kerala
(Department of Plant Pathology, College of Agriculture, Vellayani, 1981) Gokulapalan, C; Chandrasekharan Nair, M
Rhizoctonia solani causing sheath blight of rice was found to infect a number of common weeds and crops raised in rice fallows in Kerala. The fungus was found to produce leaf and stem blight in groundnut plants. This is the first report of this fungus causing serial blight symptoms in adult groundnut palnts. On Sesbania aculeata (daincha), the fungus produce severe collar rot, this being the first record of this fungus on this crop in India. The occurrence of R.solani under natural conditions on the weeds, Anluda aristata and Monochoria vaginalis are reported for the first time.