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ThesisItem Open Access Management of foot rot of black pepper (Piper nigrum L.) with mycoinoculant enriched vermicompost(Department of Plant Pathology, College of Agriculture, Vellayani, 2002) Divya, S; Sasikumar NairThe study, "Management of foot rot of black pepper (Piper nigrum L.) with mycoinoculant enriched vermicompost" was done at the Department of Plant Pathology, College of Agriculture, Veliayani to explore the possibility of using vermicornpost as a carrier material for mass production of biocontrol agents and to test its efficacy in controlling the disease. The talc based inoculum of Trichoderma harzianum and soil based granular inoculum of Glomus Jasciculatum were mass produced in vermicompost either alone or in combination with farmyard manure or neem cake in the ratio 1 : 1 and 5 : 1 respectively and the efficacy was compared with the standard carrier material of FYM + neem cake (10 : 1). The population of T. harzianum 15 DAI was maximum in the treatment combination of VC + NC (5 : 1). However, the influence of these carrier materials on percentage of mycorrhizal infection 50 DAI was not statistically significant. Vermicompost as a carrier material for biocontrol agents was further tested in pepper var. Karimunda inoculated with P. capsici. Carrier materials as such had no significant influence on disease control. Reduction in foliar infection, disease index, stem infection and percentage mortality was observed in treatments with biocontrol agents. Disease control was maximum with the treatments involving T. harzianum while plant growth promotion was maximum with G. Jasciculatum. The physiological changes in pepper plants after inoculation with P. capsici and biocontrol agents were studied. The phenol and OD phenol content was more in pathogen inoculated plants. The defence related enzymes peroxidase, polyphenol oxidase and phenylalanine ammonia lyase were enhanced with pathogen inoculation as well as with the application of biocontrol agents. SDS-PAGE analysis of proteins with samples extracted from plants one day after inoculation of pathogen showed the presence of two novel proteins with molecular . weights of 78 kDa and 28 kDa in diseased samples which were absent in treatments without pathogen and also in plants treated with COC.ThesisItem Open Access Management of bacterial blight of anthurium (anthurium andreanum linden) using botanicals(Department of Plant Pathology, College of Agriculture, Vellayani, 2002) Sabitha, S R; KAU; Mary, C AAnthurium (Anthurium andreanum Linden) suffers from a serIOUS disease viz., bacterial blight incited by Xanthomonas axonopodis pv. diefJenbachiae (McCulloch and Pirone) Vauterin et al. A survey was conducted in Thiruvananthapuram district and information on disease intensity and varietal reaction of the disease was studied from randomly selected thirty anthurium gardens. Plants with disease infection upto 50 per cent was noticed in most of the gardens. Generally pink varieties exhibited tolerance while red varieties were susceptible. Both foliar and systemic symptoms were observed. The bacterium was a gram negative, motile, short rod. Potato Sucrose Agar was the best solid medium for growth of the bacterium. Morphological, physiological and biochemical characters of the ten isolates were compared and some characters like nature and rate of growth, virulence and hydrolysis of starch were found varying. Aglaonema sp., Alocasia sanderiana, Anthurium ornatum, Colocasia esculenta, Dieffenbachia spp., Philodendron spp., Syngonium sp. and Xanthosoma sagittaefolium of Araceae family and ornamental plants like Orchid spp., Dracaena spp. Heliconia sp., Sterilitzia reginae and Maranta arundinaceae were hosts of the pathogen. Among the fifteen botanicals tested under in vitro conditions crude extract and 2 : 1 dilution of Allium sativum and Tagetes erecta, crude and two per cent concentration of neem cake extract and one and two per cent neem oil and coconut oil were 'effective in inhibiting the growth of the pathogen. The relative efficacy of five ecofriendly management practices viz., application of A. sativum, T. erecta, neem oil, coconut oil and neem cake extract, at two levels and 100 ppm streptocycline were tested on seven month old tissue culture plants. Pre and post inoculation sprayings with crude extract of neem cake and T. erecta reduced the disease by 85 per cent. When the same spraying schedule with these two botanicals and 100 ppm streptocycline was given on flowering plants, crude extract of neem cake was the most effective followed by crude extract of T. erecta. The effect of streptocycline 100 ppm was on par with T. erecta. The study thus indicates that botanicals could be used as a substitute for antibiotics in the management of bacterial blight of anthurium.ThesisItem Open Access Integrated management of leaf rot of coconut(Department of Plant Pathology, College of Agriculture, Vellayani, 2002) Vrinda, T S; Joseph, P JThe study entitled as "Integrated management of leaf rot of coconut" w as conducted at the Department of Plant Pathology, Co l.cge of Agr iculturc. Ve l l a van i and Iie ld trial was conducted at RARS. Kumarakorn. Extensive iso lai io n s. pathogenicity and characterization studies of the pathogens assoc i aic d with leaf rot infected spindle leaf of coconut from di ffercnt r e g ions 0 I' f ve southern districts of Kerala revealed that Collct otrichu m g/oco.,porioidcs. Fusarium so/ani, Fusarium. monil if..rniae, Fusari utn oxvsp or utn, Cephalosporium sacchari. Exserohilum rostrat um. Gl iocl adi um roselllll.<';C\!o!idillll7 sp. and Curv ular i a sp. played ct io lo gj 0" LRD. Based on frequency 01' isolarions. Fusarium spp. .ind C .g/()(;o.,porioides Viere identified as major pathogens or LRD in these areas. The present study constitutes the first report or the ct io log ica l ro l c of Scvt ul uliurn ::;0 in leaf rot incidence. Symptomatology of the disease based on natural incidence in the I'dd and upon artificial inoculation were clearly described The in vit ro interactions of different dual combinations of LRD pathogens were found to be predominantly associative rather than inhibitory in nature. The rapid lesion development of certain dual combinations of the pathogens upon artificial inoculation further signified the associative nature of these pathogens. Extensive in vi/m screening and leaf bit assay of different antagonistic microorganism identified T9 culture of Trichoderma sp. PSI culture of Pse u domonasfluorescens as two potential agents against i he major pathogens of LRD. The in vitro interactions study of the selected fungal and bacterial antagonist showed that both are incompatible and hence unsuitable for combined delivery. Bioassay results showed that fungicides hcxaconazo lc and propiconazole completely inhibited the growth of C. gloeosporioides. E. rostra/um and F. solani while mancozeb was more effective at higher concentrations. one of the fungicides was inhibitory to P. j7uorescens while Trichoderma sp. was inhibited by hex aconazo!e and hence the fungal antagonist was unsuitable for combined delivery with the fungicides. Evaluation of different components of disease management indicated that phytosanitation coupled with hexaconazole application was effective in reducing disease severity of leaf rot in the field.ThesisItem Open Access Exploitation of hypovirulence in Rhizoctonia solani kuhn for Management of sheath blight in rice(Department of Plant Pathology, College of Agriculture, Vellayani, 2001) Ranjit, A; KAU; Girija, A KA study was conducted at Department of Plant Pathology, College of Agriculture, Vellayani to explore the variability in Rhizoctonia so/ani with a view to detect hypoviruient strains of the fungus, and evaluate the efficacy of these isolates in management of sheath blight disease of rice. Six hypovirulent isolates were selected after screerung 28 isolates obtained from different rice growing tracts of Kerala. Screening for hypovirulence was . based on cultural characters like mycelial growth rate and sclerotial production under ill vitro conditions, and pathogenicity tests through cut stalk assay. The hypovirulent isolates were non-sclerotial whereas the virulent isolate produced profuse sclerotia. The hypovirulent isolates produced tan mycelia appressed to the medium In Petri dishes. Antibiosis and hyperparasitism were absent in the interaction between the hypovirulent and virulent isolates in vitro. The character of hypovirulence could not be transmitted from hypovirulent to the virulent isolate. The hypovirulent isolates had no effect on the germination and seedling vigour of rice plants. They did not produce symptoms of sheath blight on susceptible variety. Two of the six hypovirulent isolates selected viz A 13 and GR23 which were binucleate and did not anastomose with the selected virulent isolates, offered the maximum protection to the rice plants from sheath blight. The plants treated with GR23 showed immune reaction to challenge inoculation with virulent isolate, showing no symptom production on challenge inoculation with virulent isolate. The protective effect was found to be higher than that of chemical and biological control treatments. The phenol oxidase activity in the plants treated with the hypovirulent isolates was found to be significantly higher than that of the plants treated with virulent isolate while the peroxidase activity was higher in the plants treated with virulent isolate. Among the different carrier materials tested for hypovirulent Rrsolani rice bran was found to be good for long term storage and coirpith was found to be a cheap indigenous material for its mass multiplication.ThesisItem Open Access Comparative efficiency of lignocellulolytic fungi for bioconversion of coirpith(Department of Plant Pathology, College of Agriculture, Vellayani, 2002) Reeja, R S; KAU; Lulu DasNine lignocellulolytic fungi, of which SIX viz., Pleurotus eous, P. squarrosulus, two strains of Calocybe indica, Schizophyllum commune and Coprinus comatus collected from Thiruvananthapuram district as a part of the study entitled "Comparative efficiency of lignocellulolytic fungi for bioconversion of coirpith" and three from AfCRP Centre on Mushrooms, College of Agriculture, Vellayani were used to find out their ability to decompose coirpith. All these fungi preferred natural media such as Oatmeal Agar and Potato Dextrose Agar, a temperature range of 25 -. 35°C and neutral to acidic pH for their optimum growth. , ' I In vitro studies were conducted to find out the efficient strains. Pre and post composting physico-chemical analysis were carried out. Coirpith was found to be acidic in nature. EC of non retted coirpith was very high. Ability of these fungi in degrading organic carbon, cellulose and lignin thereby narrowing down the C : N ratio and increasing the nutrient status were found out. Field level trials using P. eous, P. squarrosulus, P. sajor-caju, P. florida, C. indica-Z and S. commune revealed that all these fungi could efficiently degrade coirpith, Better degradation of retted and non retted coirpith was observed when they were inoculated with lignocellulolytic fungi for 45 days. Maximum reduction in organic carbon and C : N ratio was brought about by P. eous and S. commune in non retted coirpith. Higher concentration of nitrogen was observed in retted coirpith inoculated with the same fungi. The phosphorus content was maximum m non retted coirpith inoculated with P. eous, C. indica-Z; S. commune and P. squarrosulus. Maximum potassium content was observed In non retted coirpith treated with P. eous and P. sajor-caju. P. eous and P. sajor-caju treated retted coirpith brought about maximum reduction in cellulose, while lignin degradation was maximum for P. sajor-caju and P. eous treated non retted coirpith. P. eous brought about the maximum reduction in weight of retted and non retted coirpith, while maximum volume reductioh was noticed in retted and non retted coirpith inoculated with P. eous and S. commune respectively. The final compost was dark brown in colour with low levels of organic carbon, cellulose, lignin, narrow C : N ratio and with increased nutrient status. The results of the experiment clearly showed that P. eous, P. sajor- caju and S. commune are efficient decomposers of coirpith.ThesisItem Open Access Evaluation of fluorescent pseudomonads for the management of sheath blight and bacterial blight of rice(Department of Plant Pathology, College of Agriculture, Vellayani, 2002) Heera, G; KAU; Kamala, NayarBiological control of major foliar diseases of rice in Kerala viz., sheath blight and bacterial blight using fluorescent pseudomonads was studied. Isolates obtained from the phylloplane were observed to be effective In inhibiting the growth of foliar pathogens. Isolate P 11 was most effective In inhibiting the growth of Rhizoctonia solani inciting sheath blight disease whereas growth of bacterial blight pathogen Xanthomonas oryzae pv oryzae . was suppressed by the isolate P33, under in vitro conditions. P 11 and P33 survived well in the inert material talc used as carrier material in the formulation developed, using these isolates. Seed treatment with talc based formulation of each isolate (P 11 and P33) increased the dry weight of root and shoot of rice seedlings of cultivar Jyothi and TN-l 14 days after sowing. The isolates produced almost equal and detectable amounts of IAA in culture supernatant. Greenhouse studies conducted at the College of Agriculture, Vellayani, indicated that a combination of seed treatment (10g kg" seed), seedling root dipping (1 per cent solution), and foliar spray (1 per cent) with the formulation of PI 1 and P33 effectively suppressed sheath blight and bacterial blight disease respectively and also appreciably increased the biomass yield of treated rice plants. Three foliar sprays starting two days prior to inoculation with the pathogen, during the tillering stage of the crop enhanced the efficacy of seedling root dipping with the biocontrol formulation. Isolates P 11 and P33 were tentatively identified as Pseudomonas aeruginosa and Pseudomonas fluorescens biovar 1 respectively.ThesisItem Open Access Integrated management of bacterial wilt of tomato caused by Ralstonia solanacearum (Smith) Yabuuchi et al.(Department of Plant Pathology, College of Horticulture, Vellanikkara, 2002) Akbar, K I; KAU; Sheela Paul, TBacterial wilt of tomato caused by Ralstonia solanacearum (Smith) Yabuuchi et al. has continued to be a perennial problem due to its complex interaction with soil. Hence a study has been taken up to isolate a potent biocontrol organism and to develop a strategy by integrating the selected control methods so as to have a sustainable eco-friendly tomato production. The pathogenic bacterium R. solanacearum was isolated from four different locations and the characterization studies revealed that the four isolates of the pathogen belong to R. solanacearum race 1 biovars3. The antagonistic bacterium isolated from the central zone was capable of producing abundant bluish green diffusible fluorescent pigment and a non diffusible non fluorescent brown pigment in King's B medium. Based on the physiological and biochemical studies, this bacterium was tentatively identified as Pseudomonas aeruginosa. Seed treatment - with _ antagonistic bacterium facilitates earliness ID germination and better plant VIgOur in both Pusa Ruby and Sakthi varieties compared to other treatments, Data on solarisation studies also showed that solarisation for 30 days has a weak effect in checking the R. solanacearum population. In bioassay studies garlic 10 per cent and the Copper fungicides, Bordeaux mixture 1 per cent and Copper hydroxide 0.15 per cent were sensitive to Risolanacearum but insensitive to P. aeruginosa. In pot culture studies, the seeds of the resistant variety Sakthi treated with beneficial agent, garlic drenching or Bordeaux mixture drenching were found to be superior to all other treatments in reducing the wilt incidence. In the main field, treatment combinations were tried based on the results of pot culture experiments. The rate of increase in wilt incidence was highest in the early stages and at flowering stage. The plants withstand bacterial infection upto flowering stage because of the resistant mechanism present in the variety Sakthi. The result of the study indicated that the bacterial disease of tomato could be effectively managed by integrating indigenous antagonistic activity of P. aeruginosa and selective bactericides like garlic extract or Copper hydroxide 0.15 per cent along with the host resistance of variety Sakthi.ThesisItem Open Access Biocontrol of anthracnose of black pepper (Piper nigrum L.) caused by Colletotrichum spp. using mycoparasites(Department of Plant Pathology, College of Agriculture, Vellayani, 2002) Anoop Sankar; KAU; Santhakumari, PAn investigation was done for exploiting potential biocontrol agents for the management of anthracnose of black pepper. Survey conducted on the incidence of anthracnose disease in eleven different locations of the state during February - July 2000 revealed that Colletotrichum gloeosporioides was the most common pathogen associated with this disease. Distinct variability in morphological characters and pathogenicity was exhibited by the di"fferent isolates of the pathogen. The most virulent isolate was isolate C6 from Perinthalmanna. The pathogen survived for three months on infected leaves in the soil and upto five months on infected leaves under laboratory conditions. A study was conducted to isolate potential mycoparasites of C. gloeosporioides from the rhizosphere and phyllosphere of both healthy and diseased black pepper plants from the various locations surveyed. Among the fungi isolated, two isolates of Trichoderma harzianum Rifai (T I and T 2) and two isolates of Aspergillus niger van Tieghem (A, and A2) were found to be most effective in' inhibiting C. gloeosporioides in vitro. After mass multiplication, the selected fungal antagonists were formulated in talc, which was found to be the best carrier material for maintaining the viability of the antagonists. The shelf life of the talc based formulations were 150 days and 180 days for the T. harzianum isolates and A. niger isolates respectively. The antagonistic fungi were tested separately under greenhouse conditions by a combination of two methods of application viz., soil application and foliar spray. Greenhouse studies indicated that all the four isolates were equally effective In suppressing the development of the disease in black pepper cuttings. Application of the talc based formulations of the four isolates in the soil @ 109 / kg soil followed by foliar spray with one per cent suspension of the talc based formulations twice at 15 days interval starting from 10 days after pathogen inoculation was very effective in controlling the disease under greenhouse conditions. In general, application of the fungal antagonists promoted the growth of black pepper cuttings. Isolate Al produced maximum shoot length, root length and fresh weight in the treated black pepper cuttings. The results of the study assigned dual roles as biocontrol agents and plant growth promoters for all the four fungal antagonists.ThesisItem Open Access Efficacy of selected biopesticides for the management of sheath blight of rice(Department of Plant Pathology, College of Horticulture, Vellanikkara, 2001) Saifunneesa, T K; KAU; Rehumath Niza, T JStudies on 'Efficacy of selected biopesticides for the management of sheath blight of rice' was conducted at the College of Horticulture, Kerala Agricultural University, Vellanikkara during 2000-2001. The major objective was to evolve a safer and eco-friendly management practice against sheath blight disease of rice. In vitro evaluation revealed Trichoderma viride and 2B as the best fungal and bacterial antagonists respectively. Fungi such as Aspergillus niger, A. terreus, Penicillium chermesinum, Cunninghamella bertholletiae and bacteria such as 1 B (Clostridium sp.), 4B, 7B (Bacillus sp.), lOB (Sporosarcina sp.), 19B (Bacillus sp.), 28B and Pseudomonas jluorescens showed significant inhibition of Rhizoctonia solani. Initial screening of the botanicals resulted in the selection of Chromolaena odorata, Leucaena leucocephala and Ocimum sanctum as the effective botanicals in the inhibition of R. solani. All these inhibited the formation of sclerotia even at five per cent concentration. Of the neem based formulations, Nimbecidine at 0.75 per cent concentration showed the maximum inhibition of 70.79 per cent and inhibited the sclerotial formation even at 0.5 per cent level. Comparative evaluation of microbial antagonists, botanicals and neem , based formulations were carried out in in vivo for the selection of potential ones to field experiment. In the present study T viride was selected as the best antagonist followed by 12B(Clostridium sp.), 28B, unidentified ascomycetes (20F), Acrophialophora sp., C. bertholletiae, Trichoderma sp. in that order. Among the botanicals C. odorata was the best as corroborated by the CODEX value of 3.56 and was followed by O. sanctum with a CODEX Value of five on 30th day of inoculation. Out of the two neem based formulations, Nimbecidine (azadirachtin 0.03%EC) showed the maximum control on the disease up to 30th day of inoculation (CODEX=1.17-2.29). The botanicals namely C. odorata, O. sanctum and neem based formulation Nimbecidine were found as effective as carbendazim 0.1 per cent. The effect of bioagent T. viride, neem based formulation Nimbccidine as well as botanicals C. odorata, O. sanctum and fungicide carbendazim were tested under natural field condition. To select the most effective schedule, the different combinations of biopesticides for seed, soil and foliar applications were tried. Among the different biopesticides T. viride applied on seed, soil and foliage (T3) showed maximum disease control and was equally effective as carbendazim O.lper cent. Seed treatment cum soil application of T viride (T2) came next in reducing sheath blight infection and has given the highest benefit: cost ratio. Treatment T3 was also economically viable as carbendazim 0.1 per cent. An increase in the activity of phenylalanine ammonia lyase (PAL) was noticed with the foliar spray of T viride, Nimbecidine, C. odorata, and carbendazim.
