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ThesisItem Open Access Ochratoxicosis in the goat(Department of Pathology, College of Veterinary and Animal Sciences, Mannuthy, 1983) Maryamma, K I; KAU; Krishnan Nair, MAn experimental study was carried out to delineate the pathological effects of ochratoxin in goats. A comparative assessment of ochratoxin production by A. ochraceus and A. sulphureus on what and rice under static and shake cultures was also made. A. ochraceus was found to be a better toxin producing strain in both substrates under static and shake cultures systems and wheat was a better substrate than rice. Toxicity studies were conducted in Sannen – Malabari cross-bred goats of 1 to 3 months age. Purified ochratoxin produced in the laboratory was administered by oral, intra-peritoneal and intravenous routes. The different dose levels adopted were 2.5 mg/kg body weight, 1 mg/kg body weight and 0.5 mg/kg body weight. The synergistic effect of ochratoxin and aflatoxin in goats was studied by adminstering the crystalline toxins simultaneously (Makor Chemicals, Israel) by itraperitoneal route. The parameters of study were: clinical signs, haematological and biochemical alterations, pathological changes in urine, and macroscopic, microscopic and ultra-structural alterations in organs. Varying degree of clinocopathological changes were noticed in the test animals. The animals became weak and listless and in general there was reduction of total erythrocyte count, PCV, haemoglobin and lymphocyte count. Serum protein level was lowered while BUN and creatinine and blood coagulation time were high. There was rise in ALP, SGOT and SGPT in some of the test animals. The changes and degree of variation depended on the dose, total quantity and rate of administration of the toxin and duration of the experiment. More severe alterations were noticed when ochratoxin and aflatoxin were administered simultaneously. Important changes in the urine were lowering of pH, albuminurea and presence of epithelial cells and casts. Pathological changes varied in severity in different organs and were observed in the following descending order: kidney, liver, intestines, stomach, lymph nodes, spleen, thymus, genital organs, endocrines. In the kidneys, the order of intensity of pathological alterations was: proximal convoluted tubules, Henle’s loop, distal convoluted tubule, glomeruli, collecting tubules. Retrogressive changes of different degree and necrosis of the lining epithelial cells of tubules and endothelium and epithelium of glomeruli were the important lesions. Changes in glomeruli and Bowman’s capsule noticed in the higher dose group included shrinkage of glomeruli and presence of proteinaceous material in the capsular space. Eosinophilic granular casts and PAS positive bodies were present in the lumen of tubules. The necrobiotic renal changes were more intense when orchatoxin and aflatoxin were administered simultaneously. Hepatic lesions were mainly fatty infiltration, necrosis of hepatocytes and haemorrhage. The changes were most severe in combined toxicity. Mallory bodies and mild biliary hyperplasia were noticed in a few sections. Necrosis and subsequent depletion of lymphocytes wee the lesions in lymph nodes, spleen and thymus in some test animals. Degenerative changes were also noticed in testis, ovary, pituitary, adrenals and pancreas in experimental groups. In the combined toxicity group the pathological effect was more intense. At the ultra-structural level, the hepatcytes as well as the epithelial cells in the kidney showed severe changes. The cell organelles were either completely damaged or showed partial configurational alterations. Mitochondria showed changed in the density of matrix as well as disorientation and destruction of the limiting membranes and cristae. Cytolysosomes incorporating damaged cell organelles were abundant. Disaggregation of ribosomes and fragmentation of ER were noticed. In the glomerulus, there was destruction of the basement membrane and disruption of the regular arrangement of the foot processes of podocytes. In the cytoplasm of hepatocytes, Mallory bodies and lipid droplets were present. Varying degree of nuclear changes like clumping, condensation and disappearance of chromatin and fragmentation of nucleolus and nuclear membrane were observed. Changes occurred in the tight junctions of epithelial cells of bile ducts. Pathological alterations were more pronounced when ochratoxin was administered by the pwerenteral route. Oral administration of toxin also effected structural alterations which indicated that some fraction of ochratoxin escaped degradation in the rumen. From this study it became evident that aflatoxin potentiated the effect of ochratoxin. The structural damage to the cells might be due to the inhibition of oxidative enzymes which is reflected by the extensive ultra- structural alteration observed in the mitochondria and RER. Biochemical changes like high BUN and creatinine were evidently due to necrobiotic changes in the kidney. Interference in the synthesis of proteins due to damage of hepatic cells and escape of protein molecules due to alteration in the podocyte foot processes and basement membranes may account for the reduced serum protein levels. The nature of organellar destruction and configurational changes in the cells indicate the toxic potency of the mycotoxin on the biological system.ThesisItem Open Access Studies on purple top roll (PTR) of potato in Karnataka(Department of Plant Pathology, University of Agricultural Sciences, Bangalore, 1983) Sreedharan, A; KAU; Reddy, H R1. Survey for the incidence of potato purple top roll revealed that the disease was present in Bangalore, Belgaum, Dharwad, Hassan and Kolar districts of Karnataka. The average percentage of incidence varied from 8.94 to 50.07. The survey also indicated that there was low incidence of the disease in summer and high incidence in kharif and rabi. 2. The pathogen was transmissible by wedge, side and core grafting. 3. The disease was transmitted through dodder, Cuscuta chinensis Lam. 4. The disease was not transmissible through sap and aphids Myzus persicae Sulz. And Aphis gossypil Glov. 5. The etiological agent was transmitted by the leafhopper, Orosius albicinctus Distant and not by Hishimonus phycitis Distant. 6. The vector, O. albicinctus could acquire the pathogen in two hr and inoculate to healthy plants in 30 min. The percentage of active transmission was 35 – 40 and the minimum incubation period in the plant was between 20 and 25 days. Maximum percentage of transmission was obtained on 40th day after inoculation. 7. Characteristic symptoms of the disease was inward rolling of basal parts of top leaflets, purple/pink pigmentation, smalling of leaves, excessive proliferation of axillary buds, erect appearance, production of purple coloured, aerial tubers and stunting and dwarfing of plants. 8. The etiological agent infected tomato, tree tomato, Datura stramonium and D. metel by grafting. 9. The pattern of spread of the disease in the field was from external source in the beginning and later the spread was within. 10. The vector population was correlated with the disease incidence in the field. The increase in the incidence of the disease followed the increase in the vector population. 11. The leafhopper vector, O. albicinctus Distant was high in the months from late June to December and low from January to early June. 12. The high population of leafhoppers was correlated with low temperature and high humidity and low population was correlated with high temperature and low humidity. 13. The disease appeared 40 days after planting in the field and then it gradually increased reaching the peak by 90th day. 14. The pathogen was transmitted through tubers for two successive generations but to a lower percentage in the second generation. 15. Of the 36 cultivars/varieties of potato tested under field conditions, none were found to be resistant, However, the vars. JF 542, JF 4612, JG 676, JG 900, JC 750 and JE 812 had less than five per cent infection. Kufri Chandramukhi and Kufri Jyoti were highly susceptible having 48.3 and 47.6 per cent incidence, respectively. The highest average incidence of PTR in these cultivars in farmer’s fields was 35.85 and 26.03 per cent, respectively. 16. There was considerable loss in yield in many cvs. Viz., JC 750, BS/F 100, JC 182 and EM/F 2120. 17. The weight of tubers produced by the infected plants was always less than the tubers obtained from the adjacent healthy plants. The infected plants produced more number of smaller tubers which aggregated close to the main stem attached on short stolons. 18. Complete remission was obtained at 500, 1000 and 2000 ppm, incomplete remission at 100 and 250 ppm and no remission at 50 ppm of tetracycline given alternatively for 20 days.ThesisItem Open Access Studies on the phyllosticta leaf spot of ginger(Department of Plant Pathology, College of Horticulture, Vellanikkara, 1981) Premanathan, T; KAU; Peethambaran, C KLaboratory and field experiments of “The studies on the Phyllosticta leaf spot of ginger” were conducted at the College of Horticulture Campus, Vellanikkara during 1979-1981. The first visible symptom of the disease was observed as chlorotic specks. Fructification was more during the later stages of crop growth. The detailed study on the plant and environmental factors influencing the disease development in the field revealed that the average number of leaves per plant has a significant positive correlation with the disease intensity. Koch’s postulate and morphological studies proved that the pathogen causing the disease is Phyllosticta zingiberi Ramakr. Uninjured leaves and first three leaves, even after injury, failed to exhibit the symptoms on inoculation. Conidia germinated by putting forth single or double germtubes. Sucrose solution (1,000 ppm) supported faster and maximum spore germination and the bipolar germination noted was maximum in this solution. The fungus entered the leaf by direct penetration of epidermal cells without appressoria formation. The pycnidiospores and mycelia of the pathogen were found to survive even after seven months in soil under different depths and moisture conditions. The type Maran was found to be the least susceptible followed by Karakkal and Bajpai, whereas type Vengara was the most susceptible one. Out of the 12 fungicides tried, one per cent Bordeaux mixture and 2,000 ppm Bayer 5072 gave cent per cent inhibition of the fungal growth in both solid and liquid media. Antracol 2,000 ppm and panolil above 500 ppm in solid medium; bavistin 2,000 ppm and cuman above 500 ppm in liquid medium gave cent per cent inhibition of fungal growth. In the field trial cuman, was found to be the most effective fungicide in controlling the disease, followed by Bordeaux mixture and panolil. Maximum rhizome yield was noticed in cuman treated plots followed by Bordeaux mixture.ThesisItem Open Access Studies on the microflora of stored pepper(Department of Plant Pathology, College of Horticulture, Vellanikkara, 1982) Estelitta, S; KAU; Abi CheeranWith a view to study the microflora in stored black pepper, a research project was carried out at the College of Horticulture, Vellanikkara. It was also aimed at estimating the deterioration of the quality of stored black pepper in terms of its oleoresin, piperine and starch contents due to microbial infection and assessing the role of each micro-organisms in changing the quality of the product. The study revealed that the major chemical constituents of stored black pepper, namely, oleoresin, piperine and starch varied in different grades of black pepper. Slight variations in these quality constituents were observed according to the seasons of storage also. In all the seasons, association of microflora with all grades of black pepper was observed. The species of micro-organisms were not changed during seasons, but the population varied according to grade of black pepper and season of storage. The micro-organisms found were Aspergillus niger, A. candidus, A. nidulans, A. versicolor, curvularia lumata, penicillium citrinum, Fusarium moniliforme, Rhizopus nigricans and Bacterium (gram –ve). There was no growth of microflora in stored black pepper upto 66.8 per cent relative humidity, whereas profused growth was observed at saturation levels of humidity. Only Aspergillus spp. And penicillium citrinum could come up at a lower HUMIDITY LEVEL (75.6 per cent). In three quality constituents of black pepper viz., oleoresin, piperine and starch reduced considerably when the samples were inoculated with different micro-organisms at different levels of humidity. Reduction in the quality constituents was found corresponding to the increase in level of humidity as well as length of incubation period.ThesisItem Open Access Seed mycoflora of some vegetables in Kerala(Department of Plant Pathology, College of Agriculture, Vellayani, 1981) Naseema, A; KAU; Balakrishnan, SThe survey of the seed mycoflora of vegetable seeds revealed the presence of a number of seed-borne fungi. Storage fungi like Aspergillus flavus, Aspergillus niger Penicillium sp. and Rhizopus stolonifer were found to be externally as well as internally seed-borne , in almost all the vegetable seeds taken for the study. A part from these , other fungi like Curvularia lunsta. Fusarium equlecti and Myrothecium roridum from amaranthus , Botryodiplodia theobrease from bhindi, bitter gourd and cowpea, Fusarium oxysporum and Eectria haemtococca from bhindi, Achaetonium macrosporum and Collstrotrichum lagenarium from bitter gourd, Drechalera rostrata from cowpea, Cephaliophora irregularis and Fusarium solani from pumkin were obtained. The seed-borne fungi were found to cause inhibitory effect on the germination of the seeds , from which they were isolated , Maximum inhibition in the germination was found to be caused by storage fungi like Aspergillus flavus, Aspergillus niger. Penicillium sp. and Rhizopus stolonifer . Rotting of the seedlings was caused by Fusarium equiseti on amaranthus, Prechslera rostrata on cowpea . Aspergillus niger and Rhizopus stolonifer on tomato.ThesisItem Open Access Role of weeds in the perpetuation of virus diseases of vegetables and ornamental plants(Department of Plant Pathology, College of Agriculture, Vellayani, 1981) Mathew, A V; KAU; Balakrishnan, SVirus diseases affecting ten different weed plants and their possible role in the perpetuation of virus diseases of certain cultivated plants were investigated. These ten weeds were affected by 13 virus diseases. All the 13 viruses were transmitted by wedge grafting. Among the 13 viruses studied, 3 viruses, viz., mosaic of Amaranthus viridis yellow mosaic of Micrococca mercurialis and mosaic Stachytarpheta indica were transmitted by sap inoculation and by insect vectors. Eight viruses, viz., yellow vein mosaic of Ageratumconizoides, leaf curl of A. conizoides, yellow vein mosaic of Croton sparsiflorus and Sida cordifolia, yellow mosaic of Micrococca mercurialis, leaf curl of Stachytarpheta indica and Synedrella nodiflora and yellow mosaic mottle of Stachytarpheta indica var. jamaicensis were transmitted by the whitefly, Bemisia tabaci Genn.ThesisItem Open Access Studies on host-varietal specificity for Rhizobium for nodulation in groundnut(Department of Plant Pathology, College of Agriculture, Vellayani, 1982) Girija, V K; KAU; Sasi Kumar, NairAn investigation was carried out at the College of Agriculture, Vellayani, Kerala to study the host-varietal specificity, if any, for Rhizobium for nodulation in groundnut. A total of fifteen groundnut varieties were subjected to a preliminary screening on the basis of the number of nodules formed and arranged into five distinct nodulation groups. Seven varieties of groundnut TMV-12, USA-123 Exotic-6, Spanish Peanut, TMV -11, Ak12-24 and Ah-32 were selected from among these groups for use in further studies.ThesisItem Open Access 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; KAU; Chandrasekharan Nair, MRhizoctonia 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.ThesisItem Open Access Symptomatology etiology and control of sheath rot disease of rice caused by Acrocylindrium oryzae(Department of Plant Pathology, College of Agriculture, Vellayani, 1981) Balakrishnan, B; KAU; Chandrasekharan Nair, MSheath rot disease of rice caused by Acrocylindrium oryzae was investigated. The fungus was found to infect rice plants at boot leaf stage. The leaf sheath covering the panicle was found to be comparatively more susceptible to the fungus than the sheath of other leaves. Severe infection caused choising of the whole penicle insids the sheath itself before emergence. The pathogen was isolated from infected tissues of host plants and brought into pure culture. Comparative studies of air isolates of Acrocylindrium oryzae from four rice varieties and two weed hosts did not show much appreciable difference in their morphological characters except light variations in the hyphal thickness and smaller conidial size from those on weed hosts.