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Open Access
Varietal screening of banana against anthracnose disease
(Department of Plant Pathology, College of Horticulture, Vellanikkara, 1984) Srinagesh, K L; KAU; Jose, P C
Laboratory and field studies of the varietal screening of banana against anthracnose disease were conducted at the college of Horticulture. Vellanikkara and at Banana Research Station, Kannara respectively during 1981-1983. In the field the infection started at the distal end of the banana fruit and in course of time the infected fruit became blackened, shriveled and mummified. After Harvest, the symptoms appeared as small brown spots which enlarged quickly and coalesced forming larger patches. The affected areas were covered with orange to salmon pink coloured conidial masses. The detailed morphological studies of the fungus proved that the anthraemose disease of banana is caused by colletrichum cloeosporioides cooko and massee, the imperfect stage of glomerella cinoulata spauld and shrenk. Twenty five varieties of banana fruit were screened in vitro at different stages of development against anthracnose disease. The varieties showed different degrees of susceptibility at various developmental stages of the fruit. The pooled analysis of the data showed that the variety nendra padaththi followed by palayankodan, jurmani kunthali, boodida bontha bathes, peyan, kanchikela, pisang mas and kapok were found to be highly resistant. The varieties Zanzibar, adakka kunnan, klue teparod, chinia, nendran, venneettu mannan, koduppilla kunnan, hybrid sawai, poocha kunnan, red banana and boodles altafort were found to be resistant to the disease. The variety robusta was found to be susceptible. The varieties njalipoovan, pisang lilin, dwarf Cavendish, matti and gros Michel were found to be highly susceptible. The major chemical constituents of banana fruit viz. reducing sugars, total sugars starch, crude fibre, crude protein and tannin at different developmental stages of twenty five varieties were analysed. The reducing sugars and total sugar were found to increase steadily from immediately after female phase to ripened stage in all the varieties. The starch and crude fibre contents, though increased steadily upto full maturity. Declined sharply at the ripening stage. The crude protein and tannin contents were maximum at immediately after female phase but steadily decreased and were minimum at ripening phase. There was a significant positive correlation between reducing sugars, total sugars and per cent disease intensity at three fourth maturity. High sugars were responsible for susceptibility to the disease. A significant negative correlation was obtained between crude protein and per cent disease intensity at half maturity. A significant negative correlation was also obtained between tannin and per cent disease intensity at one fourth and half maturity stages. High crude protein and high tannin contents were responsible for resistance to the disease.
Open Access
Ochratoxicosis in the goat
(Department of Pathology, College of Veterinary and Animal Sciences, Mannuthy, 1983) Maryamma, K I; KAU; Krishnan Nair, M
An 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.
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 R
1. 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.
Open Access
Studies on the phyllosticta leaf spot of ginger
(Department of Plant Pathology, College of Horticulture, Vellanikkara, 1981) Premanathan, T; KAU; Peethambaran, C K
Laboratory 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.
Open Access
Studies on the control of soft rot of ginger
(Department of Plant Pathology, College of Horticulture, Vellanikkara, 1980) Kurucheve, V; KAU; Peethambaran, E K
The present investigation ‘Studies on the control of soft rot of ginger’ was conducted at the Instructional Farm, attached to College of Horticulture, Vellanikkara, Trichur during the year 1978-79. Two varieties of ginger viz. ‘Rio-de-janeiro’ and ‘Maran’ were used for the investigations. The objectives of the investigations were 1) to find out the causal organism of soft rot of ginger in the acid lateritic soils of Vellanikkara 2) to find out suitable control measures against the disease 3) to know whether the fungus could develop resistance against continuous application of fungicides and 4) to find out any adverse effect on the development of ginger rhizomes when the fungicides were applied for controlling the disease. The pathogen responsible for the disease was found to be Pythium aphanidermatum (Edson) Fitzpatrick. More than 90 per cent inhibition of the fungus was observed by agallol, thiride and difolatan at 500 ppm concentration in vitro. Hundred per cent inhibition of the fungus was possible only with 2000 ppm of Cheshunt compound or thiride and with 500 ppm of agallol in vitro. Among the different combinations of Cheshunt compound, agallol and thiride, 100 ppm of agallol plus 100 ppm of thiride was the most effective combination in inhibiting the mycelial growth of the fungus. Seed treatment with 0.25 per cent agallol solution alone was not effective in reducing the disease incidence in the field. The fungicides which were proved very effective in in vitro studies, were again tested under field conditions. They were Cheshunt compound, agallol and thiride. Soil drenching before planting with the above mentioned fungicides reduced the pre emergence rotting considerably. Single application of fungicides either in one, three or four months after planting was not adequate in controlling the disease. A minimum of two post emergence applications i.e. One month and three months after planting either with cheshunt compound or agallol, in addition to pre planting soil drenching were necessary for controlling the disease as well as for getting good yield. P. aphanidermatum did not develop any resistance against the fungicides when they were applied continuously in the field. Adverse effect on the development of ginger rhizomes was not noticed when the fungicides were applied for controlling the soft rot of ginger. The present investigation showed that extent of control varied with the sequence and number of fungicidal applications. Treatments agallol – cheshunt compound, cheshunt compound – cheshunt compound and cheshunt compound – agallol in two times application; cheshunt compound – cheshunt compound – cheshunt compound ; cheshunt compound – agallol – thiride and cheshunt compound – thiride – agallol in three times application and cheshunt compound – cheshunt compound – cheshunt compound – cheshunt compound; agallol – agallol – agallol – agallol and cheshunt compound – thiride – agallol – cheshunt compound in four times application showed a better disease reduction compared to other treatments. The post emergence rotting started appearing from July and peak infection was noticed during August. The variety ‘Maran’ was more resistant to the disease. There was a direct correlation between the disease incidence and continuous rainfall.
Open Access
Studies on the microflora of stored pepper
(Department of Plant Pathology, College of Horticulture, Vellanikkara, 1982) Estelitta, S; KAU; Abi Cheeran
With 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.
Open Access
Studies on the leaf blight disease of clove caused by Cylindrocladium sp.
(Department of Plant Pathology, College of Agriculture, Vellayani, 1980) Sulochana, K K; KAU; Chandrasekharan Nair, N
Leaf blight disease of clove caused by Cylindrocladium cuinqueseptatum Boedijn et Roitsma was investigated. The fungus infected clove leaves at all stages of maturity, but the seedlings were found to be more susceptible to the disease than mature plants. Injury of the host tissue was found to be a pre-requisite for successful infection by the fungus. The organism infected a wide variety of plants including some of the weed plants on artificial inoculation. Good growth and sporulation of the fungus was obtained on potato dextrose agar followed by Coon’s agar and Czapek’s agar. In liquid media, maximum dry weight of the mycelium was obtained on potato media, maximum dry weight of the mycelium was obtained on potato dextrose broth, followed by Czapeks’ broth. Maximum growth of the fungus was obtained on medium amended with gingelly oil followed by coconut and clove oils. In liquid media, maximum dry weight of the mycelium was obtained in the medium amended with gingelly oil followed by coconut clove oils. Optimum pH range for the growth of the fungus was found to be 7 to 9. Richards’ broth was found to be the best medium for the production of toxin followed by Czapek’s and Fries’ media. Exotoxin production was found to be more than endotoxin. The toxic metabolite is found to be thermostable. Diluting the culture filtrate to 4 times its volume showed a reduction in the toxic effect. However, the treatments did not completely eliminated the toxic effect of the preparation. The toxic effect of the culture filtrate translocated by defoliation on the cut twigs of plants. Culture filtrate of the fungus inhibited the spore germination of Colletotrichum glocosporioides and Curvularia sp. The culture filtrate as well as the mycelial extract produced lesions on clove leaves of different maturity, with pronounced effect on tender leaves. Spore germination of the fungus could be completely inhibited with all the eight fungicides in all concentrations on the first day of observation. Daconil-2767, Dithane M-45, Fytolan and Thride were able to cause 94,97,94 and 95 per cent inhibition of spore germination respectively upto 12th day at maxium concentration tested ( 3000 ppm). Growth of the fungus was completely inhibited with Bavistin 250, 500 and 1000 ppm, Dithane M-45 1000, 2000 and 3000 ppm; Mildothane 500, 1000 and 2000 ppm and thride 1000, 2000 and 3000 ppm; when tested in czapeks’ agar medium. In czapeks’ solution Bavistin, Difolatan, Dithane M-45 and Mildothane at all concentrations tested, there was complete inhibition of growth of the fungus. Bavistin at 250 ppm and Thiride at 1000 ppm were able to inhibit the growth of the fungus by 15 minutes immersion, when the culture dises were tested for the viability of the fungus, Mildothene and Dithane M-45 inhibited the growth of the fungus at 1000 and 2000 ppm respectively, When the culture discs were tested for the viability of the fungus after immersion for one hour in fungicidal solution. Fytolan and Difolaton were able to inhibit the growth of the fungus at the maximum concentration (both at 3000 ppm), only after 24 hours immersion in the fungicidal solution.
Open Access
Seed mycoflora of some vegetables in Kerala
(Department of Plant Pathology, College of Agriculture, Vellayani, 1981) Naseema, A; KAU; Balakrishnan, S
The 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.
Open Access
Etiology and control of bacterial leaf blight of rice caused by Xanthomonas oryzae (Uyeda and Ishiyama) Dowson
(Department of Plant Pathology, College of Agriculture, Vellayani, 1980) Mary, C A; KAU; James Mathew
The bacterial leaf blight of rice, incited by Xanthomonas oryzae (Syeda and Ishiyama) Dowson is one of the most serious disease of economic importance in India and several other rice growing countries of the world. This disease was first reported in India by Sreenivasan et. al. (1959) from Maharashtra and a serious epiphytetic was reported by Srivastava and Rao (1963) from Bihar. In Kerala , eventhough severe epiphytotics of this disease have not been reported so far, the disease is endemic in the major rice growing areas of Kuttanad and Palghat. The pathogen was identified as Xanthomonas oryzae (Uyeda and Ishiyama) Dowson based on its morphological , cultural , physiological and biochemical characters together with its pathogenicity. For laboratory studies and mass culturing of the organism, Glucose Yeast extract Agar and Glucose Agar were found to be the best solid media and Glucose Yeast extract chalk broth and potato Sucrose Peptone broth were the best liquid media. The pathogen was found to survive in infected seeds for a period of 90 days , in infected debris in soil for a period of 28 days and in infected soil for less than a week indicating that the infected seeds and infected plant debris in soil play an important role in the epidemiology of the disease.

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