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Open Access
Associative effect of azospirillum and bradyrhizobium on nodulation and growth of cowpea (viqna unquiculata (l.) walp,
(Department of Plant Pathology College of Horticulture Vellanikkara, 1992) Sunitha, Menon S.; KAU; Rajendran, Pillai M .V
Open Access
Fungal diseases of selected medicinal plants of Kerala
(Department of Plant Pathology, College of Horticulture, Vellanikkara, 1991) Sukumara, Varma A; KAU; ; Abi, Cheeran
Open Access
Leaf blight of banana and its control
(Department of Plant Pathology, College of Agriculture, Vellayani, 1993) Saj, KV; KAU; Sulochana, K K
Survey conducted to study the fungal pathogens causing leaf blight disease in banana in the three agricultural subdivisions of Thiruvananthapuram district, yielded seven fungal pathogens viz., colletotrichum musae, Curvularia sp, Guignardia musae, khuskia oryzae, Nodulisporium gregarium, Pestalotiopsis versicolor and Phaeoseptoria sp. Among these, Curvularia sp, Khuskia oryzae and Nodulisporium gregarium are new reports. Morphological characters and pathogenicity tests of all the seven isolated cultures were studied and described. Detailed studies were conducted on five fungal pathogens viz., C. musae, G. musae, K. oryzae, N. gregarium and Phaeoseptoria sp., since severe infections could be noticed by these fungi. Studies conducted on the growth and sporulation of pathogens on different, media indicated that Richard’s medium was the best for C. musae and G. musae, potato dextrose medium for K. oryzae and Phaeoseptoria sp. In the case of N. gregarium, potato dextrose agar and Czapek (Dox) broth were found to be the best solid and liquid media respectively for its growth. Best growth of C. musae, N. gregarium and Phaeoseptoria sp was obtained with maltose as the carbon source, whereas G. musae and K. oryzae utilized maximum starch and sucrose for their growth. Maximum mycelial weight of C. musae was obtained with sodium nitrate as nitrogen source, G. musae and K. oryzae with potassium nitrate, N. gregarium with glutamine and Phaeoseptoria sp. with asparagine. Potato dextrose broth and Richard’s solution were found to be best media for the toxin production by C. musae K. oryzae , G. musae and Phaeoseptoria sp. produced maximum toxin in Richard’s solution and N. gregarium in potato dextrose broth. Host range studies of the pathogen (s) conducted indicated that they can infect a number of economically important plants like, clove, cocoa, colocasia, nutmeg and tapioca, but none of the pathogens could infect clerodendron. Dithane M-45, calixin and Bavistin were able to inhibit the growth of the leaf blighting pathogens under laboratory conditions and under field conditions Dithane M-45 (0.2%) was found to be the best. Varietal screening trials showed that variety Rasakadali was moderately resistant/tolerant among the four popular varieties screened, whereas Nendran was the most susceptible variety.
Open Access
Combatibility of certain fungicides and insecticides used for the control of major diseases and insect pests infesting the rice crop
(Department of Plant Pathology, College of Horticulture, Vellanikkara, 1992) Kalpana, T A; KAU; Sally Mathew, K
The efficacy of four fungicides and four insecticides alone and in combination was studied at different concentrations recommended, three-fourth and half the recommended concentrations against two major diseases of rice namely, rice blast caused by Pyricularia oryzae Cavara and sheth blight caused by Rhizoctonia solani kahn. And two major insect-pests namely, leaffoldar Cnaphalocrocis medinalis medinalis Guen. And brown planthopper Nilaparvatha lugens stal. At tillering, panicle initiation and flowering stage of the crop. The experiment was conducted in vivo and in vitro conditions during 1989-91, at the college of Horticulture, Vellanikkara, Thrissur. In general combind application of fungicides and insecticides controlled the diseases and insect-pests more effectively than the treatments given separately. At tillering stage, a synergistic effect of fungicide was observed, when it was sprayed along with insecticides. Among different combinations tried, tridemorph (o.1 per cent) + monocrotophos (0.0375%) and carbendazim (0.075 ) + guinalphos (0.025 per cent) were the best combinations against blast and sheath blight respectively. In the case of leaffolder and brown planthopper, quinalphos was found to be the best insecticide, when used alone and also in combination with fungicides. At panicle initiation stage, combined sprays of higher concentrations of carbendazim and monocrotophos was the best combination in controlling both R. solani and N. lugeas. But ediphenphos-phosphamidon combination was found to be the superior against N. lugens. When combind spraying was given at flowering stage, captafol (0.225 per cent) + quinalphos (0.0375 per cent, and carbendazim (0.075 per cent) + monocrotophos (0.0375 per cent) were found to be the best combinations against P. oryzae and R. solani respectively. But, combination of recommended doses of quinalphos with tridemorph and ediphenphos and, phosalone with ediphenphos were the effective treatments in controlling C. medinalis and N. lugens respectively. In in vitro studies, a total inhibition of the test organisms, viz.P. oryzae and R. solani were observed in all the treatments. Whereas, in the case of C. medinalis recommended doses of quinalphos in combination with ediphenphos and carbendazim and phosalone with tridemorph recorded highest mortality; while, highest dose of quinalphos with captafol and phosalone with ediphenphos were the superior combinations against N. lugens. From the above findings it could be concluded that, the fungicides viz. ediphenphos, carbendazim, captafol and tridemorph are compatible with all the four insecticides tried viz. Phosphamidon, quinalphos, phosalone and monocrotophos in controlling the diseases, blast and sheath blight and insect pests leaffolder and brown planthopper.
Open Access
Improvement on the techniques for the cultivation and preservation of tropical species of mushrooms
(Department of Plant Pathology, College of Agriculture, Vellayani, 1994) Balakrishnan, B; KAU; Chandrasekharan Nair, M
Intensive collections made from certain selected areas of Kerala yielded a total of eight species of Pleurotus, one species each of Volvariella and Tricholoma, namely V. esculenta and T. lobayense respectively from the native flora. Various species collected were identified and based on the preliminary observations made on their adaptability for large scale cultivation, among the Pleurotus two species have been selected for detailed study along with the other standard cultures procured from various mushroom research centres of the country. The native isolate of T. lobayense in the present study is the first record of the species from Kerala. Detailed studies have been done on various aspects of cultivation of pleurotus spp. With a view to improve the already known technologies so as to suit the conditions of Kerala. The two native species of pleurotus selected have been domesticated and compared with other standard cultures on their performance. Based on the observations made in the seasonal influence, yield and market qualities the species most suited for large scale cultivation in Kerala have been identified. Alternative local substrates for cultivation of oyster mushrooms have been identified and their processing technology standardized. Effective nutritional supplements for increased yield, method for speedy induction of sporocarp, after care method for the once harvested beds for further flushes, effective method for cultivation etc. have been worked out for large scale cultivation of Pleurotus spp. In Kerala. Commonly available low cost substrates in spawn production have been identified and their technologies standardized. Influence of light on spawn growth, influence of storing environment on growth and shelf life of spawn etc. have been studied. Technology for preparation of an instant liquid spawn developed and also a modified method for speedy and low cost production of spawn using polypropylene cover as the container has been standardized. The effect of coconut milk in blending culture media for enhanced growth of various Pleurotus spp. and the effect of coconut milk in their biomass production have been proved. In the strain improvement programme, a substrate influenced mutant of Pleurotus sajor-caju for better yield, a resistant/tolerant strain against the most destructive weed mould Trichoderma viride and an interstock hybrid with desirable traits have been developed. Type of pests and their control etc. have been worked out. The effect of chemical pasteurization of the substrates on checking the weed mould infestation during spawn run and the use of lime powder for spot treatment of beds in the management of T. viride have been proved. Post harvest technology for preservation of both raw and dehydrated forms of mushrooms has been standardized. The native strains of other tropical mushrooms locally collected namely V. esculenta and T. lobayense have been identified based on the detailed description of the same. The performance of the native strain, V. esculenta under cultivation has been compared with that of the standard species, V. volvacea and a technique for cultivation of T. lobayense has been standardized for first time in this part of the country.
Open Access
Bio-deterioration of important cucurbitaceous seeds due to mycoflora
(Department of Plant Pathology, College of Horticulture, Vellanikkara, 1990) Saleena George; KAU; Cheeran, A B I
The study "Bio-deterioration of important cucurbitaceous seeds due to mycoflora" was conducted at College of Horticulture, Vellanikkara. The objectives of this study were to find out the role of seed borne mycoflora on the bio-deterioration of important cucurbitaceous seeds, the variation in the seed mycoflora in different periods of the year, to assess the role of different humidity levels on the viability of seeds and to evolve a suitable management practice to prevent the bio-deterioration of seeds. The study revealed that the unsterilised seeds were found associated with mycoflora throughout the period of investigation . Mycoflora associated with surface sterilised seeds was less than that of unsterilised seeds. The maximum fungal association was found on the seed coat, then in the endosperm and least in the embryo in all the three vegetable seeds. Twentyseven species of fungi were found associated with bitter gourd seeds . Ten of them were external contaminants. Twentyfive species of fungi were obtained from the cucumber seed of which 11 species were found to be externally seed borne fungi were Aspergillus sp., Pencillium sp. and Rhizopus sp. while among the internally seed borne fungi the predominant ones were Fusarium solani, Aspergillus flavus and Rhizopus stolonifer.
Open Access
Characterization and management of bacterial wilt of chillies caused by Pseudomonas solanaceasum E F Smith
(Department of Plant Pathology, College of Horticulture, Vellanikkara, 1992) Jyothi, A R; KAU; Koshy Abraham
Bacterial wilt is one of the most serious disease of chillies in Kerala. The pathogen was isolated from infected chilli plants and its pathogenicity established. Ten isolates of the pathogen viz., five from chillies , two each from tomato and brinjal and one from ginger were used in the study and they werre characterized and identified as blovar III of Pseudomonas solanacearum (Smith) Smith based on the morphological, cultural, biochemical and physiological characters, coupled with its pathogenicity. Twentynine accessions/varieties of chillies were screened for host resistance against bacterial wilt and the study revealed that the variety 'Manjari' (KAU Cluster/CA 33) was resistant to the disease. The accessions CA 205 and CA 207 exhibited moderately resistant reaction. There was no significant correlation between environmental factors and wilt incidence of all the accessions/varieties except CA 408, for which a positive correlation was noticed between soil moisture and wilt incidence.
Open Access
Compatibility of certain fungicides and insecticides used for the control of major diseases and insect pests infesting the rice crop
(Department of Plant Pathology, College of Horticulture, Vellanikkara, 1992) Kalpana, T A; KAU; Sally, K Mathew
The efficacy of four fungicides and four insecticides alone and in combination were studied at different concentrations (Recommended, three-fourth and half the recommended concentrations) against two major diseases of rice namely, rice blast caused by Pyricularia oryzae Cavarn and sheath blight caused by R hizoctonia solani Kuhn, and two major insect-pests namely, leaffolder Cnaphalocrocis medinalis Guen. and brown planthopper Nilaparvatha lugens Stal. at tillering, panicle initiation and flowering stages of the crop. The experiment was conducted in vivo and in vitro conditions during 1989-'91, at the College of Horticulture, Vellanikkara, Thrissur. In general, combined application of fungicides and insecticides controlled the diseases and insect-pests more effectively than the treatments given separately. At tillering stage, a synergistic effect of fungicide was observed, when it was sprayed along with insecticides. Among different combinations tried, triaemorpV. (0.1 per cent) + monocrotophos (0.0375%) and Carbendazim TO. 07‘5 % ) -:- quinalphos (0.025 per cent) were the best combinations against blast and sheath blight respectively. In the case of leaffolder and brown planthopper, quinalphos was found to be the best insecticide, when used alone and also in combination with fungicides. At panicle initiation stage, combined sprays of higher concentrations of carbendazim and monocrotophos was the best combination in controlling both R. solani and N. lugens. But ediphenphos-phosphamidon combination was, found to be the superior against N. lugens. When combined spraying was given at flowering stage, captafol (0.225 per cent) + quinalphos (0.0375 per cent) and carbendazim (0.075 per cent) + monocrotophos (0.0375 per cent) were found to be the best combinations against P. oryzae and R. solani respectively. But, combination of recommended doses of quinalphos with tridemorph and ediphenphos and, phosalone with ediphenphos were the effective treatments in controlling C. medinalis and N. lugens respectively. In in vitro studies, a total inhibition of the test organisms, viz. P. oryzae and R. solani were observed in all the treatments. Whereas, in the case of C. medinalis recommended doses of quinalphos in combination with ediphenphos and carbendazim and phosalone with tridemorph recorded highest mortality; while, highest dose of quinalphos with captafol and phosalone with ediphenphos were the superior combinations against N. lugens. From the above findings it could be concluded that, the fungicides viz. ediphenphos, carbendazim, captafol and tridemorph are compatible with all the four insecticides tried viz.; Phosphamidon, quinalphos, phosalone and monocrotophos in controlling the diseases, blast and sheath blight and insect pests leaffolder and brown planthopper.
Open Access
Effect of solarization on damping off diseases of vegetables
(Department of Plant Pathology, College of Horticulture, Vellanikkara, 1992) Sainamol Kurian, P; KAU; Peethambaran, C K
The effect of solarization on damping off of chilies caused by Pythium aphanidermatum was studied at the college of Horticulture, Vellanikkara, Trichur during 1991-92. For solarizing, 150 guage transparent polyethylene sheets were used. Both nursery and mainfields were inoculated with the fungus prior to solarization. Atmospheric temperature during the period of solarization ranged from 20°C to 38°C. The soil temperature in solarized plots was always higher (6°C-11.5°C) than the non solarized plots. Maximum soil temperature recorded at 10 cm depth i.n the solarized soil was 51°C while that in the non solarized soil was 42°C. Nursery beds were solarized for 15, 30 and 45 days while the main field was solarized for 35 days . Solarization effectively reduced pre and post emergence damping off in the nursery. In the main field, solarization completely checked the disease. As the period of solari.zation increased, better control of the disease was observed. Neemcake amendment did not improve the disease control even with solarization. The population of fungi, bacteria and actinomycetes were reduced as a result of solarization. The nematode population also was significantly reduced by solarization. Eventhough solarization substantially reduced weed population, its effect was more pronounced on dicots rather than monocots. Root colonization by VA Mycrrhizae was significantly better in solarized plots, compared to control. Growth parameters like, plant height, number of leaves, .shoot and root weight were increased through solarization. Plants grown in solarized plots gave 230% more yield over those in the control plots. However, neemcake amendment didnot favour either plant growth or yield. Availability of plant nutrients like P,K, Ca, and Mg was found to be better in solarized plots. Increase in organic carbon content and EC was also noticed in solarized plots. However, total N content of the soil was not altered by solarization.

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