1. KAUTIR (Kerala Agricultural University Theses Information and Retrieval)

Permanent URI for this communityhttp://localhost:4000/handle/123456789/1

Browse

Subject: search.filters.subject.Pathogenicity

Search Results

Now showing 1 - 10 of 12
  • No Thumbnail Available
    Item
    Organic strategy for the management of sheath blight disease of rice
    (Department of Plant Pathology, College of Agriculture, Vellayani, 2017) Karthika, S R; Sajeena, A
  • No Thumbnail Available
    Item
    Distribution of species of phytophthora affecting coconut and pepper in Kerala
    (Department of Plant Pathology, College of Agriculture, Vellayani, 1996) Veena, S S; Peethambaran, C K
    The present investigation was undertaken to correctly identify the species of Phytophthora causing bud rot of coconut and foot rot of pepper in Kerala and to find out their comparative role in causing diseases on coconut and pepper. The study also aimed at isolation of viable antagonistic agents against the pathogen, so as to utilize them in future for biological control. The study was conducted during 1992-96 at College of Agriculture, Vellayani and Indian Institute of Spices Research, Kozhikode. Detailed symptomatology of both the diseases at different locations were studied. Periodic collections were made from diseased coconut and pepper from seven districts of Kerala. The morphological characters of the isolates were studied in detail. The length, breadth, L/B ratio, pedicel length and caducity of sporangia of coconut isolates were smaller than pepper isolates. The sporangial shapes differed considerably between and among the isolates. All the isolates except those collected from Kannur and Kasaragod districts (C7 - C16), produced abundant number of sporangia on carrot agar. Phytophthora are either heterothallic or homothallic. Generally P. palmivora and P. capsici are heterothallic. But ten coconut isolates obtained from Kannur and Kasaragodu districts produced abundant number of sexual structures on carrot agar, indicating their homothallic nature and this is the first report of homothallic Phytophthora causing bud rot of coconut in Kerala. All other 52 isolates were mated with known A1 and A2 mating type and all the coconut isolates produced oospores with A1 and all the pepper isolates produced oospores when mated with A2. Zoospore production was induced from sporangia using cold treatment. The number of zoospores in sporangia ranged from 6-15 in number. Chlamydlospore production was a rare phenomenon in pepper isolates while all the coconut isolates and five pepper isolates produced chlamydospores. All the isolates were inoculated into pepper seedlings, coconut leaves, tender coconut and coconut seedlings and the time required for infection, variation in symptom expression by different isolates etc. were studied. All the sixteen coconut isolates produced foot rot in pepper. Fourty six isolates of pepper produced lesions on coconut leaves and nut rot in tender coconut, while, only six isolates of pepper produced bud rot in coconut plants. The cross infectivity of pepper isolates needed further confirmation to prove the point beyond doubt. Eight cultivated plants, 9 ornamental plants and 12 weed plants were tested for the host range of coconut and pepper isolates. Many plants belonged to the above three groups took infection successfully. The microorganisms found associated with healthy and diseased pepper and coconut plantations and microorganisms from soils of pepper and coconut gardens of different parts of Kerala were isolated. Out of more than 200 microorganisms, only 28 fungi inhibited the growth of Phytophthora in vitro. On pepper plant, 12 isolates had inhibitory action. Three organisms, viz., Verticillium chlamydosporium, Aspergillus terreus and Chaetomium sp checked the pathogen completely even after seven days of spraying with the organisms.
  • No Thumbnail Available
    Item
    Epidemiology and control of sheath rot disease of rice
    (Department of Plant Pathology, College of Agriculture, Vellayani, 1986) Krishnakumaran Nair, B; Chandrasekharan Nair, M
    Studies on symptomatology, epidemiology and control aspects of sheath rot disease of rice caused by Serocladium oryzae Cams & Hawksworth (= Acrocylindrium oryzae Saw.) were done in detail. The disease initiated as purplish-brown oblong lesions on the sheath of the flag leaf. At maturity lesions enlarged in size with grey -white centres and often covered the entire flag leaf sheath. Panicle often did not emerge but choked inside the affected sheaf itself. Artificial inoculation studies showed that under sufficient humid conditions the pathogen took an average five to eight days for initiation and 15 to 20 days for the complete development of the disease in rice plants. The pathogen was isolated from four naturally infected rice varieties, collected from three different culture (isolates viz., S1, S2, S3, S4, S5, S6 & S7) were selected based mainly on symptomatological variations and their comperative morphological characters were studied in detail. No appreciable differences were noticed in the morphological characters between isolates.
  • No Thumbnail Available
    Item
    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; Chandrasekharan Nair, M
    Sheath 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.
  • No Thumbnail Available
    Item
    Triazole,strobilurin and its combination fungicides for the management of anthracnose and fruit rot of chilli
    (Department of Plant Pathology, College of Agriculture, Vellayani, 2018) Anjana, R S; Joy, M
  • No Thumbnail Available
    Item
    Etiology of honey bee brood disease in Southern Kerala
    (Department of Agricultural Entomology, College of Agriculture, Vellayani, 2018) Jyothis, P Joseph; Amritha, V S
  • No Thumbnail Available
    Item
    Integrated management of alternaria leaf spot of cabbage (Brassica oleracea var. capitata (L.))
    (Department of Plant Pathology, College of Agriculture, Vellayani, 2018) Madhu Kiran Gunda, V N S; Susha S Thara
  • No Thumbnail Available
    Item
    Response of selected okra [Abelmoschus esculentus (L.) Moench] cultivars to root knot nematode meloidogyne incognita (Kofoid and White)
    (Department of Agricultural Entomology, College of Horticulture, Vellanikkara, 2017) Chandini, S M; Susannamma Kurien
  • No Thumbnail Available
    Item
    Cataloguing, documentation and management of fungal diseases of strawberry (Fragaria x ananassa Duch.)
    (Department of Plant Pathology, College of Horticulture, Vellanikkara, 2017) Amrutha, P; Reshmy Vijayaraghavan
  • No Thumbnail Available
    Item
    Characterization and management of fungal pathogens of cabbage (Brassica oleracea var. capitata L.) and cauliflower (Brassica oleracea var. botrytis L)
    (Department of Plant Pathology, College of Horticulture, Vellanikkara, 2017) Nusrath Beegum, C H; Yamini Varma, C K