Browsing by Author "Gunasekharan, M."

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    Coconut: Maladies and Remedies
    (2018) Rohini Iyer; Gunasekharan, M.; Vinayaka Hegde
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    Management of basal stem rot disease of Areca catechu L. in India
    (2004-04) Rohini Iyer; Parvathy Meera; Lekha, G.; Vinayaka Hegde; Gunasekharan, M.
    Basal stem rot caused by Ganoderma lucidum (Curtis Ex. Fr.) Karst is one of the dreaded diseases of arecanut. Pure cultures (16 nos.) of Ganoderma isolates were established from fruiting body, bark and root samples collected from Kerala, Karnataka, Tamil Nadu, Assam and West Bengal, the five areca growing states of India. Isolations made from the center of the fresh fruiting body were found to be better for obtaining pure cultures of Ganoderma. Standard aqueous leaf extracts of forty-three plant species were screened against the pathogen under b1 vitro conditions by poisoned food technique. Allium sativum extract completely inhibited the growth of the pathogen. Fresh leaf extract of Peperormia pellucida exerted 91.66 per cent inhibition followed by that of Clerodendron infortunatum (80.7%) and Musa paradisiaca (43.45%) at 96 h. Four fungal cultures viz., an unidentified sterile white fungus (77.8), Trichoderma harzianum( 72.2), T.viride (62.0). and Penicillium sp. (42.0) were found to be inhibitory on the mycelial growth of the pathogen at 96 h.
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    Stylet course of lace bug Stephanitis typica (Distant) in coconut leaf
    (1988-11) Mathen, K.; Radhakrishnan Nair, C.P.; Gunasekharan, M.; Govindankutty, M.P.; Solomon, J.J.
    The lace bug Stephanitis typica feeds on coconut leaflet from its abaxial side. It inserts its stylet through stomata and sucks the contents of the coconut foliage. Besides this intracellular feeding, the stylet also ruptures the walls of the cells traversed in its course to reach the vascular bundles. The stylet tip in such cases terminates in phloem, thereby suggesting the ability of the bug to acquire the phloem-bound mycoplasma-like organisms, constantly associated with coconut root (wilt) disease in India.
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    Stylet course of lace bug Stephanitis typica (Distant) in coconut leaf
    (1988) Mathen, K.; Radhakrishnan Nair, C.P.; Gunasekharan, M.; Govindankutty, M.P.; Solomon, J.J.
    The lace bug Stephanitis typica feeds on coconut leaflet from its abaxial side. It inserts its stylet through stomata and sucks the contents of the coconut foliage. Besides this intracellular feeding, the stylet also ruptures the walls of the cells traversed in its course to reach the vascular bundles. The stylet tip in such cases terminates in phloem, thereby suggesting the ability of the bug to acquire the phloem-bound mycoplasma-like organisms, constantly associated with coconut root (wilt) disease in India.
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    Transmission of root (wilt) disease to coconut seedlings through Stephanitis typica (Distant) (Heteroptera:Tingidae)
    (1990) Mathen, K.; Solomon, J.J.; Govindankutty, M.P.; Gunasekharan, M.; Sasikala, M.; Radhakrishnan Nair, C.P.; Rajan, P.
    Two-year-old West Coast Tall coconut seedlings obtained from a disease-free area were planted in methyl bromide-fumigated loamy sand collected from paddy field, held in field tanks and protected inside netted field cages. The seedlings were regularly inoculated with infective lace bugs, Stephanitis typica. Spear-loaf tissues of three of the four experimental seedlings gave strong positive serological reactions, indicating infection, nine months after the first inoculation. Root tissues treated with Dieness stain, DAPI and Hoechst 33258 fluorochromes indicated mycoplasma-like organisms (MLO) infection in the phloem. Serological and stain reactions in the fourth seedling were feeble at that time. Electron microscope examination of ultra thin sections of root apexes of all the seedlings revealed the presence of mycoplasma-like organisms in the sieve tubes. Of the four seedlings to which MLOs were transmitted by the tingids, two developed flaccidity of leaflets, the diagnostic and decisive symptom of the disease, eight months after infection was indicated by serodiagnosis. By the time the seedlings were visually identified as manifesting (he symptom of the disease, each seedling had received more than 1000 lace bugs with five days acquisition feeding on diseased palms known to harbour MLOs and about 1130 lace bugs with five days acquisition and thirteen days incubation. Control plants remained free of the organism and the symptoms of the disease.