Vinayaka Hegde

Molecular characterization of phytoplasma associated with phyllody of Pedalium murex - a common weed in coconut plantations

Phytoplasma belonging to subgroup 16SrII-A and identified as “Candidatus Phytoplasma australasiae”- was found constantly associated with phyllody of Pedalium murex, a common medicinal cum succulent weed in coconut ecosystem prevalent in South India. Infected P. murex showed stunted growth with reduced leaf size, shortened internodes and the characteristic transformation of floral parts into leafy structures typical to that of phytoplasma disease. This weed could possibly serve as a reservoir of sesamum phyllody in this region but no link with root (wilt) disease in coconut could be established based on molecular characterization studies. This is the first report of the association of 16SrII-A group phytoplasma with pedalium phyllody from the world.

In vitro screening of biological and chemical agents together on the growth of Colletotrichum gloeosporioides (Penz.) Penz. and Sacc. causing inflorescence die back in arecanut

Colletotrichum gloeosporioides is a destructive pathogen of many crop species causing diseases in many annual, biennial and perennial plants. A study was undertaken to find out the effect of biological and chemical agents together on the growth of C. gloeosporioides causing inflorescence die back in arecanut at the Department of Plant Pathology, CPCRI, Kasaragod. To reduce the release of chemical pesticides to the environment, integrated control strategies have been adopted extensively by combining both bioagents and chemical agents. So in the present study in vitro experiments were conducted with two compatible Trichoderma sp. viz., Trichoderma virens and Trichoderma viride and fungicides viz. Blitox 50 W and Mixol 72. The results indicated that all the treatments had a significant inhibitory effect on the growth of C. gloeosporioides and reduced its colony diameter. High percent inhibition was found when 0.05% of Mixol 72 was used with T. virens (87.61%). The least inhibition was shown by T. virens+0.05% Blitox 50 W (80.95%). It is concluded that the combination of bioagents with fungicides provided higher disease suppression than achieved with fungicides and bioagents when used alone.