Factors influencing spore germination, appressoria formation and disease development in Camellia sinensis by Glomerella cingulata
1995
Chakraborty, U. | Das, G. | Chakraborty, B.N. (University of North Bengal, Darjeeling (India). Dept. of Botany)
Factors associated with conidial germination and appressoria formation of Glomerella cingulata causing the brown blight disease of tea (Camellia sinensis) were studied in vitro. Spore germination and appressoria formation were optimum at a temperature of 25 degrees C, pH 5.0, 7 h light/day regime and a 24-h incubation period. At a concentration of conidia of 1200/microL 10-d-old culture, G. cingulata exhibited a maximum germination and appressoria formation. A maximum production of lesions was also evident on detached tea leaves at this spore concentration and in diffuse light. Diffusates of a phenolic nature collected from tea varieties susceptible and resistant to G. cingulata inhibited spore germination and appressoria formation. Diffusates from resistant varieties were more fungitoxic than those from susceptible varieties. Some phenolics known to be present in tea leaves, when tested in vitro, exhibited varying degrees of fungitoxicity. Pyrogallol totally inhibited spore germination, while pyrocatechol and phloroglucinol completely inhibited appressoria formation.
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