Studies on cercospora theae petch a causal organism of birds eye spot disease in tea plants

Abstract

Tea is one of the most common and cheapest beverages in the world. It is manufactured from the crop shoots comprising of two to three leaves and a bud of a perennial shrub Camellia sinensis (L) O. Kuntze. Tea plants are commercially grown in more than 60 countries, predominantly cultivated in Asian countries followed by African countries and to a very small extent in Europe, South America and Australia. Among the leaf diseases, bird s eye spot disease caused by Cercospora theae Petch is economically important, as it is highly prevalent in young and mature tea plantations Attempts were made to provide sufficient information on the pathogen nature in terms of morphology, physiology, biochemistry and molecular characterization of the pathogen namely C. theae. In this proposed study, various types of fungicides and biocontrol agents were screened under in vitro and evaluated against the disease under field conditions. The major outcome of the present study is that the pathogen C. theae was isolated from infected tea leaves collected from southern Indian tea plantations, which is the first authenticated report in India. Effect of biotic and abiotic factors on the pathogen were studied which revealed the growth of the pathogen was found to be more at pH 4.5, temperature 22ºC diffused day light room condition. Further, the ITS region were sequenced and donated to Genbank, NCBI, Bethesda, Maryland, United States and was provided with S. sannanensis formulated with vermicompost gave balanced results in terms of disease protection (53.9%), yield (3998 kg ha-1 made tea) and survivability (4x104 cfu per gram mother leaf). Silver and gold nanoparticles synthesized from these biocontrol agents were much more promising in terms of disease control and stability of antagonistic activity for a period of one year. It is therefore recommended to use vermicompost-based biopreparation containing biocontrol agents which could be explored extensively for the management of the bird s eye spot disease in tea estates. newline newline newline