A Study of Tar Spot of Coix lachryma-jobi L.in Thailand

Abstract

Job's tears (Coix lachryma-jobi L.) is an important millet-type cereal in Phayao and Chiang Rai provinces of North Thailand, and in the provinces of Chaiyaphum, Nakhon Ratchasima and Loei in Northeastern Thailand. Normally grown as a field crop, the grain is exported to Japan, Korea, Taiwan, Hong Kong, Malaysia and Singapore. In a survey of diseases undertaken in November 1983, the crop was found to be infected with the disease tar sprt, in the vicinity of Dong Ma Da village of Mae Suay district of Chiang Rai province. The symptoms were characterised by roughly circular raised black bodies (fungal stromata) about 1.5 mm in diameter, on the upper and lower leaf surfaces. The disease was estimated to have a more than 70 percent level of infection. The pathogen was identified as the fungus Phyllachora coicis. This respresents the first report of the occurrence of the disease tar spot in Job's tears in Thailand.