Investigation and Prevention of Leaf Spot in Radix Pseudoxtellariae in Southeast State of Guizhou Province

[ Objective] The paper was to isolate the pathogen of leaf spot in Radix pseudoxtellariae, and to select the best fungicide with good antibacterial effectagainst the disease. [ Method] The pathogen was isolated from the diseased leaves, and the antibacterial activities of four fungicides including carbendazim, chlorothalonil, thiophanate-methyl and mancozeb against the pathogen were measured through mycelial growth method. [ Result ] The microscopic examination resultsshowed that the main pathogens of leaf spot in R. pseudoxtellariae were Phyllosticta commonsii and Alternaria sp.. Antibacterial results showed that four fungicidesall had apparent inhibition effect against leaf spot in R. pseztdoxtellariae, of which carbendazim had the best effect with the inhibition rate of 76.6% ; followed bythiophanate-methyl with the inhibition rate of 72.3% ; the third was mancozeb with the inhibition rate of 68.7%, and the inhibition rate of chlorothalonil was the