The objective of the research was to find the hydrolyzed tannine compounds that can inhibit Xanthomonas sp. caused leaf spot disease on Chilli. The determination inhibited ability of hydrolyzed tannin compounds extracted from 4 plants (Bang leaves (Terminalia catappa), Eucalyptus leaves (Eucalyptus terticomis), Guava leaves (Psidium guajava) and Laksa leaves (Persicaria odorata)) in controlling Xanthomonas sp. under laboratory conditions with 5 replications. The results indicated that hydrolyzed tannine compounds extracted from Bang leaves have high effectively against Xanthomonas sp. with radius of inhibition zones reaches 3.7mm at 4 days after testing. The efficiency of 5 different concentrations (10%, 20%, 30%, 40% and 50%) of hydrolyzed tannine compounds extracted from Bang leaves in the nhibits bacterial growth and inhibits the increase population of Xanthomonas sp. under laboratory conditions with 5 replications. The results showed that hydrolyzed tannine compounds extracted from Bang leaves at 50% have high effectively against Xanthomonas sp. with the largest radius of inhibition zones was 2.8 mm and and the lowest log population was 7.21 cfu/ml at 4 days after treatment.

Keywords: Hydrolyzed tannine compounds, inhibits bacterial growth, inhibits the increase of bacterial population, leaf spot disease on Chilli, Xanthomonas sp.