The disease progress of leaf blast (Pyricularia grisea) and chlorophyll leaf content in upland rice (Oryza sativa) were studied under direct drilling (DD) and conventional drilling (CD), in field experiments during 1998/1999 and 1999/2000. The apparent infection rates of leaf blast for CD and DD were b = 0.099 (r = 0,97**) and b = 0.666 (r = 0,90**) respectively, in the first growing season. In the second season, the rates for CD and DD were b = 0.054 (r = 0,99**) and b = 0.05 (r = 0,99**). However, there was no significant difference in the rates of leaf blast progress in these two tillage systems. A linear, positive and significant relationship was observed between the chlorophyll content of the leaf and leaf blast severity.
