The objective of this study was to screen
Streptomyces spp. for biological control of root and
stem rot (Sclerotium rolfsii) and bacterial wilt
(Ralstonia solanacearum), the very destructive diseases
of chili pepper in Thailand. About 265 isolates
of Streptomyces spp. were tested for their inhibitory
effects on S. rolfsii mycelial growth on dual culture
plates. Then, 14 promising isolates were further
tested for their effects on R. solanacearum growth.
Three effective isolates further identified as S. mycarofaciens
SS-2-243, S.philanthi RL-1-178 and S. philanthi
RM-1-138 were selected and proved to produce
both antifungal and antibacterial substances in the
culture medium. S. philanthi RM-1-138 strongly
inhibited seed germination and seedling growth of
chili pepper in laboratory tests. Therefore, it was not
used in the following studies. When tested in
greenhouse conditions, the efficacy of S. philanthi