Chili pepper (Capsicum annuum L.) is a vegetable
crop of economic importance in Thailand and during
the last few decades chili pepper production has
gradually decreased due to infection with various
diseases such as root and stem rot caused by
Sclerotium rolfsii Sacc., bacterial wilt caused by Ralstonia solanacearum (Smith) Yabuuchi et al.,anthracnose caused by Colletotrichum capsici (Syd.)
Butl. & Bisby., Fusarium wilt caused by Fusarium
oxysporum f. sp. lycopersici (Sacc.) Snyd. & Hans.
and root knot caused by Meloidogyne incognita
Kofoid & White. In southern Thailand, root
and stem rot (S. rolfsii) and bacterial wilt (R.
solanacearum) are very destructive diseases of chili
pepper. These diseases are very widespread, affecting
a large number of agricultural plants.
The plants attacked by these two diseases will rot,
wilt, and eventually die. Control of pathogens is
difficult because they attack plants from the soil, have
wide host range and survive in the soil for extended
periods. Chemical control was not effective as a
means to suppress these pathogens. Biological control
through the use of natural antagonistic microorganisms
emerged as an alternative disease management
strategy. Streptomyces spp. are one of the potential
biocontrol agents for plant diseases since they can
produce many secondary metabolites including
hydrolytic enzymes (glucanase, chitinase), herbicides
and a large number of antibiotics. Several species of Streptomyces
have been isolated and used to control plant
diseases such as Sclerotinia sclerotiorum (Lib.) de
Bary that cause sunflower head and stem rot, Rhizoctonia solani Kuhn
and S. rolfsii causing sugar beet damping-off and Pyricularia
oryzae Cavara and R. solani that are causing rice blast
and sheath blight disease,etc. This study was conducted to screen antagonistic
Streptomyces spp. for biological control of S. rolfsii
root and stem rot, and R. solanacearum wilt of chili
pepper.