Biocontrol of phytophthora blight of pepper employing Serratia plymuthica A21-4 and effect of soil population of Phytophthora capsici on the root colonization of the antagonistic bacteria
Park ChangSeuk; Shen ShunShan
Bulletin OILB/SROP 25(10): 327-330
A biological control agent, S. plymuthica A21-4, was selected from the roots of an onion plant. A21-4 significantly inhibited the mycelial growth, zoosporangial formation and cystospore germination of P. capsici in vitro. A21-4 showed 100 and 82.6% disease control efficiency in pot and greenhouse experiments, respectively. A21-4 readily colonized the root of pepper (Capsicum annuum cv. Nok-Kwang) and the bacteria moved to newly growing roots continuously. More than 106 cfu of A21-4/g of root is needed to protect pepper roots from infection of P. capsici in the soil. The colonization of pepper roots by A21-4 was influenced by the presence of P. capsici in the soil. When P. capsici was introduced in advance, the population density of A21-4 on pepper roots was sustained more than 106 cfu/g of root until 3 weeks after transplanting. On the other hand, in the absence of P. capsici, the population density of A21-4 was reduced continuously after transplanting and did not reach 105 cfu/g of root, but this phenomenon did not occur in the populations of A21-4 in soil.