Determination of the efficacy of some biocontrol agents against Phytophthora capsici, the causal agent of root and crown rot in peppers

Root and crown rot or Phytophthora blight disease caused by P. capsici causes significant quality, yield and economic losses in pepper production areas of the country. It is hard or impossible to control this highly serious disease by using conventional fungicides. In this study, 12 different bacterial isolates belonging to different species were isolated from the soil and plants from Antalya region controlled and identified. The inhibitory and suppressive effects of these possible antagonistic bacterial isolates to P. capsici were determined in laboratory (in vitro) and in a climate chamber (in vivo) studies were determined. In the study, 3 different doses of Bacillus toyonensis, Enterobacter cloacae, Pseudomonas chlororaphis, Alcaligenes faecalis, Bacillus thuringiensis, Citrobacter freundii, Serratia fonticola, Achromobacter xylosoxidans, Bacillus cereus, Pseudomonas koreensis, Bacillus mojavensis, Lelliottia amnigena isolates were tested against the pathogen. In the laboratory assays conducted by using 2 different methods, the isolates of P. chlororaphis, C. freundii ve B. thuringiensis were found to be up to 70 % effective against P. capsici. In the growth chamber pot trials, the isolates of P.chlororaphis, A. faecalis, S. fonticola, L. amnigena, B. thuringiensis, C. freundii, B.cereus ve B.toyonensis were determined to be over 75 % effective to the pathogen. As a result, the bacterial isolates determined as possible antagonistic in both the laboratory and growth chamber assays in the study have high potential to be used as biocontrol agents against P.capsici in pepper production. These bacteria may be a efficient tools alternative to fungicides to control Phytophthora blight in pepper production.