Biocontrol of Late Blight Disease (<i><scp>P</scp>hytophthora capsici</i>) of Pepper and the Plant Growth Promotion by<i><scp>P</scp>aenibacillus ehimensis</i><scp>KWN</scp>38

Abstract

Abstract For field application of a bacterial strain used to control P hythophthora capsici , we will need a biologically and economically efficient carrier medium. The known antagonist P aenibacillus ehimensis KWN 38 was grown in a grass medium where it showed high antifungal and lytic enzyme activities. To demonstrate the potential of P . ehimensis KWN 38 for biocontrol of late blight disease in pepper, pot trials were conducted by treating the 1‐month‐old plants with water ( W ), a selected grass medium ( G 3), G plus P . ehimensis KWN 38 inoculation ( G 3 P ) or synthetic fungicide ( F ). The shoot dry weight in G 3 P was higher than that in W and F treatments at 15 days after zoospore infection ( DZI ). The root dry weight in G 3 P was also higher than that in W . The root mortality of G 3 and W increased over 58 and 80% at 15 DZI, and some plants in those treatments wilted due to the failure of root physiology. The plants in G 3 P and F survived well because of their better root health conditions. Soil cellulase activity of G 3 P was consistently higher than that of W and F at earlier observation times (0, 2 and 6 DZI). The root β ‐1,3‐glucanase activity of G 3 P promptly increased to maximum shortly after zoospore infection and reached the maximum value of 51.12 unit g −1 of fresh weight at 2 DZI. All these results indicate that inoculation of P . ehimensis KWN 38 to the root zone of potted pepper plants increases plant growth, root and soil enzyme activities and alleviates the root death caused by infection with P . capsici zoospores.