Compatibility of plant growth promoting rhizobacterial strains with agrichemicals applied to seed
The compatibility of a select group of plant growth promoting rhizobacterial strains with chemicals commonly used as seed treatments was investigated. Strains in several genera (Serratia, Pseudomonas, and coryneform-like bacteria) were found to be tolerant to Vitavax RS (containing lindane, carboxin, and thiram), Epic (iprodione), and (or) captan tested in vitro at commercial rates. Six of 10 strains survived equally, and exhibited similar root colonization, on Vitavax RS treated and nontreated seed. Four of seven strains tested (Serratia spp. and P. fluorescens) were likewise found to be compatible with a captan seed treatment on supersweet corn, using the same criteria. Ability of bacteria to grow on pesticide-amended media did not always indicate compatibility with chemical seed treatments in vivo. A greenhouse study demonstrated that enhanced emergence occurred with the coryneform-like strain 44-9 on Vitavax RS treated canola seed grown under conditions favoring disease due to Rhizoctonia solani. The ability to combine plant growth promoting rhizobacterial strains with current agrichemicals for plant growth stimulation and disease control is indicated. Key words: pesticide compatibility, Pseudomonas, agrichemicals, Serratia, damping-off, plant growth promoting rhizobacteria.