Effect of soil moisture and temperature on survival of microbial control agents

Abstract

Microbial control of soil dwelling pests and pathogens depends on the survival of microbial inocula in soil Three microbes Beauveria bassiana A6 Serratia entomophila 626 and Pseudomonas fluorescens CHA0Rif were inoculated into soil microcosms at three soil moistures and temperatures Survival was determined at regular intervals Beauveria bassiana survived well in soil; after 3 months the populations were maintained at levels close to those immediately following inoculation under most soil conditions Serratia entomophila and P fluorescens populations declined gradually Soil moisture impacted on survival of P fluorescens with populations declining most rapidly in the dry soil at all temperatures Pseudomonas fluorescens was not recovered after 54 days at 20C The rate of population decline of S entomophila increased with soil temperature but populations remained above the minimum level of detection after three months with soil moisture having little effect on survival Formulation of S entomophila into granules greatly improved the survival of this bacterium in soil