Canopy Microenvironments and Applied Bacteria Population Dynamics in Shaded Tall Fescue

Abstract

Shading of the turfgrass canopy is assumed to support increased microbial activity and therefore more potential disease problems. The goal of this research was to determine how shading affects microenvironmental conditions, and how these conditions affect phylloplane colonization by applied bacterial strains. Shade cloth was suspended over tall fescue (Festuca arundinacea Schreb.) turf in field plots and environmental parameters were measured in shaded and full sun areas. Shading increased leaf wetness duration and relative humidity (RH), but decreased the average and range of canopy air and foliage temperatures. Three species of bacteria (Bacillus megaterium, Stenotrophomonas maltophilia, and Enterobacter cloacae) were applied to all plots. Populations of B. megaterium were the lowest of the three species in both study years. Data showed that measurable differences in microclimate occur as a result of shading and that bacterial colonization was generally favored by shading. The lack of consistency between the two assay methods and among bacterial species regarding the effects of shading suggests that differences in response to microclimate conditions may exist among bacterial species or strains. Results indicate that shading should be considered when screening biological control agents for disease management.