ABSTRACT

This chapter is divided into methods for: estimating inoculum of soilborne pathogens; estimating inoculum of airborne pathogens; and detecting seedborne inoculum. Measuring the quantity of pathogen inoculum can help determine disease intensity and severity, and control measures to be used. The fungus can be detected on medium 182. Medium 257 gives good results with soils that do not contain fast-growing fungi such as Mucor or Rhizopus. Culture filtrates of Fusarium inhibit growth of Fusaria other than those from which the filtrate was obtained as well as other fungi. Soil pellet or soil dilution method can be used for detection and enumeration of Laetisaria arvalis fungus on medium 200. The bacterium can be characterized on media 289 and 290. Medium 263 eliminates gram-positive bacteria, some saprophytic Bradyrhizobium and Pseudomonas. The bacterium also can be detected and estimated by the bacteriocin technique.