Detection of Fungal Pathogens in the Environment

Abstract

The presence of fungal pathogens in the environment has to be detected and also quantified rapidly and precisely, because the inoculum for infection of crop plants comes from the pathogen propagules present in the soil, water, air and alternative host plant species. Soilborne pathogens may have different degrees of saprophytic ability, utilizing the organic matter present in the soil for their survival in the absence of crop plants. They produce different structures such as chlamydospores and sexual spores that are long-lived and are capable of surviving in the soil for several years. Fungal structures may be carried by irrigation water or rain water from one part of the field to other parts or to different fields. It has been ­possible to detect and identify the fungal pathogens in the irrigation water, recycled water used for growing hydroponic plants and also in wash water in the storage facilities for fruits and vegetables. The pathogens infecting aerial plant parts/organs are generally disseminated by wind to different locations. Traditionally spore traps have been used for assessing the spore load of air. Various biological, immunological and nucleic acid-based techniques have been employed for the detection, identification and quantification of pathogen propagules in the environment. Significant improvements have been made in the sensitivity and specificity of detection of fungal pathogens by applying immunoassys and nucleic acid-based methods that are capable of providing reproducible results rapidly and reliably. The relative usefulness and limitations of the detection techniques applied for the detection of fungal pathogens in the environment are discussed.