Culture-independent detection and quantification of Fusarium circinatum in a pine-producing seedling nursery

Abstract

The primary symptoms associated with Fusarium circinatum infection in pine seedling nurseries are root and collar rot, shoot and tip die-back and seedling mortality. Management of this pathogen in nurseries usually involves the integration of various strategies relating to sanitation, insect control and fungicide treatment. The overall goal of this study was to use quantitative real-time PCR (qPCR) to detect and quantify the airborne inoculum of F. circinatum in a commercial pine seedling nursery. For this purpose, an existing qPCR method was optimised and evaluated for its efficacy to quantify and monitor airborne conidia over a one-year period. Results showed that F. circinatum occurred at relatively low levels in the nursery throughout the year and that its distribution was spatially sporadic. The data suggest that standard nursery sanitation practices in the test nursery maintained the airborne inoculum of F. circinatum at low levels. The uneven distribution of infection also suggests that airborne inoculum does not represent the primary source of inoculum for the F. circinatum-associated seedling disease.