Volume 17 Part 1 Article 44
Title: Studies on dry bubble disease caused by Verticillium fungicola
Authors: A. Shamshad, A. Clift and R. Butler
We report the results of a series of growing experiments examining the virulence or aggressiveness and fungicide susceptibility of four isolates of the mushroom pathogen Verticillium fungicola collected from mushroom farms near Sydney, Australia. The results of this work will be used to calibrate and interpret a quantitative polymerase chain reaction monitoring technique.
Three rates of inoculum, 105, 2 × 104 and 4 × 103 spores per m2, and two times of infection, at casing or at onset of pinning, were studied. Two fungicides, carbendazim and manganese (Mn) prochloraz, applied as split applications at fresh air and after first flush, were included. The rates applied were 1 and 1.5 g/m2 formulated product, respectively, at each application.
There was considerable variation in both fungicide susceptibility and virulence of the isolates. Losses due to infection varied between negligible up to 30%, depending on the rate and time of infection and the virulence of the isolate. The most virulent isolate was relatively susceptible to carbendazim. All the isolates were controlled by Mn prochloraz, but the most virulent isolate was the most difficult to manage with either fungicide. The farm this strain was isolated from was experiencing considerable difficulties in completely controlling this pathogen.
There is a clear need to continue monitoring both fungicide susceptibility to different fungicides and the virulence of pathogen isolates. Without this information, simply knowing the pathogen spore load is of limited value.