The influence of the heavy metals on the growth of pathogenic fungi

The reaction of the isolates of the pathogenic species Fusarium oxysporum Schlecht. and Pythium debaryanum (R. Hesse) Nieuwl. to the presence of zinc, copper, lead and cadmium, which were added to the nutritive medium for the determination of their in vitro tolerance, measured by the inhibition of the growth of mycelium were studied. The experiments were performed in the laboratory conditions by adding the suspension of the zinc, copper, lead, and cadmium in three different concentrations on the nutritive medium. The influence of the heavy metals on the growth rate of the pathogenic fungi depended on the type of metal and their concentration. The lowest degree of influence was exhibited by the presence of zinc, whereas the highest concentration of cadmium exhibited the highest degree of influence. Fusarium oxysporum, the mycelium of which grew considerably slowly in the presence of all metals, exhibited the lowest degree of tolerance to heavy metals, whereas even the lowest concentrations of Pythium debaryanum are tolerant to the presence of all metals, even in case of the highest concentrations.