Effect of increasing doses of zinc in combination with organic materials on the occurrence of entomopathogenic fungi in the soil

The aim of the study was to determine the effect of zinc application in different doses with organic fertilization on the genera composition and the number of CFU (colony-forming units) of entomopathogenic fungi (EPF) in the soil. The experiment was carried out in greenhouse conditions. Soil samples for testing were collected in the third year of the experiment (spring, autumn), where the research objects were I – dose of zinc: control – lack (0) and 200, 400 and 600 mg Zn kg –1 of soil; II – no fertilization – 0 (CO), spent mushroom substrate (SMS), chicken (ChM) and cattle manure (CM). Entomopathogenic fungi were isolated using the method of isolation on a selective medium. In the course of the research, EPF of the genus: Beauveria, Metarhizium, Cordyceps and Lecanicillium were determined. The conducted research showed that entomopathogenic fungi of the Metarhizium genera formed the most CFU in spring. In the autumn there were three times less of them. Statistical analysis showed that the number of CFUs of the identified genus of fungi (on average) in soil samples significantly depended on the dose of zinc applied, organic fertilization and the genus of fungus, but only for Metarhizium spp.