The impact of the fungicide fenpropimorph (Corbel®) on bacterivorous and fungivorous protozoa in soil.
The ability of indigenous soil protozoa to survive and multiply after exposure to various concentrations of fenpropimorph was investigated. The average number of flagellate taxa detected declined with increasing fungicide concentrations. Naked amoebae and ciliates were present at all concentrations of fenpropimorph (0-60 mg/litre). Addition of glucose had a strong stimulatory effect on soil respiration, which lasted for about 20 d. Respiration in systems amended with glucose and pesticide was similar to glucose only. Bactiverous protozoa were affected at all concentrations. Higher concentrations of fenpropimorph impeded growth of the total protozoan population, whereas lower concentrations only affected heterotrophic flagellates. Bacterivorous protozoa were affected by fenpropimorph at concentrations lower than those expected in soil after normal field application, which may have detrimental side effects on soil nitrogen mineralization.