Survival of Pochonia chlamydosporia on the soil surface after different exposure intervals at ambient conditions.

Background: Exposure of the nematophagous fungus Pochonia chlamydosporia to solar radiation and elevated temperatures before being incorporated into the soil can reduce its survival and efficiency as biocontrol agent. Aims: A field experiment was carried out to assess the effect of the exposure period on the viability of P. chlamydosporia applied on the soil surface. Methods: A commercial bionematicide based on P. chlamydosporia was sprayed on soil, and soil samples were collected before and at 0, 30, 60, 90, 120, and 150 min after fungal application. Relative humidity (RH), the irradiance (IR), air temperature (AT), and soil temperature (ST) were recorded. The number of P. chlamydosporia colony forming units (CFUs) was evaluated after 20 days of incubation. Results: P. chlamydosporia survival decreased over the time of exposure on the soil surface. Overall, the number of CFUs decreased by more than 90% at 150 min after application. Exposure to RH >= 61%, ST and AT between 25-35 degrees C and 19-29 degrees C, and IR between 1172 and 2126 mu mol of photons m(-2) s(-1) induced a negative exponential effect on the survival of the fungus over the time. Conclusions: Exposure to climatic conditions on the soil surface reduces P. chlamydosporia viability. (C) 2017 Asociacion Espanola de Micologia. Published by Elsevier Espana, S.L.U. All rights reserved.