Reduction of Phytophthora capsici oospores viability by gases released during soil biosolarization of protected pepper crops in Southeastern Spain.

摘要

Phytophthora capsici is a soil fungus causing root rot in greenhouse pepper crops in southeastern Spain (Murcia and Alicante). Several factors determine soil biosolarization effectiveness to reduce pathogen inoculum in soil. The purpose of this study was to establish the effect uniquely attributable to gases released during biosolarization with fresh manure on P. capsici oospores viability. Oospores were incubated in laboratory at 20掳C inside vacutainer tubes that previously were put under vacuum and refilled with gases sampled from biosolarized field plots at different time intervals during the biosolarization period. The treatments consisted of different combinations of sampling time intervals (0-2-3-4-7-9-11-14-16-21-28 days, succession of days 9-11-14-21-28 and succession of all sampling days) and exposure times (6 to 34 days). The plots located within greenhouses were biosolarized with fresh sheep manure (7 kg m -2) during September and the length of the biosolarization period was 28 days. Oospores viability was determined with the plasmolysis method. Neither treatment completely eradicated the inoculum. Exposure to succession of gases collected during all sampling days was the most effective treatment in reducing inoculum viability, and significantly differed from control treatment (hermetic tubes with only air). The applied amendment dose and the soil temperature at 15 cm depth (daily maximum/minimum=36-45/33-40掳C) were effective to achieve the critical threshold which is required for generating a sufficient amount of volatiles that reduced the pathogen inoculum viability in the conditions of the experiment. CT VIII International Symposium on Chemical and Non-Chemical Soil and Substrate Disinfestation, Turin, Italy.