Anaerobic soil disinfestation reduces survival and infectivity of Phytophthora nicotianae chlamydospores in pepper

Abstract

Phytophthora nicotianae is the principal causal agent of root and crown rot disease of pepper plants in Extremadura (western Spain), a spring-summer crop in this region. Preplant soil treatment by anaerobic soil disinfestation (ASD) may effectively control plant pathogens in many crop production systems, but field conditions and availability of C sources can limit its practical application. A laboratory experiment was conducted to study P. nicotianae control by ASD with low temperatures and several carbon (C) sources: rice bran, rapeseed cake, grape pomace and brewer’s spent grain. Survival and infectivity of pepper by P. nicotianae chlamydospores were reduced with all C sources assayed and redox potential in all ASD treatments indicated that reductive soil conditions were achieved. Rice bran (20tonsha−1); rapeseed cake (20tonsha−1), and grape pomace (40tonsha−1) were also assayed in a field experiment in early spring. Survival and infectivity of P. nicotianae were also reduced with all C sources. An increase of dehydrogenase and urease activities and a strong pH decline were observed with rice bran and rapeseed cake, probably related to an increase of anaerobic bacterial populations in soil. Application of ASD with high C source rates may be effective in control of P. nicotianae under low temperature conditions.