|SERRANO-PÉREZ, PAULA - Instituto De Investigaciones Agrarias Finca La Orden-Valdesequera
|DE SANTIAGO, ANA - Instituto De Investigaciones Agrarias Finca La Orden-Valdesequera
|DEL CARMEN RODRIGUEZ, MARÍA - Instituto De Investigaciones Agrarias Finca La Orden-Valdesequera
Submitted to: Scientia Horticulturae
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 12/5/2016
Publication Date: 12/15/2016
Citation: Serrano-Pérez, P., Rosskopf, E.N., De Santiago, A., Del Carmen Rodriguez, M. 2016. Anaerobic soil disinfestation reduces survival and infectivity of Phytophthora nicotianae chlamydospores in pepper. Scientia Horticulturae. 215:38-48. doi:10.1016/j.scienta.2016.12.003.
Interpretive Summary: The production of peppers for paprika in Spain takes place during the spring and summer. The timing of the season prevents the use of solarization or biosolarization due to the need to produce the crop during the same period as the solarization treatment would be most effective. The use of anaerobic soil disinfestation (ASD) has potential for use during periods where soil temperatures are cooler if the quantity of carbon (C) added is increased. Laboratory and field studies were conducted to determine if the principal pathogen of this crop, Phytophthora nicotianae, could be managed with the use of carbon application rates of 4 mg C per g of soil using multiple carbon sources. All of the ASD treatments were effective for decreasing the density of pathogen propagules and the infectivity of the remaining chlamydospores, the long-term survival structures of the pathogen. Increasing the rates of C further did not improve control. Application of the locally-available C sources of rice bran and rapeseed cake resulted in sharp, but temporary reductions in soil pH, indicative of changes in the microbial populations that were not seen when soil was autoclaved prior to ASD. This approach to soil disinfestation has potential for management of soilborne pathogens in regions where soil temperatures are not conducive to the use of soil solarization.
Technical 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 (20 tons ha-1); rapeseed cake (20 tons ha-1), and grape pomace (40 tons ha-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, potentially 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.