Suppression Effects on Pineapple Soil-Borne Pathogens by Crotalaria juncea, Dolomitic Lime and Plastic Mulch Cover on MD-2 Hybrid Cultivar

Abstract

The development and implementation of sustainable and environmentally friendly agricultural practices are indispensable as alternatives to pesticide use and to keep populations of soil-borne plant pathogens at levels that do not affect crop productivity. The present research evaluates the incidence of soil-borne phytopathogens on the pineapple variety MD-2, which was subjected to different treatments: Incorporation of <i>Crotalaria juncea</i> into the soil (organic amendment), application of dolomitic lime to soil (inorganic amendment), and the use of plastic mulch covering the soil. During the crop cycle (15 months), the following variables were evaluated: plant height (cm), fruit weight (kg·plant⁻¹ ), crop yield (ton·ha⁻¹ ), the bud root disease incidence caused by <i>Phytophthora nicotianae</i>, number of soil phytoparasitic nematodes and colony-forming-units (CFUs) of soil fungi and oomycetes. The results indicate that <i>Crotalaria juncea</i> treatment reduced the pathogen population (nematode and oomycetes) at levels that did not affect crop development, so that yield increased (18–20%). The incorporation of <i>C. juncea</i> into the soil as an organic amendment favors the populations of fungi disease suppressors (<i>Trichoderma-Aspergillus</i>). The phytoparasitic nematodes (<i>Meloidogyne</i> sp., <i>Pratylenchus</i> sp., and <i>Mesocriconema</i> sp.) and oomycetes (<i>Phytophthora</i> spp., and <i>Pythium</i> spp.) showed a reduction of their population levels by effects of organic amendment (<i>C. juncea</i>). The plastic mulch was also effective, probably due to the maintenance of optimal condition to crop growth and weed control. However, the dolomitic lime application had the poorest effect under the conditions of the study area on the variables analyzed. The described observations are characteristics of a system-based approach for the potential management of soil-borne pathogens of pineapple MD-2 in Veracruz, México.