Effect of traditional and new agricultural practices on pathogen andbiological control agents populations and on soil suppressiveness

Abstract: By 2050, there will be 9 billion people on earth to feed using the same amount or lessland and water as is currently available for agricultural production. Currently about one third ofall agricultural commodities grown worldwide are lost to diseases, insects and other pests.Soilborne diseases account for a significant amount of those annual losses in food production,and crop plants often lack resistance to soilborne pathogens. Farmers will need to increaseproduction, but must do so using less pesticides and more sustainable cropping practices. Thispaper discusses how changes in agricultural practices that are needed to enhance sustainability in21st century wheat production also impact populations of soilborne pathogens and diseases,disease suppressive soils and populations of biocontrol agents. We focus on the PacificNorthwest of the USA, and more specifically on wheat production in the state of Washington.Changes to more sustainable agricultural practices such as reduced tillage have led to an increasein the incidence of soilborne diseases but new agricultural practices as well as techniques inprecision agriculture and molecular detection of soilborne pathogens are finding solutions todisease problems. Indigenous biocontrol Pseudomonas spp. such as those producing 2,4-diacetylphloroglucinol and phenazine-1-carboxylic acid have a role in natural suppression ofdisease, but their populations and role in disease suppression are also affected by changes inagricultural practices.