Survival of Stenocarpella spp. in maize debris and soil suppressiveness to maize ear rot pathogens

Abstract: Stenocarpella species (S. maydis and S. macrospora) overwinter saprophytically in maize stubble but little is known about the factors that contribute to its survival and to the induction of suppressiveness of pathogen colonization. We aimed at determining the role of crop rotation on the survival of the pathogen and induction of specific or broad spectrum disease suppressivity. Maize fields cultivated with soybean crop rotation or maize monoculture were randomly sampled for Stenocarpella sp. detection. Stalks were sampled, DNA extracted and the pathogen quantified through qPCR. Soil from the same sampled sites was tested for suppressivity to F. graminearum, F. verticillioides and S. maydis. The crop rotation consistently contributed to the lowest Stenocarpella sp. quantification in maize stalks and also to the highest number of soils with suppressiveness to F. graminearum and F. verticillioides compared to the maize monoculture. The obtained data not only endorsed the importance of soybean crop rotation for broad spectrum control of stalk and ear rot causing pathogens but also pointed out the most promising fields to look for biocontrol agents once the suppressiveness is of biological nature.