Hemp Cover Cropping and Disease Suppression in Winter Wheat of the Dryland Pacific Northwest

The predominant cropping scheme for dryland wheat production in the Pacific Northwest (PNW) region of the United States includes winter wheat–summer fallow. Lack of crop diversification can deplete the soil organic matter and nutrients, while favoring the build-up of soilborne diseases. Cover crops are becoming more common within a standard rotation, primarily to provide protection against soil erosion, incorporate nutrients, and break soilborne diseases’ cycles. In this study, we investigated the potential of using hemp as a cover crop in a dryland wheat rotation to reduce soilborne diseases, and thus increase farmers’ profitability. While the benefits of barley and yellow mustard cover crops are well understood, the benefits of a hemp cover crop have not been examined in the PNW. We observed Fusarium spp. disease suppression on winter wheat following a hemp cover crop in the greenhouse studies. However, under field conditions, we did not observe a difference in pathogen abundance on winter wheat following hemp cover crop and hemp amendments in the field. Any potential to limit soilborne disease is a profitability opportunity for farmers. Our findings indicate that incorporating a hemp rotation into the PNW dryland wheat production system holds promise as a strategy to reduce soilborne diseases and improve soil health, though further research is necessary to confirm its effectiveness and underlying mechanism.