Evaluation of Spinach Cultivars for Downy Mildew Resistance in Yuma, AZ, 2023

Numerous hybrid spinach cultivars are released annually by commercial seed companies. These novel cultivars typically include a combination of known or new resistance genes to the pathogen of downy mildew disease, Peronospora effusa. Annual sentinel plots provide an insight into how the cultivars perform under field conditions with naturally occurring endemic inoculum of P. effusa. A field evaluation of resistance to the downy mildew pathogen of spinach was conducted in Yuma, AZ, in 2023. Disease development was due to naturally occurring inoculum. The disease incidence (DI) was recorded 57 days after the wet date for 70 cultivars. The DI varied considerably among the cultivars tested, and the range was 0.0 to 98.3% infected leaves.