Chile peppers are great to eat and also an important crop in Arizona. Production occurs primarily in southeastern Arizona, where favorable growing conditions exist. However, there is a disease of peppers called Phytophhtora blight that can occur and cause significant plant death and yield loss. The pathogen that causes this disease, Phytophthora capsici, resides in the soil and becomes active when soil is overly wet. Spread of the pathogen and disease development are related to the duration and intensity of summer rainfall events. Initial infection of plants occurs on roots and stems of plants at the soil surface. Successive rainfall events and sustained high levels of humidity lead to infections on the upper parts of plants, including leaves, stems, and pepper fruit. This pathogen is closely related to Phytophthora infestans, the organism responsible for the devastating Irish potato famine that occurred around 1850. Successful management of Phytophthora blight includes measures to minimize accumulation of excess water in pepper fields as well as preventative followed by additional applications of fungicides as long as favorable disease development conditions exist. Effective fungicides include Ridomil Gold, Revus, Presidio, Ranman, and others. Please contact me if more information is desired concerning Phytophthora blight and its management.

To contact Mike Matheron go to: matheron@ag.arizona.edu.

For questions or comments on any of the topics please contact Marco Pena at the Yuma Agricultural Center.
College of Agriculture, The University of Arizona, Tucson, AZ.