Photo by DATCP M. Wensing | Symptoms of Phytophthora austrocedri on juniper
According to the Department of Agriculture, Trade and Consumer Protection Nursery Program, last month, there was a detection of Cypress mortality detected in Wisconsin for the first time. The disease was causing damage to a field of ‘Star Power’ Juniper in a Washington County nursery. The oomycete plant pathogen Phytophthora austrocedri causes the disease.
Predominantly affecting plants in the Cupressaceae family, this pathogen was first reported in the United States in Oregon in 2024. Spreading of the pathogen occurs via infected plants, soil and water. Symptoms of infection with the disease include stunting, dull green or yellowish foliage in early infections, branch flagging and reddish brown/bronze foliage in advanced infections, lesions or cankers at the base of the plant or branch and orange/brown discolored wood tissue under bark from lesions or cankers.
Early detection of this pathogen is key. If you are a licensed nursery grower and suspect you may have plants infected with P. austrocedri, please contact DATCP’s nursery program at (608) 516-7617 or [email protected]. If you are a home gardener or horticulture professional and suspect you may have plants infected with P. austrocedri, contact the University of Wisconsin–Madison Plant Disease Diagnostic Clinic at (608) 262-2863 or [email protected].
