UC Cooperative Extension Ventura County
669 County Square Drive Suite 100
Ventura CA 93003
Monday - Thursday: 8 am to 5 pm
Friday: 8 am to noon or by appointment
Rust on Roses
Rose rust is caused by a fungus that infests the leaves of roses and causes the symptoms. Rose rust will cause defoliation of your rose bush and if the leaf drop is severe, it will in time affect the vigor of the bush and flower production.
The rust fungus lives year-round on the leaves of the rose either on the plant or on the dead leaf debris under the plant. In spring spores are produced, which are airborne to the new foliage and the disease cycle starts.
Rose cultivars differ in their susceptibility to rust. You may notice that certain areas of your yard may have environments that allow rust to thrive. Therefore, buy rust-resistant roses whenever possible.
To control rust, fungicides may be used. Several applications may be needed through the spring, summer and fall to keep rose rust damage to a minimum.