Buckthorn Rust, Oat Crown Rust

Puccinia coronata

Key Features

  • Orange spots on upper leaf surface
  • Orange tubes on leaf underside
  • Orange tubes around stem
Little cups called aecia release spores that infect oats
Buckthorn rust
Buckthorn rust on stem. Photo by Milan Zubrik.


Oat-crown rust infects two hosts, oats and buckthorn. Most of the buckthorn infected are considered invasive pests and should be removed. There are different ornamental varieties with different degrees of disease susceptibility.


Overwintering spores (called teliospores) on infected oat straw germinate in the spring and produce basidiospores that infect young buckthorn leaves. These infections produce orange cups called aecia that infect oats. The lifecycle requires both hosts to complete the disease cycle.

Management Recommendations

Invasive buckthorn, Rhamnus cathartica, should be removed. Other buckthorn varieties may be more resistant to rust. Due to the invasive nature of buckthorns, no fungicides are recommended for the control of this disease.

Effective Pesticides

Active Ingredients include: Myclobutanil, Propiconazole

landscape report
Purdue Landscape Report
Plant & Pest Diagnostic Laboratory