Crown Rust

(Puccinia coronata)

Conservation Status

IUCN Red List

not listed

NatureServe

not listed

Minnesota

not listed

 
Crown Rust
 
 
Description

Puccinia coronata is a fungal plant pathogen that requires two hosts to complete its life cycle. It has a broad primary (telial) host range, including more than 45 genera of grasses, and a narrow alternate (aecial) host range, mostly Rhamnus (buckthorns), but also Berchemia (supplejacks) and Elaeagnus (silverberries or oleasters). It is an economically important disease on cereals and grasses, including cultivated oats, barley, and rye.

Recent molecular studies suggest Puccinia coronata is a complex of seven species and two varieties. Each species and variety can be distinguished only on the primary host, and each is identified by that host. Collectively they are referred to by the common name Crown Rust.

On infected grass plants Crown Rust appears as light orange, pustule-like structures (uredinia) on the upper and lower leaf surfaces. It will occasionally also appear on leaf sheaths, culms (stems), the stalks of inflorescences (peduncles), and awns.

The uredinia are the fruiting structures of the fungus. They are round to oval and up to 3 16 long. They contain a dusty mass of thousands of microscopic, orangish-yellow summer spores (urediospores).

On common buckthorn Crown Rust first appears as swollen, yellowish-green spots on the upper leaf surfaces, leaf stalks (petioles), and twigs. Leaves and twigs are disfigured but the infection is not fatal to the plant.

 

Similar Species

 
Habitat and Hosts

More than 45 genera of grasses, including oat, barley, rye, quackgrass, slender wheatgrass, western wheatgrass, foxtail barley, and common buckthorn

Ecology

Season

Early May to September

 

Life Cycle

The life cycle of Crown Rust includes five stages and requires two host species to complete. The five stages are teleoispore, basidiospore, pycniospore, aeciospore, and urediospore.

First stage: Winter spores (teliospores), also called resting spores, overwinter on the remnants of infected wild grasses and on the residue of infected agricultural grasses left in the field.

Second stage: In the early spring, the teliospores germinate and produce summer spores (basidiospores). The basidiospores are wind blown up to a half mile. Some are eventually deposited on the upper leaf surface of young leaves of the alternate host, common buckthorn.

Third stage: In early May, bright yellow spots appear on the upper leaf surface. Each spot contains flask-shaped reproductive structures (pycnia) below and breaking through the upper leaf surface (epidermis) of the leaf. The pycnium is an aerial vegetative body made up of cluster of branching, receptive filaments (hyphae). The pycnium releases spores (pycniospores) in a thick, sweet liquid which attracts insects. The pycniospores are carried by insects or splashed by rain to the receptive hyphae of another nearby pycnium.

Fourth stage: The fertilized pycnia produces a raised, orangish-yellow “cluster-cup” (aecium) on the lower leaf surface. The aecium releases aeciospores which are carried on air currents.

Fifth stage: Aeciospores that land on an alternate host develop into a another kind of spore-producing body (uredium). Within 7 to 10 days asexual spores (urediospores) are formed and released. The urediospores are carried by gravity or wind to other plants and other parts of the same host plant. Generation after generation of urediospores are produced throughout the growing season, continually reinfecting the plant or crop. At the end of the growing season teliospores are produced and the cycle begins again.

Distribution

Distribution Map

 

Sources

7, 24, 26, 29, 30, 77.

Biodiversity occurrence data published by: Minnesota Biodiversity Atlas (accessed through the Minnesota Biodiversity Atlas Portal, bellatlas.umn.edu, 6/13/2025).

6/13/2025    
     

Occurrence

Widespread and very common

Taxonomy

Kingdom

Fungi (fungi)

Subkingdom

Dikarya

Phylum

Basidiomycota (club fungi)

Subphylum

Pucciniomycotina

Class

Pucciniomycetes

Order

Pucciniales (rust fungi)

Suborder

Uredinineae

Family

Pucciniaceae

Genus

Puccinia (orange-yellow rusts)

   

Subordinate Taxa

Puccinia coronata s.str

Puccinia coronata var. avenae (Oat Crown Rust)

Puccinia coronata var. avenae f. sp. avenae

Puccinia coronata var. avenae f. sp. graminicola

Puccinia coronata var. coronata

Puccinia coronati-agrostidis

Puccinia coronati-brevispora

Puccinia coronati-calamagrostidis.

Puccinia coronati-hordei

Puccinia coronati-japonica

Puccinia coronati-longispora

   

Synonyms

Aecidium catharticum

Aecidium crassatum

Aecidium crassum

Aecidium frangulae

Aecidium irregulare

Aecidium rhamnatum

Aecidium rhamni

Caeoma crassatum

Caeoma crassum

Caeoma rhamnatum

Dicaeoma gibberosum

Dicaeoma rhamni

Puccinia alpinae-coronata

Puccinia calamagrostidis

Puccinia calamagrostis

Puccinia coronata

Puccinia coronata f. agrostidis

Puccinia coronata f. agrostis

Puccinia coronata f. alopecuri

Puccinia coronata f. festucae

Puccinia coronata f. holci

Puccinia coronata var. alopecuri

Puccinia coronata var. arrhenatheri

Puccinia coronata var. avenae

Puccinia coronata var. bromi

Puccinia coronata var. elaeagni

Puccinia coronata var. epigejos

Puccinia coronata var. festucae

Puccinia coronata var. gibberosa

Puccinia coronata var. golestanica

Puccinia coronata var. himalensis

Puccinia coronata var. holci

Puccinia coronata var. hordei

Puccinia coronata var. intermedia

Puccinia coronata var. lolii

Puccinia coronata var. rangiferina

Puccinia coronata var. secalis

Puccinia coronata var. sertata

Puccinia coronati-hordei

Puccinia epigejos

Puccinia gibberosa

Puccinia lolii

Puccinia rangiferina

Puccinia rhamni

Solenodonta coronata

Solenodonta epigejos

Solenodonta gibberosa

Solenodonta rangiferina

 

   

Common Names

Crown Rust

 

 

 

 

 

 

Glossary

Awn

A stiff, bristle-like appendage at the tip of the glume, lemma, or palea of grass florets.

 

Culm

The hollow or pithy stem of a grass, sedge, or rush.

 

Peduncle

In angiosperms, the stalk of a single flower or a flower cluster; in club mosses, the stalk of a strobilus or a group of strobili.

 

Sheath

The lower part of the leaf that surrounds the stalk.

Visitor Photos
 

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Karen Starr

Crown Rust

We found this on a volunteer Hawthorne tree choking out one of our decorative bushes.

Greg Watson

Crown Rust   Crown Rust

Orange-Yellow Rust

I was hiking in Apple Blossom Overlook Park near La Crescent yesterday. I spotted the fungus on a Buckthorn. Don’t know the species of rust, probably Puccinia coronata var. avenae. A bit or research says that it also affects wheat and oat crops. Too bad, it would be great if it only hit Buckthorn.

MinnesotaSeasons.com Photos
Crown Rust   Crown Rust
     
Crown Rust   Crown Rust

 

Camera

Slideshows

Rez korunkatá - Puccinia coronata
Jiří Laštůvka - Kudláček

About

Published on Jul 17, 2012

No description available.

 

slideshow

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Other Videos

Oat leaf infected by Puccinia coronata
CUPlantPathPhotoLab

About

Published on Aug 17, 2012

We're looking at the surface of an oat leaf. The orange spots are developing masses of spores of the fungus Puccinia coronata, which causes Crown Rust. These rust-colored spores (urediniospores) become wind-borne and can cause new infections on oat leaves, and also a wide range of other grasses including barley. Not shown: the secret life of P. coronata on its alternate host, common buckthorn.

The video was taken over 5 days and 18 hours in our lab. This rust can make a bazillion microscopic spores in that time.

 

Camcorder

Visitor Sightings
 

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Simply email us at info@MinnesotaSeasons.com.
Be sure to include a location.

Karen Starr
6/12/2025

Location: Clinton Township, Michigan

We found this on a volunteer Hawthorne tree choking out one of our decorative bushes.

Crown Rust
Carrie Frank
6/11/2023

Location: 2427 Dallman Lane SE Rochester Mn 55904

please provide advice. Thank you.

John Valo
6/11/2023

Crown Rust disfigures the leaves and stems on which it is found. However, it is not fatal to the plant.

In some cities, Burnsville MN is one, the city encourages homeowners to pull up common buckthorn. Buckthorn is an undesirable, invasive, non-native plant that crowds out our native species. If your buckthorn has some crown rust on it, this may be a good time to get rid of it.

Greg Watson
6/6/2023

Location: Apple Blossom Overlook Park

I was hiking in Apple Blossom Overlook Park near La Crescent yesterday. I spotted the fungus on a Buckthorn. Don’t know the species of rust, probably Puccinia coronata var. avenae. A bit or research says that it also affects wheat and oat crops. Too bad, it would be great if it only hit Buckthorn.

Crown Rust
MinnesotaSeasons.com Sightings

 

 

Binoculars

 

Created: 6/12/2013

Last Updated:

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