Crown Rust

(Puccinia coronata)

Conservation Status
Crown Rust
  IUCN Red List

not listed


not listed


not listed


Puccinia coronata is a fungus that affects wild and cultivated oats, barley, rye, and a number of other grasses. There are many varieties and all are species specific for their grass host but all use common buckthorn as their alternate host. The variety can only be distinguished on the grass host, and is identified by that host. Collectively they are referred to by the common name Crown Rust. Two well known varieties are Oat Crown Rust (Puccinia coronata var. avenae) and Barley Crown Rust (Puccinia coronata var. hordei).

On infected grass plants it 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 it 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

Cultivated oat, barley, and rye; wild grasses including quackgrass, slender wheatgrass, western wheatgrass, foxtail barley, and several wheatgrasses and wild rye grasses; and common buckthorn




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 Map



4, 7, 24, 26, 29, 30.




Widespread. and very common

  Kingdom Fungi (fungi)  
  Subkingdom Dikarya  
  Phylum Basidiomycota (club fungi)  
  Subphylum Pucciniomycotina  
  Class Pucciniomycetes  


Pucciniales (rust fungi)  






Puccinia (orange-yellow rusts)  



Aecidium crassum

Aecidium rhamni

Puccinia calamagrostidis

Puccinia coronata f. agrostidis

Puccinia coronata f.sp. alopecuri

Puccinia coronata f.sp. avenae

Puccinia coronata f.sp. festucae

Puccinia coronata f.sp. holci

Puccinia coronata f.sp. lolii

Puccinia coronata var. arrhenatheri

Puccinia coronata var. calamagrostis

Puccinia coronata var. festucae

Puccinia coronata var. holci

Puccinia coronata var. lolii

Puccinia lolii

Puccinia rhamni

Solenodonta coronata


Common Names


Crown Rust










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



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



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.



The lower part of the leaf that surrounds the stalk.

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    Crown Rust   Crown Rust  
    Crown Rust   Crown Rust  



Rez korunkatá - Puccinia coronata
Jiří Laštůvka - Kudláček

Published on Jul 17, 2012

No description available.




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Other Videos
  Oat leaf infected by Puccinia coronata

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.




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