Crown Rust

(Puccinia coronata)

Conservation Status
Crown Rust
 
  IUCN Red List

not listed

 
  NatureServe

not listed

 
  Minnesota

not listed

 
           
           
           
 
Description
 
 

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

 
     
 
Biology
 
 

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

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

 
  6/9/2022      
         
 

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)  
       
 

Synonyms

 
 

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

 

 

 

 

 

 

 

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 stem.

 
 
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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

 
 
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