Crown Rust

(Puccinia coronata)

               
Conservation Status

IUCN Red List

not listed

Crown Rust

NatureServe

not listed

Minnesota

not listed

Occurrence

Widespread. Wherever wild or cultivated oats occur, except in very dry areas.

Season

Early May to September

Habitat/Hosts

common oat, wild oat, common buckthorn


Identification

This 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.

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.

 
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 spots contain 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.

 
Similar
Species

 


Distribution Distribution Map  

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


Comments

 


Taxonomy

Division:

Basidiomycota (club fungi)

 

Subdivision:

Pucciniomycotina

 

Class:

???

 

Subclass:

Pucciniomycetes

 

Order:

Pucciniales (rust fungi)

 

Family:

Pucciniaceae (a family of rust fungi)

 
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

Crown Rust of Barley

Crown Rust of Oats

Oat 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 oat 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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