apical chlorosis of Canada thistle (Pst)

(Pseudomonas syringae pv. tagetis)

Conservation Status
apical chlorosis of Canada thistle (Pst)
  IUCN Red List

not listed

     
  NatureServe

not listed

     
  Minnesota

not listed

     
           
           
           
           
           
           
           
 
Description
 
 

Outside of a laboratory, a bacterium is recognized only by the symptoms it produces in its host. Apical chlorosis of Canada thistle (Pst) (Pseudomonas syringae pv. tagetis) is a bacterium that infects some plants in the aster (Asteraceae) family. It produces the substance tagetitoxin, which blocks the production of chloroplasts, preventing photosynthesis. This results in whitened plant growth (chlorosis) on only the upper portion of the plant, stunted growth, fewer shoots, and inhibition of flowering.

 
     
 

Similar Species

 
     
     
 
Hosts
 
 

Plants in the Aster (Asteraceae) family, including Canada thistle, common dandelion, common sunflower, common ragweed, giant ragweed, and Jerusalem artichoke.

 
     
 
Biology
 
 

Season

 
 

Symptoms most noticeable from June to September

 
     
 
Use
 
 

Researchers at the University of Minnesota conducted a study in 2002 to assess the viability of using Pst as a biological control agent for Canada thistle.

 
     
 
Distribution
 
 

Distribution Map

 

Sources

7, 26, 30.

 
  9/4/2020      
         
 

Occurrence

 
 

Common

 
         
 
Taxonomy
 
  Phylum Proteobacteria  
  Class Gammaproteobacteria  
 

Order

Pseudomonadales  
 

Family

Pseudomonadaceae  
 

Genus

Pseudomonas  
       
 

Synonyms

 
 

 

 
       
 

Common Names

 
 

apical chlorosis of Canada thistle

bacterial speck

PST

white‐colour disease of Canadian thistle (UK)

 
       

 

 

 

 

 

 

 
 
Visitor Photos
 
           
 

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MinnesotaSeasons.com Photos
 
 

Pst on Canada thistle

 
    apical chlorosis of Canada thistle (Pst)   apical chlorosis of Canada thistle (Pst)  
           
    apical chlorosis of Canada thistle (Pst)   apical chlorosis of Canada thistle (Pst)  
           

 

Camera

     
 
Slideshows
 
 
     
     
     

 

slideshow

       
 
Visitor Videos
 
       
 

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Created: 4/12/2018

Last Updated:

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