Minnesota Bacteria, Viruses, and Other Pathogens

of Native Plants and Wild Animals

 

This is an unconventional grouping of organisms that cause disease in native plants or wild animals. It includes bacteria, viruses, oomycetes, viroids, virus-like organisms, and phytoplasmas. It does not include protozoa, which cannot be identified in the field; nematodes, which cannot be identified without uprooting and thus killing the plant; or parasitic plants, insects, and fungi, which are covered elsewhere.

 
Bacteria
 

 

 
Viruses
 

 

 
Other Pathogens
 

 

 

apical chlorosis of Canada thistle (Pst)

 

 

 

 

 

           
Recent Additions
     
Apical chlorosis of Canada thistle (Pst)
     

Visitors to Minnesota’s natural places will occasionally come across a stand of Canada thistle with a few plants that are whitened at the top, appearing bleached. The discoloration is caused by the bacterium Pseudomonas syringae pv. tagetis. It has been called “White‐colour Disease of Canadian Thistle,” “apical chlorosis of Canada thistle,” and “Bacterial Speck”, but it has no widely-accepted common name. It is often referred to in scientific literature as Pst.

Outside of a laboratory, a bacterium is recognized only by the symptoms it produces in its host. Pst 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. Pst infects plants in the Aster family, including Canada thistle, common dandelion, common sunflower, common ragweed, giant ragweed, Jerusalem artichoke, and some other plants not found in Minnesota.

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.

  apical chlorosis of Canada thistle (Pst)
   
   
   
   
   
   
   
   
     
Other Recent Additions
     

 

   

 

 

 

             

This list includes only pathogens that have been recorded in Minnesota, but not all of the pathogens found in Minnesota.

             
Profile Photo Video        
           

Pst

Profile Photo Video  

apical chlorosis of Canada thistle (Pst) (Pseudomonas syringae pv. tagetis)

 
       

aster yellows phytoplasma (AYP)

 
       

cottontail rabbit papillomavirus (CRPV) (Kappapapillomavirus 2)

 
       

fire blight (Erwinia amylovora)

 
       

 

   
       

 

   

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Created: 2/18/2020

Last Updated:

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