A Few Considerations

 

 

 

 

 
 
Sample should be representative of the problem in the field.
   
Sample should be fresh/recently infected.
   
Sample should be adequate in size.  How large?
   
Never collect dead plant samples! " Dead plants tell no tales!"
   
For leaf spot problem, usually about 20 leaves are adequate for the diagnosis procedures (microscopy, culture work, etc.)
  —
Large leaves with many spots will require fewer leaves for diagnosis than small leaves with fewer spots
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Whole plants are generally needed for all problems that are not leaf spots (e.g. wilt/blight problems)
   
Avoid plants that are obviously dead. Select plants that exhibit a range of symptoms, from mild to severe.
   
Useful materials/tools during sample collection: Essential Guidelines
 
 Wrap sample in clean and dry paper towels/newspaper.
   
 
 Do not add moisture!
   
 
 Place sample into a plastic bag to prevent desiccation.
   
 
 Sample must be kept fresh and in good condition.
   
 
 Samples to be mailed should be placed into a padded envelope or strong crush-proof box to prevent damage during transit.
   
 
 It is always best to mail a sample during the first part of the week, rather than late in the week when there is a risk that the sample will stay in transit for the weekend.
   
 
 Do not forget to fill-out the Disease Diagnosis Request Form!
 
Packaging of leaf sample/s with spots and blights
 
 
Packaging of leaf sample/s with suspected virus infection
 
 
Packaging of whole plant sample/s with wilting and stunting symptoms
 
 
An alternative way of sending virus-infected plant samples
 
Samples can be temporarily preserved using desiccants (calcium chloride/silica gel or beads)
 

 
References:
State Agricultural Response Team (SART), University of Florida

Windham Mark T. and Alan S. Windham. 2004. Plant Pathology Concepts and Laboratory Exercises. CRC Press, USA.