Why are fungicides not recommended to control canker disease in home...

Asked September 5, 2016, 8:08 PM EDT

Why are fungicides not recommended to control canker disease in home blueberry plants per your article? I have ten blueberry plants in my back yard and several have what appears to be canker. My plants look like some of the photos of canker. We have indeed had a lot of wet weather this growing season and the problem only showed after the rains.

McCracken County Kentucky blueberries blueberry production blueberry diseases

4 Responses

I suggest that you submit a sample to the University of Kentucky Plant and Pest Diagnostic lab for confirmation. See: http://www2.ca.uky.edu/agcollege/plantpathology/extension/pdd_lab.html

I suspect that is Phomopsis or Botryosphaeria canker. Fungicide management of canker diseases is not easy. It is probably best to prune out infected shoots as soon as they appear and destroy them. Some protectant fungicides such as Captan can be somewhat effective, but they alone will not cure the problem.

Thanks for your reply, however that really did not answer my original question of, "Why are fungicides not recommended to control canker disease in home blueberry plants per your article?" If you would preface your answer with, "Fungicides are not recommended to control canker disease in home blueberry plants because..." , it would the be clear what the reason is. Please be specific as to the reason or reasons so that I clearly understand why I "should not try this at home". Thanks, Mike

As I stated, the fungicides are only "somewhat effective" and "they alone will not cure the problem." With canker diseases, sanitation is more important so without careful pruning out of infected canes and removing those from the planting, fungicides will not effectively control canker diseases. And you must know which disease you have to decide if to use fungicides, which fungicides to use and when. I suggest again that you send a sample to the UK lab for diagnosis. You may also want to refer the the Midwest Blueberry Production Guide. http://www2.ca.uky.edu/agcomm/pubs/ID/ID210/ID210.pdf especially pages 31-32 for a description of the canker diseases and suggestions for control.
You will find the comment: "Fungicides are ineffective for control of Botryosphaeria stem blight." If the disease is Phomopsis twig blight, then fungicide applications may be recommended.

Thanks for your prompt reply. That has more useful information. :)
Mike