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  • From: Alan Haigh <alandhaigh@gmail.com>
  • To: nafex@lists.ibiblio.org
  • Subject: [NAFEX] controlling black knot
  • Date: Sat, 9 May 2009 17:10:39 -0400

I manage and grow a lot of highly black knot susceptible plums in my own nursery and on the many orchards I manage, so I have a lot of experience dealing with this scourge.  During the growing season I usually have a strong bladed pocket knife with me so I can cut out galls whenever I see them on plums in my nursery and orchards I manage.  I don't actually cut back too far beyond the galls themselves unless discolored wood extends much beyond. I don't do anything to disinfect between cuts anymore and won't until someone shows me evidence that the extra time will pay adequate dividends.  Just didn't seem to help much in my anecdotal experience.
 
I used to spray all the cuts with Bravo but I'm not sure that was very helpful either.  What really seems to matter is just keeping up with it as much as possible and to remove all the black-knot you can on several occasions during the growing season and then thoroughly cleaning up during dormancy.  While it's also useful to eliminate wild cherries I have clients with such trees loaded with galls standing right next to plums I've planted that haven't seemed to exacerbate the problem much.
 
In addition to the knife with a tanto blade I  use my pruning shears and Silky Gomtaro 300 pruning saw which all help me to remove these things.  Spring has been wet lately so diligence is required.  I've never lost a plum to this disease in 20 years but I've sure lost a  few branches.  It's a good reason to keep plums growing vigorously.  Methely is the most susceptible plum to black knot I know and the Japs in general are more susceptible than Euros.  Italian plum hardly gets it at all.


  • [NAFEX] controlling black knot, Alan Haigh, 05/09/2009

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