North American Fruit Explorers mailing list at ibiblio

[<dmnorton@royaloakfarmorchard.com>]

Alan,

 

Fire blight can be a ballooning problem if not dealt with properly when it first emerges on certain cultivars. There are some cultivars that are much more prone to fire blight like Jonathan and Gala as well as the new Sansa, and some rootstocks more susceptible as well.  If you have the combination of variety and rootstock such as Jonathan on M7 or Gala on M111 it can balloon dramatically under the right conditions.  Even with spraying copper and strep,  last season we had a few blighted shoots on a few Gala on M7 stock in one row.  I noticed the symptoms early in the morning and before we could get out to prune them out, after noon we had a severe thunderstorm with 50 mile per hour winds out of the north.  The tree rows where the blight was ran east to west.  Within 10 days we had fire blight on 15 rows that followed a triangular pattern from north to south beginning with the northern most row where the first symptoms appeared.  It took 5 men 3 days to cut it all out along with 12 trees that were too far gone to save.  Fortunately, we had planned to remove 5 rows of those trees this past winter and replace them with the new Snow Sweet and Candy Crisp varieties.  In Michigan, where fire blight is resistant to strep, entire orchards have been wiped out in a matter of days.  Consider yourself very fortunate that you have had situations where damage was minor and never spread. 

    

Dennis Norton
Royal Oak Farm Orchard
http://www.royaloakfarmorchard.com
http://www.theorchardkeeper.blogspot.com
http://www.revivalhymn.com

----- Original Message -----

From: Alan Haigh

To: nafex@lists.ibiblio.org

Sent: Monday, April 07, 2008 5:41 PM

Subject: [NAFEX] fireblight

Dennis has been very helpful on clarifying the question I had about shoot blight but I have had experience that casts some doubt on what he said about fireblight necessarily being a ballooning problem once established in an orchard.  I manage several sites where I have had strikes on a single or a few trees, sometimes for several seasons, where the damage has been minor and never spread, even to nearby trees of the same cultivar.

 

I suspect that fireblight behaves somewhat differently in different regions.