[nafex] Organic Brown Rot Control
scott at cs.jhu.edu
Fri Mar 23 12:41:45 EDT 2012
Caren, brown rot can be a challenge for organic growers. You need to attack it on every level possible.
1. Keep the tree healthy, well-mulched with organic matter, and regularly fed with foliar feeders such as seaweed and fish emulsion.
2. Prune the trees to be very open. Open trees let in more sun which kills the disease spores. To give an idea how open peaches can be pruned, look at the "after" picture on this link:
3. Regularly scout the trees for fruit with any sign of brown rot, and remove that fruit from the orchard. This may not be possible on large trees; its another reason to keep trees short!
4. Sprays that can be used include sulphur, Serenade, and Saf-T-Side oil (a mineral oil with disease smothering abilities - it is thick like yogurt). Don't just start spraying when you see the rot, do a delayed dormant (with lime-sulphur), a post-bloom, and then later cover sprays. Don't spray oil for two weeks after sulphur; sulphur can be sprayed 3-4 days after mineral oil since the oil should have all evaporated in that time. Of these three I have found sulphur to be the most effective, but none of them give strong control.
I have used this approach for several years now and while I generally do pretty well, I still have bad years on the susceptible varieties. Speaking of varieties, I have removed the most susceptible varieties, that is another important element of brown rot control. Your climate is not as severe as mine for diseases so you may be able to control it on your existing varieties.
On Mar 22, 2012, at 1:58 PM, Caren Kirk wrote:
> Last year I had brown rot on my cherries and plums for the first time.
> I had not had any experience of brown rot before, so it took me a awhile
> to identify it. However after doing so I was pretty meticulous about
> removing mummies and trying to keep the areas around the trees as clean
> as possible.
> Can anyone suggest the best organic methods for controlling brown rot?
> Last spring I just sprayed with dormant oil. I've heard sulfur can be
> I'd really like to keep it under control, not only for my cherries and
> plums but so it doesn't spread to my other stone fruit.
> Caren Kirk
> St. Jerome, QC
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