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nafex - [NAFEX] Spraying for scab with bagged apples

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  • From: Jason MacArthur <rotread@localnet.com>
  • To: nafex@lists.ibiblio.org
  • Subject: [NAFEX] Spraying for scab with bagged apples
  • Date: Sat, 3 Jun 2006 07:03:20 -0400

Nathan Torgerson wrote:
Dennis,
I have no experience with copper sprays, but from the little that I've read, copper applications aren't used after silver tip because it causes the fruit to russet if it's done later. I was guessing the russeting is caused because the copper is applied on the apples, but maybe that's a bad assumption, Do you know if there other reasons not to use copper applications throughout the summer?

Nathan, as I see it spraying copper now would be the wrong medicine applied at the wrong time. To be dealt with effectively, especially under an organic regime, scab has to be dealt with before it becomes established on your leaves, when less toxic materials than copper( i.e. Sulfur) can be used. Copper is a toxic and persistent material which will have effects on earthworms and soil life for many years after it is sprayed. I would think long and hard before using copper on a season long basis. Beyond that, I am not even sure how effective it is against secondary scab infections, and whether it is legal to use for this purpose.
My advice: keep your trees as heathy as you can this year by mulching, fertilizing, etc., and be prepared for apple scab in the spring when it is at it's weakest.

Jason MacArthur
Marlboro, Vt.





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