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nafex - Re: [NAFEX] Apple Scab

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  • To: "North American Fruit Explorers" <>
  • Subject: Re: [NAFEX] Apple Scab
  • Date: Sat, 31 May 2008 10:02:18 -0500

The only fungicides currently acceptable for use within most organic programs are elemental sulfur, lime sulfur, Bordeaux mixtures (copper plus lime), and basic copper sulfate.Sulfur is highly effective for control of powdery mildew. It is "at best" only fair for control of apple scab and summer diseases and provides minimal or no control of rusts. A major problem with the use of sulfur as a fungicide is the lack of residual protectant activity. Sulfur only provides about 3-5 days of protection without any rain washoff. When sulfurs were the only fungicides being used in the past, up to 25 applications per season were necessary to obtain satisfactory control.

It should be noted that sulfur is toxic to many beneficial insects, spiders and mites. These beneficial insects are natural predators of harmful insects and mites that affect fruit crops. Killing these beneficial insects may increase certain insect problems, especially with mites. Hope this helps.

----- Original Message -----
Sent: Friday, May 30, 2008 8:42 PM
Subject: Re: [NAFEX] Apple Scab

Dennis Norton wrote: 
I know that Ashmeads's Kernel is moderately susceptible to scab, but I'm not sure about Pitsmaston Pineapple.  If you had scab last season and did not remove the overwintering leaves or any mummies from the ground, you will definitely get scab this season.  Have you used any sprays for scab this season?
I religiously remove all fallen leaves and debris under the trees.  They sit on 9-foot-wide beds, heavily mulched with shredded cedar bark.  I'm an organic grower and do as little as possible to avoid spraying the fruit.  That's why I bag.  I use dormant oil and lime sulfur at pruning, need seed oil spray at pink bud and again at petal fall.  Other than a clean-up spray of neem seed oil in late autumn, that's all I do.  Despite the scab, the trees look very healthy and produce blemish-free, tasty fruit.  Is there something else I could spray that qualifies as organic?
Doreen Howard

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