Just what can I do to stop sooty blotch/fly speck? It has been another incredibly wet summer. We’ve had 9 inches in less than 2 weeks. No matter what, I’ve been plagued historically with sooty blotch. First try was w/Immunox–nothing, MFF–nothing, now Captan–better but still not good. Goldrush seems to be the most susceptible. I’ve tried to prevent it, but can it be killed once it’s on the fruit? Perhaps a mix of sulphur/Captan??
Lot of people just shrug and live with it
Or scrub it off
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Brook,
You probably have read this thread already. Just in case you haven’t.
What's the minimal spray program for Apple?.
What about opening up the trees for better via pruning including summer pruning? Have you thin your apples well?
If all else fails, you probably will need to find more effective way to scrub it off apples once harvested.
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The Midwest Fruit Tree Spray Guide lists several fungicides for sooty blotch and flyspeck. Propiconazole (MFF) and myclobutanil (immunox) aren’t among the AI’s listed as effective, so it is maybe not a surprise that those two products didn’t work for you. And it is good anecdotal evidence for the rest of us.
They list Captan + phosphorus acid as an effective combo. Pristine also, but that stuff is expensive…
I think that phosphorus acid is sold as a homeowner spray by someone. AgriFos, I think.
Thanks, all. Great links. Personally, I’m not at all bothered by the discoloration; however, I market farm and can’t offer up all that ugly fruit. It’s not as bad as in years past despite all the rain and humidity of this summer, so perhaps I just need to step up the Captan sprays. I also need to do more summer pruning. I always intend to but get distracted by all the other chores that seem to be more demanding.
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Pristine does a great job. It is expensive but if you can find people to go in with you it’s cheap because a little goes a long way
Do folks who bag with plastic bags have an issue with sooty blotch and fly speck? I bagged with nylon socks from GrowOrganic.com and since I picked my Zestar two weeks ago my Liberty have a raging case of sooty blotch.
No more than without
My worst sooty blotch was always on the yellow fruited tree I didn’t bag
Lois - Would you say about the same sooty blotch with plastic bags or slightly better?
I am trying to decide whether I should use those (sort of ugly to me) plastic bags next year or continue with the nylons. Or if I should consider adding a spray of sulfur or something synthetic. I know it is just cosmetic, but I’m a perfectionist.
I should add that sulfur is pretty strongly contraindicated for sooty blotch here. The late July - mid August period has too many days with temperatures over 85 or 90 degrees.
I produce pristine apples here in NY with an unorthodox method that Cornell suggests shouldn’t work. I don’t begin sprays until about July 7th for it and then use Flint or Indar or Pristine mixed with Captan in bi-weekly sprays until about the first week of Sept. At least one Cornell guru states that if you don’t spray in June the fungus gets established and can’t be helped but I’ve been doing this successfully for about 5 years now- including a couple of wet ones (especially wet Junes).
I used not to use Captan, but it seems to help for rots on Honeycrisp and probably is a good preventive to resistance development. Problem with using it exclusively is it needs reapplication immediately following heavy rain.
Goldrush is one of the varieties I protect, so it works on susceptible ones- I’m covering several scores of varieties in a few different orchards.
https://www2.ca.uky.edu/agcollege/plantpathology/ext_files/PPFShtml/PPFS-FR-T-15.pdf
This suggests to me that Topsin M may be your cheapest option. I may try including it next year.
Macozeb and its relations are inexpensive as well if the label permits its use through summer in your state.
Flint is probably overall your most effective affordable alternative because it is a systemic and won’t wash off. It’s not godawful expensive like Pristine either.
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I’ve never used sulfur so can’t speak to it - in fact I’ve never sprayed for sooty blotch
My own experience is that some varieties are more susceptible and that these tend to be the yellow varieties - on which it’s most visible. But the plastic bags don’t seem to make the problem worse or better
I don’t pay much attention to sooty blotch and flyspeck, when does it usually show up? Many years I think its not going to come and then one day there it is. So far this year I haven’t seen any of it. I used Indar for the first time on my apples this year and maybe that will help.
Thanks Alan. I appreciate your input.
I agree that your method could very well work here too, since I didn’t start seeing the effects until after about August 10th or so. We had a quite wet late June, July, and early August, but late May and the first week of June were dry here. So I guess my mileage could vary. We have dew every night all summer long as dewpoint limits our night-time temps all summer.
Boy… there isn’t an order of magnitude difference in price for that Flint vs. Pristine as there is between those two and Captan, Topsin M and phosphorus acid (to me this is phosphonic acid).
For whatever reason, Bonide sells a multipurpose fruit spray with the two AI’s of Pristine, but I don’t want/need the pyrethroid in August. https://www.amazon.com/Bonide-Fruit-Concentrate-Plant-Guard/dp/B00FGIPQYQ/ref=sr_1_1?ie=UTF8&qid=1472266475&sr=8-1&keywords=boscalid
Is there one of these fungicides that works for you for brown rot as well, so I can kill two fungi with one stone?
Scott - for me it showed up sometime between 8/7 and 8/20. There was very little to none on my Zestar and my Liberty had sooty blotch at least as early as last weekend. I’d say all of the unsprayed apples I’ve seen here have sooty blotch or flyspect to some extent.
Only Pristine, Indar and, of course, Captan. Pristine is two separate fungicides mixed.
The newer materials are still under patent so the companies are still pulling profits to pay themselves and for research and licensing. The evolution to safer and often more effective materials is financed by the growers.
I get the reason for the price and am ok with it. I would pay it if i could use the product in a couple years but it would probably go bad before I could get through it. Captan looks like it might be the most reasonable choice for me.
The Bonide product with Pristine’s A.I.'s would also work. I guess it would also have some effect on the Japanese beetles with the pyrethroid, so I wouldn’t be spraying insecticide for no reason at least.
Most pesticides last at least 4 years, although pyrethroids only last 2. Usually pesticides lose potency gradually, I believe. Most dry formulations probably last at least a decade if kept cool and dry (well wrapped).
Clearly the solution here is to expand my orchard operation. 