Any kind of acid,like vinegar,I use battery(sulfuric),is added to the tank.It helps the Captan to last longer,after being sprayed.It doesn’t have to be a lot.There is probably a chart or information somewhere.If found,I’ll post it here.
Okay,when using the search feature on this site and typing in the words “acidifying captan”,a number of posts came up.It might be best to know the pH of your water first,but I’d say adding about a half cup of vinegar to about two gallons of water,before mixing in the Captan,should be okay.
citric acid- probably about half a TBS per 25 gallons of water, depending on pH of water to begin with.
Olpea can give you more precise info and I would tend to trust it more than vinegar. It is quite inexpensive on-lne.
Why is that?
I like to use a paint mixing attachement on a drill and mix my water and surround in a 5 gallon bucket before transfering to my sprayer. I also have to continue shaking it every so often as my sprayer does not have an agitator.
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Just a hunch that it is more easily calibrated by the chemical consistency of the stuff. It’s also much more concentrated so when I’m on the road it doesn’t take up much space. I’m always cramped when I’m doing spraying rounds.
If Olpea would chime in, I think he could give a much better comparison of the two methods of acidification. He is the one who steered me to citric acid and he tends towards almost absolute precision, I believe.
I just add a TBS to 25 gallon tanks as I drive from one water source to another without bothering to check the pH of the water and this has yet to fail me. Maybe I would have gotten the same results with vinegar… I never tried it, which might be the main reason I prefer citric acid.
I used to use a chemical penetrant that serves a secondary function of acidification. Strong citrus odor to it although I assume the source of the scent is chemical.
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With Captan you need to make sure the spray water is acidic. At a pH of 8 half the Captan is destroyed in 10 minutes. A pH of 5 is ideal with 5-7 being ok if your going to spray right after you mix the Captan into the water. You can use vinegar or citric acid to lower the pH. I use citric acid which is found with canning supplies in retail stores. I use a 1/4 teaspoon of citric acid in 2 gallons of spray water. The amount needed will vary with the pH of your tap water. Buy some pH paper and use it to check pH. For more info on spray water pH take a look at this-
I’m using Brandt Lime Sulfur this year to try to help control apple scab, shothole and brown rot on peaches, and hopefully to suppress some insects. I mixed my first tank 12.8 oz per gallon, 10% dilution. I’m familiar with sulfur blue-ing the ground at hot springs etc, but the strong yellow coloring on the tree and blueing on the soil made me question my dilution. That’s all to be expected right?
Thats too much, usually it is 1/4 - 1/2c per gallon (2-4 oz). See the spray amounts guide:
I don’t think you will cause long-term damage if they were still dormant. But on any leaves that could cause a severe burn and I would hose things down.
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Thanks for your help Scott! I hadn’t seen the spray amounts guide before. I realize now that I used the amount that the label indicates for dormant stage control of shothole etc, 10-12% dilution (12.8 to 15.4 oz). I’m using percentage dilution as a reference since the Brandt lime sulfur label lists amounts in gallons product per 100 gallon tank
The label is confusing to me though - as it indicates 6-11% for delayed dormant control of mites/borers/aphids, and 7.5% sprayed at green tip for powdery mildew. Then it lists 0.75% to 1.5% at pre-bloom, early bloom, full-bloom for control of brown rot blossom blight. There are no leaves out, but flower buds are nearing first pink stage 
I’m hoping that didn’t damage the flower buds. I’ll hose it down to be safe I think.
2-4 oz per gallon would be 1.5-3% dilution. If a 7.5% dilution is recommended at green tip, then it seems like it should be ok on flower buds? But it sure seemed like too much to me visually.
That label seems off. I think it is for the 400 gallons per acre, they state 100-400 gallons but it seems more like 400 is what they mean? Here is a more normal label which looks like all the other ones I have seen
The products are all the same basically so there is not difference on that front.
I doubt there will be any issues at that higher concentration if leaves are not out.
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Can you tell me more about Milky Spore please? What is it? Where can I get it? How do I use it for Japanese Beetles? Is it Organic? Last year among other things I had Japanese Beetles eating my blackberries at harvest time.
Appreciate any help you all can offer!
John in Kentucky
It is a spore that infects the grubs in the soil. It is organic. Many places sell it, even my local garden center had it. If you apply it this year it will kick in for next year.
Here is a link with more details: Milky Spore Powder: Is It Effective? - Epic Gardening
I had noticed that label listed much different dilutions yet was a very similar product. Thanks for setting me straight, I’ll use the lower concentration next time 
Scott, thank you so much for this! I have read it over and over again.
It’s been 3-4 years now and I barely get any fruit from my Apple, Pear, Cherry, peach, plum and pluots, (just 5 peaches and handful cherries). Over the years, I have bought so many sprays, Bonide mostly. This season, Up to now, I have used dormant oil and copper and Spinosad powder. I am trying to figure out what to do next. I always seem to miss a step. I feel like I just want to use what I already have in my arsenal.
In the photo link you shared of the different stages of growth, They refer to stage three to four if I am not mistaken as green cluster. I think am at that stage right now.
Last night, I hit them all (and my roses) with one of the many sprays I own:
It smelled so bad. I am not sure I want to use it again! I really prefer to not mix my own Captan, I am terrible at fractions! I have a small hand sprayer which never translates well. Especially, when I have all these fruit sprays already. But I am being told, what I used is not nearly enough in strength.
What would you recommend I do now?
Would you recommend I try surround (which is (one I don’t own) when I see fruit? (Just a few flowers are starting. )Can I do anything now?
I definitely saw curio on peaches last summer. Leaf curl was another issue last year. Japanese beetles were all over my roses.
Somewhere I read that putting ashes at base would help stop curio and other destructive insects. I am trying that.
I am a big fan of Arbico and I have on order beneficial insects… I would hate to kill them. (Lacewings program and my personal favorite assassin bugs!) I have planted a garden just to attract beneficial insects and omnivore birds.
I have a tiny yard 6,000 square feet with 15 feet between me and my neighbors. I can’t be out there in a hazmat suit. People around here would go crazy if I am out there spraying in 6a Coastal Massachusetts! I need to be discreet.
I seriously would pay to have you devise my own spray program. Next to carrying around my huge heavy rubber black hoses around the yard, choosing and mixing sprays to use is my least favorite gardening chore.
Thank you so much for sharing all your knowledge!
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That spray has malathion in it which kills curc so it should work if you are applying it regularly from petal fall until the fruits are dime sized.
I don’t think beneficial insects work well in a small yard, they all fly off too fast. The malathion in your spray will also kill them.
I would try Surround from petal fall through mid-June, it should work well enough to give you some fruit and it is not toxic.
Also make sure to pay attention to the specific problems you have. For curc, Surround will work. For the beetles Surround also works. It is not clear if you have other problems or not. Including some Captan as well for disease control would probably be a good idea. If you have moths, then the spinosad should help but you need to spray it many times (something like six times over the season) from petal fall on.
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Scott, thanks for your well thought out and written response. I didn’t want to use something so toxic. I will try surround at petal fall.
I will try your other suggestions too.
I don’t think I have other issues as far as insects. Well aphids. But I am managing them.
The diseases are leaf curl and rust.
Thank you again! CC
Scott have you heard of the Bonide product " Fruit Tree & Plant Guard"? I have been using this one for some years with good success. It is a different chemical than Captan ( that smells horrible).
Yes I think that is the newer version of the Bonide spray above? All of these have general bug poisons in them which I don’t use so I don’t follow these sprays too carefully.
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I appreciate the info. I had used this for some years. I switched this year to something “organic”.
Hey Scott,
A few more questions for you on this Are you using Indar for brown rot in every tank of Surround? Roughly how many sprays of Indar do you do total in a season? I’ve seen a couple places recommending spraying for brown rot a month before harvest, but I have some new trees that I don’t really know when to expect their harvest. I had brown rot on the few Indian Free peaches I got last year, and the tree also has brown dieback at most pruning wounds which I think may be related. I’m planning to use Bonide Infuse for this purpose. I have given the tree one spray of Lime Sulfur early in the year, but not sure I want to do multiple rounds of it. In terms of the danger to the applicator it seems to me that a non-organic fungicide might actually be safer than the organic but highly caustic lime sulfur.
Regarding Spinosad vs Pyrethrin - am I understanding right that Spinosad mainly targets insects feeding on the sprayed tree and that’s why it’s lower impact vs Pyrethrin killing anything that might wander onto the sprayed tree (including beneficials coming to eat my pests)? I released a load of beneficials - assassin bugs, mantids, lacewings, and ladybugs - in my war on pest terror this year, and I am feeling tempted to use pyrethrin on stinkbugs and others that are coming in, but I imagine it could also be counter productive on the beneficials.
**I just read your comment re: beneficials not working well in small yards. That seems reasonable as I see very little of them after released. In my two year sample size, this year we seem to be doing a lot better on aphids attacking flowers at least. They started to show up on my lupines and a day later they were all gone. As for the bugs that affect my trees, not sure there’s any difference there.