I am positive it’s bacterial spot. I have had shot holes in the leaves, and the affected leaves looked identical to diseased specimen photos that I saw online.
In 2016 season, I used copper, which resulted in some phytotoxicity, but the trees stayed healthy afterwards till the end of the season. In 2015, I tried with Serenade, but it was almost useless, and I got serious defoliation from bacterial spot, so I had to apply copper, but it was after the fact and the fruits were already infected. Still, I was able to save the trees from a complete defoliation disaster. So this year, I decided to go back to copper and was debating whether I should combine it with tetracycline or not. I think the bottom line with copper is that it will cause a little bit of phytotoxicity, but it’s less impactful on the trees than leaving them unprotected. In addition, the fruits are not negatively affected by copper, only the leaves are (of course you need good foliage in order for the fruits to grow well).
I have had good luck with it I though rotate between propiconazole and Pyraclostrobin with Boscalid. These ladder two have a different mode of action. The brown rot is attacked from two fronts. I had zero rot last year. And isn’t Indar even better than propiconazole? Same mode of action as propiconazole. So using both makes no sense. My next move if I start seeing brown rot. Use Indar instead and alternate with Pyraclostrobin with Boscalid.
Indar is hard to get, propiconazole is easy to get in the Bonide formulation… I think Indar is better as I did better last year with it than I ever did before, but according to all the charts propiconazole has the same effectiveness.
Cool it’s working well, I would rather not use it, but will if needed.
What is the reduced rate for copper Scott? I am using Kocide 3000.
Thanks,
Richard
See our spray amounts guide 
It looks like 1tsp/gal there…
Thank-you, Scott. But may I ask another question of you and anyone else? Somehow I’ve wound up with pretty large quantities of both captan and myclobutanil. Almost $200 worth. So it would just kill me to turn around and have to buy a large quantity of propiconazole now…at least until I use more of the other two that I have. So my question is this: While neither one may be ideal, if you had to use only one of those 2, which do you think would be best for brown rot? Also, even if it would be somewhat wasteful and repetitive, what would do you think about mixing both together and using them to be sure I am covered for various diseases/fungi, etc? I did spray copper and captan at pink swell, btw. I’m about to spray gain now at petal fall (it rained every day during full bloom and I also didn’t want to hurt my bees, so nothing got sprayed in fill bloom. What do you think I should spray at petal fall? weakened copper? with captan or Myclobutanil? (if those are the only choice). Thanks so much.
Remember I was hit extremely hard with brown rot last year, and not much else (except insects, of course). I saw some peach leaf curl but not much. Thank-you all.
Make sure when you use captan to use acidic water. I use it on my strawberries before they bloom early in the year for gray mold. The first year I used tap water and it didn’t work at all. I was complaining about nothing else on the market for gray mold (Botrytis rot) on strawberries and Olpea suggested using acidic water and the captan worked like a charm. Appears not to work at all in neutral or basic water. Then i read the half life decreases in basic water. It changes the properties, and may even cause breakdown. Even in acidic water it’s not long acting.
PHI on strawberries is one day. I myself don’t use it during or past flowering.
Ho do you acidify the water? Vinegar or something else? How much do you add per gallon?
Yes vinegar, I remeasure every year, depends on your water. I shoot for 5.0 pH.
Everybody’s water is different, I’ll go test mine right now.
OK my water is over 8.0 pH I can’t measure it right now as the only test strips I have measure from 4.0 to 7.0 if anything is 7.0 it is too basic for me! I don’t need to know more than that. One tablespoon brought it down to 4.6, that works for me. It depends on how many carbonates are in your water. One tablespoon should be good for most people. Acetic acid only lasts about 2 weeks and it breaks down from bacteria. But that is fine for sprays. I use sulfuric acid for blueberries. I usually need very little too.
Make sure you add the vinegar before the captan!
Another alternative is to use rainwater. I usually only use rainwater, but I’m out right at the moment. I water my house plants all winter with rainwater. No deposits on the sides on my pots.
I read half life of many products is enhanced with acidic water, so I use it for all applications. Again most of the time I just use rainwater. My rainwater is 4.8 to 5.5. So no need to worry about the pH. One problem is getting clean rainwater at the start of the year and after long peroids of dry weather I have debris in the water. Dirt from the gutters, and roofing material too, i discard the first rain of the year. It’s decent after that.
Drew I must say thank you for that reminder. Last year I absolutely added vinegar to my water (I had the correct amount then so I need to look that up). But I had completely forgotten all about it this year- completely! That is one of my worst problems…a terrible memory. I learn things like that and then over winter when we go 7 months or so without using or thinking about fruit sprays, I forget it all! I know @Olpea and others here keep meticulous notes and I really need to do that. EVERYONE thinks they have a bad memory but mine truly is just awful. Anyway, thanks for the reminder. If anyone knows how much vinegar to add to a gallon of mixed captain I would appreciate that answer. Or, if someone has a better water acidifer that is as cheap AND AS EASY TO COME BY as vinegar, pls tell me that as well. Thanks all.
BTW, here are the chemicals I ordered a couple weeks ago and just received today! The EAGLE 20 EW brand/formulation of captan is very different from what i have used in the past- which was a wetable powder. I’m going to go look at the reference section on gf.org and hopefully I will find how much EAGLE 20EW per gallon to use at petal fall and shuck split…but if anyone knows I sure would appreciate that information. As usual, the label has it in amount PER ACRE. THANKS AGAIN.
Where do you buy sulfuric acid from? I have been adding vinegar to my blueberry water (also added sulfur to the soil) but it seems it is taking forever to get the soil to the right pH. Note that my blueberry plants are all potted.
Is that true for copper too? Do you add vinegar to water before mixing copper?
No, not with copper.
Yes, always exceptions, I never heard it helps or saw anything about copper and pH. Captan is unusual as mostly what benefits is insecticides. And yes always add water, vinegar, pesticide in that order. Moss likes acidic conditions so exception to everything. Lilacs like basic conditions, they probably would object to an acidic shower.
O’Reilly’s! 
Battery acid is 30% Sulfuric acid. Which is nice as it doesn’t burn that bad.
I need it to scarify seeds too, like blackberries when I’m growing from seed.
Battery acid is very clean as batteries tend to explode when contaminants enter the cell. Of course never use from an actual battery. I have a golf cart that has 6x 8 volt batteries as big as car batteries. They are a real pain, wish i had a gas cart! I could tow stuff too!
I’m noticing bacterial spot on my peach tree. No fruit on the tree now. I’m thinking about spraying with immunox now. Thoughts on this? Is there a point to it this late in the season? Will it prevent it for next year?
A fungicide is no use against a bacterial infection. I suggest copper. I’d wait until spring just because you will be spraying then anyway and you need to protect the trees not knock out the bacteria from the leaves currently infected, but fall does work for PLC so I’m not sure if it will be helpful or not. Search it up.
Thank you. I sprayed copper twice this spring. Kocide 3000. it’s better compared to past but still got holes in the leaves.
You can get a soap formulation and do a couple more sprays.
I went ahead and sprayed Bonide copper soap which is recommended for using during growing season. I had some leftover from last year. That’s the copper I started out with before I decided to buy Kocide since the forum mentions it a lot. Anyway, as I was wrapping up my spray I realized the holes may not be due to bacterial spot. It may have been copper injury! What I failed to mention (because I didn’t notice this before today) was that all the younger growth is clean. No holes. I was freaking out about bacterial spot that I think I sprayed Bonide copper some time in May/June. That may have caused the injury. I probably made it worse. Live n learn!