I’m thinking I may need to use captan or some fungicide for the first time this year. I had shothole show up last season on my nectarines. I got most of them copper sprayed recently but I’m thinking it may be a good idea to use a fungicide in some of my early sprays. Iv’e read a number of threads here about captan and I have a couple of questions. I noticed several refrences to captan burn. What causes this? Are people applying too much or is it a timing issue or another reason? Also I think I remember reading something about the water needing to be a certain ph but I couldn’t find it in the searches I did. Am I remembering this correctly? Thanks.
Which Captan are you referring to? Enter “captan” in this label database to see the various products:
I don’t think Captan is very good for shot-hole. Look up in one of the pesticide guides to find the right spray for your disease. Copper is much better for shot-hole, spray at pink in spring and right after leaf fall in late fall. You can also spray copper before shuck split. Chlorothalonil is another good product for shot-hole, it has a 60-day PHI so its similar to copper in that it can go down when there are leaves but not too far into the season. Olpea is the expert here on shot-hole so hopefully he will chime in as well.
I mostly use the stuff on strawberries, against botrytis mold
I knew there were several formulations. I’ll need to research this further. Thanks for the link.
Good to know Scott. I should say that I think what I had was coryneum blight so fungal shot-hole. I didn’t realize captan was weak on that. Most of my trees were just got sprayed with copper and oil however I didn’t spray one because I sort of screwed myself. The darn thing wouldn’t lose its leaves because it has been so warm and I kept waiting and waiting. I went away for a few days and bam lots of open flowers already. I am thinking I will spray that one tree with copper soap that I have because it is labeled for spraying through the bloom and even with leaves on. I figure that could help. I was thinking this year I may need to spray a couple times early with fungicide to make sure to get this under control. I’ll look into chlorothlonil for sure thanks for the tip. Your a wealth of info always sir.
Thanks for the bump Scott, but I don’t have much experience with fungal shot hole. All my experience is with bac. spot. I’ve noticed there isn’t much mention of fungal shot hole in the lit. except for very warm climates like CA and FL. I don’t see mention of it in the Midwest Universities, so I"m thinking our climate isn’t conducive for it, which is why I haven’t seen it (that I’ve noticed).
BTW, I’m watching the Superbowl as I type. Incredible game. I can’t believe New England came back to tie it up. Amazing. I don’t know how the game will end, but I can’t believe the Patriots were able to come from so far behind.
Back to the fungal spot, I’ve found this chart, which indicates Captan is fairly effective against it (3+).
Re: Captan burning and alkaline hydrolysis.
I’ve used Captan for years and have never seen burning on peach trees (although I’ve seen it in pictures). I’ve used Captan in all circumstances which should have burned, but not seen it yet (used it with spreader/stickers in humid slow drying conditions, even sprayed before dark with high dew/humidity and still not seen and shot hole burning from the Captan).
Captan does require acidfied spray solution if you want it effective. I acidify my tank water with citric acid. Captan breaks down very fast in alkaline water.
Me too, then I dilute it down, and put any extra on my trees. I spray my berries very early, before bloom. And yes, it didn’t work for me unless pH was down, you can use vinegar, or rainwater, or sulfuric acid. I use all three depending what i have on hand.
I use about 2 gallons of battery acid a year, so it’s usually on hand. Citric acid is another. You can get this where they sell canning supplies. If you need a lot, another source might be in order.
I have had burn with captan, as I have to use more for strawberries than fruit trees, and gave my trees three times the dose once, and it did burn the leaves really well
I make sure I dilute it now! The strawberries never burn, those things are like weeds!
For beginners some things to know is add powders last to tanks. It is supposed to mix best like this and avoid clumps that clog your sprayer. Always pour acid in water, not water in acid, so for a captan mix, water, acid, captan would be the order to use.
I would suggest using acidified water for all spraying as many products have a longer half life in acidic water, not just captan. So I do this for all sprays.
So, perhaps a dumb question, how much acidified water do you use? In other words just replace the water with equal amounts of vinegar? Or dilute the gallon of vinegar down to what mixture, i.e., a 50/50 , 60/40 water/vin or more vin/water combination?
Thank you for this info. I’ve used imidan and captan before years ago but never mixed any acid type products with it.
It depends which Captan you are using – the label is fairly clear on specifics.
Okay, good info. I will check a label out this week at the store. Thank you for the reply.
You want solution around 5.0 pH or so, so all you need is about a tablespoon or two of vinegar per gallon.I have pH test strips, and a pH meter too, so once in spring I retest my water to see how much sulfuric acid I need, I use sulfuric acid as I have golf cart batteries to maintain, and use it for my blueberry water if I run out of rainwater. I can’t give an exact amount to use, as everybody has different water. ALL water works facilities buffer water to make it basic. If they don’t you have water like Flint (what happened, they failed to make water basic, and the acid leached the lead out of the pipes).
Having said all that one or two tablespoons of vinegar is going to do it, if you have to guess.
Thanks Drew. I am on a well so I do not have the water processing worry. I just have water that has a lot of iron in it. So just adding that little bit of vinegar/acid is not an issue then. I use vinegar to clean out some areas of weeds so I usually have some gallons of it around. I will get some pH strips or a pH meter to test my water out.
I lost the link but the strips @fruitnut uses are very cool, and easier to read. Maybe he can give us the name again? I had some but ran out a year ago. Using regular litmus paper, and my cheap tester whose probe is just about gone now. I can’t remember the name or where I got them? I need more too now.
Great. Please keep me posted if you find them. Sounds like the ones to use if they are easy to read. Thank you.
A good source for those chemicals is swimming pool supplies. Always adjusting Ph there
Cool, a store is near me.
Thanks for all the replies. Lots of good info here.
Man that was a great game. Glad I didn’t turn it off when it was looking one sided. You know I think what I had was Fungal shot hole but I’m not sure how to tell them apart. The pics I saw looked more like fungal to me and when I posted pics last season of it on this forum a few people said they thought that is what I had. Thanks for the great info on captan.
Bacterial spot is much more likely. but who knows? They look a lot alike.
Another way to increase effectiveness is to use a good sticker. I will only use a pinene based product. Rain will not wash it off unless it rains for 20 hours or so. As far as I’m concerned the sticker is just as important as the fungicide you’re using, maybe even more important.