It is widely known that sulfur and Captan cannot be mixed with oil or sprayed in orchards within a couple weeks of each other on trees out of dormancy. What I don’t know is if there are any other common pesticides that are not compatible with oil. Searches for specific info on this have been futile.
I can’t think of anything else, either. But one thing I can add is for summer oils they are completely evaporated in 24 hours so you can spray sulfur the next day with no problems. I have done this a lot and had no problems. Sulfur on the other hand can stay on a long time; the usual guideline is one week but it depends how much it rains. I don’t know how long Captan stays on since I don’t use it.
I found out about the Captan/oil antagonism the hard way a couple years ago. Fried my leaves. 
I have a different anecdotal experience and have gotten some burn with trees sprayed with oil at tight cluster and Captan in the mix at petal fall. However, Captan can sometimes burn fresh green growth all by itself in wet springs, mostly just cosmetic.
Maybe I misread cause and effect. I don’t know why I assigned blame to the oil at the time, but I was already aware of the tender tissue issue. I don’t take notes and my brain seems to be gradually diminishing in its capacity as back-up.
Oil and Captan in the same tank? I did that just a couple of years ago when my mind slipped for a few moments as I was making a complicated mixture primarily to address scale in mid-summer. Decided to throw in the oil at the last moment and the captan was just a bonus to reduce summer fungus.
I realized my mistake the moment my tank was empty (thank you, brain, but a little late!). I filled my tank twice to wash off everything with water and then reapplied the proper mix. No issues beyond a lot of wasted time spraying about 50 mature apple trees on free-standing rootstocks.
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No, in my case I sprayed neem oil and a few days later the captan. Set the young trees back a bit.
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I only had a small window for spraying some Plum trees,because of rainy days.I was trying to prevent Blossom Blight and Curly Leaf Aphids.The fruit buds were just starting to show color.
I found this information about mixing Captan and Neem oil to use on Peach trees for Curculio,which the speaker says is okay,but won’t stop the insect,but for me,may work against the Aphids.
The thing is,one application probably won’t be enough and an insecticide may have to used after petal fall.
Surround is not an insecticide, but I wouldn’t mix that with oil. It would defeat its purpose, plus probably make a mess.
Why would it defeat the purpose? I think it helps the purpose and I have it done in organic and non-insecticide programs because Surround makes such a nice home for scale and mites. The oil evaporates after smothering them- I believe hort oil and Surround are entirely compatible.
Any thoughts, scottfsmith?
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Not hort oil specifically, but I thought I’d ask this here. I had a little sevin (the zeta-Cypermethrin one) left in my sprayer (about 20% of the total volume) and didn’t know what to do with it, but wanted to start spraying Neem on some seedlings when I saw aphids. I’ve refilled the sprayer with water and was going to just add the Neem then remembered this thread. Any reason I can’t use the Neem with the little bit of residue from the Sevin included?
If the label allows it you might as well get rid of it. The best thing to do is just to double spray things until the tank is empty if you’ve run out of trees that need the spray. Even just spraying it on grass can’t be too bad since a lot of the spray ends up there anyway, and it will break down quickly there- unless there are flowering weeds.
Thanks. That sounds like good advice. I just wish I had asked before refilling it, since, although diluted, I have 4 times as much to get rid of. Oh well, just means I’ll probably remember this lesson better next time.
This absolutely sucks. I should have referred to my Cornell recs. Chlorothalonil is not compatible with oil according to them and I just sprayed two orchards with the mix. If I’d searched using the word Bravo instead of Chlorothalonil this might not have happened.
Somehow I think I will escape serious consequence because buds are just starting to grow, but if I’m wrong I will post it. All the label says is to test it with any pesticides you haven’t tested before. I guess that protects them well enough.
Damn! This job shouldn’t be so hard- such a simple question and chlor is often applied at around the same time as oil. Search engines seem to be coming less and less helpful to acquire the info you are looking for and are mostly now just a tool for selling products.