Dormant Spray and Copper Spray


…and there is reason to combine oil with copper, as it helps the residual activity of copper. I am waiting for temps and precipitation to cooperate too.


I would rather make two separate applications, that way I can control each ratio of copper to water, and dormant to water.


Yikes— looks like I’ll be waiting a long long while… it’s only been above 40 for 3 days in February. 20 or lower since…


Early spring, before leaf buds begin to swell- or it’s too late. Maybe that’s the reason for your failure.


What? That would make late winter or early spring app almost impossible. It is hard enough to get oil down 3 weeks later and the label is to avoid freezing temps with 24 hours of spray with hort oil- but only on trees with green showing. I don’t worry about freeze when spraying copper on dormant trees with nothing but a little flower bud swell.


What do you mean 3 weeks later? I was told to let about 3-4 days pass if doing oil n copper separately with no rain forecasted 24 hrs after each app



I did remember reading this and looked and found that the Bonide bottle says: " Do not apply when temperature is greater than 90f or less than 40f"

HOWEVER, your comment peaked my interest and I looked further and could NOT find others mentioning this lower imitation but I did find in

General Comments about the Use of Horticultural Oil by Mark Halcomb, UT Extension Area Nursery Specialist
and Dr. Frank Hale, UT Extension Professor of Entomology, Nashville, Tenn. - (Revised 4-11-2012)

"Labels continue to include this advice DESPITE INCREASING EVIDENCE THAT THIS TEMPERATURE RANGE IS CONSERVATIVELY ( natch for me ) NARROW ( my emphasis added) It’s more important that the plant is not stressed for moisture and the humidity should be low enough (45 to 65 percent) for oil to evaporate quickly".

So, @Alan,… I will admit to being partially, slightly, somewhat, potentially arguably, but surprisingly, in error :blush:



I thought you were talking about copper! I’d never heard that of oil either- always freezing temps to be avoided. In one orchard I manage, a tree care co. put down oil when it was about 26 degrees and apples were at half inch green and covered with frozen dew. I lost entire 60 year old scaffolds on some trees. I’ve accidentally put it down on similar trees when it turned out to be freezing- or at least the frozen dew I noticed too late made me think it was. I filled the tank with straight water and attempted to wash it off. No injury- for whatever reason. I also once injured tender pear trees with oil when I sprayed during a mist years back.


Yes. If the Northeast warm spell in February started peach bud swell it may be too late to stop peach leaf curl with spray copper according to Penn State Extension. Best to spray now if no rain is forecast for a day or two and hope for the best. In 2016 leaf curl was bad for me. In 2017 I had no problems with it since I sprayed in late fall and early spring before bud swell.


I read that [about the temp] on the label of my dormant oil, too. Fortunately, there was one warmer day last week, and I took advantage


Thanks Alan -
Once again, I forgot to spray in the fall and I haven’t sprayed yet but I will this weekend. I hope I didn’t blow it for another year!!

For some reason, when I mix copper and oil, my sprayer gets clogged. If I was going to do separate applications, should the copper go on first, and then get covered with the oil?


Hey Bart- copper first then oil! Make sure it’s 40° and somewhat cloudy day without any rain in forecast for 24 hrs for best application… I also wait a couple days between copper then oil


I believe that you only have to worry about freezing temps with green tissue. Horticultural oil replaced the much heavier stuff so that leaves could be safely sprayed. I’m going to spray copper and oil tomorrow or Mon. I don’t care if it is 24 degrees the next night.


Let me know how it works out Alan. I hope it doesn’t damage your trees


Don’t worry, back when I started managing fruit trees there was no hort-oil light and oil had to be sprayed on dormant trees only. Temps were often freezing on nights of application.


I like to spray oil in the fall. I mix it with lime sulfur as that makes the oil more deadly to insect eggs and fungal spores. Only once a season. I don’t have high small bug pressure here either. Mites and aphids eggs will be killed. In late winter I use copper with Nu film 17.
I like the way the copper covers everything with the Nu film., Which will keep it there 2 weeks to 2 months, yes that long, or even longer. Never any leaf curl here.


I did copper about 4 weeks ago with the Bonide All Seasons. I did it again with a far less copper mix and it seems …at least so far… everything has been well protected. It took care of a mossy fungus on my Anna Apple and it appears all my other trees are fine. I am thinking I will do the All Seasons a few more times in the next month for good measure…


By the way, I double checked with an adviser that works with my ag chem supply company today and he assured me that there will be no danger in spraying oil before hard freezes when trees are dormant. I admit that on-line info- even from universities, suggests there is danger, but I think they are just erring on the side of caution and being careless in the process. I trust this guidance because he works for a corporation that can’t afford to give commercial growers wrong info.


I think freezing in now over in Zone 7, but my early peach is showing swelled buds wit a little pink and green. Is it still safe to spray copper / oil?


You should be ok to spray. Do it on a cloudy day though without rain in forecast. Early morning is best