Best time to spray copper?

When is the best time to spray copper for:


There are so many different explanations I am a little unsure. I think the right answer for spring is right before the buds turn green/start sprouting leaves. Is this correct? If the buds are green do you harm them by spraying copper? If you do it earlier what do you lose? This is my first year spraying (other than for Japanese Beetles) so I am not confident in what I am doing.

I am interested in this question as well as I just planted a peach. But I am going to wait until after the holiday to call my county agriculture extension to see what they say.

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Our county AG Extension is not so hot when it comes to fruit …

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Also another question, is better to spray copper after you prune or before? If the copper does not hurt the fresh cuts I assume after.

I spray copper ( I use copper hydroxide) before or at bud break. You should prune your trees before spraying. Otherwise, it is wasteful to spray then remove limbs. It won’t hurt the exposed wood/cutting area.

Have you check out @scottfsmith’s Low Impact Spray thread. He suggests spraying stone fruit at pink, apples at tight cluster and pears at swollen. It probably the ideal stage but I am too lazy and try to spray all at once :smile:

Spraying copper after trees leaf out could cause phototoxicity especially spraying at full strength. You need to check the label.

I add sticker to it. Wait for a rain free day to spray.


Hi, I agree with Mamuang as to mixture. My schedule however, is three holidays. Thanksgiving, Valentines Day (after I prune in Feb.) and Easter. So easy to remember. Copper and a sticker! Works so well!


I’ve heard something similar, but in our area it is Thanksgiving, New year’s and Valentine’s day. Last few years, Valentine’s day was too late since spring sprung on us in January. This year, it looks to be on time!

I’m not expert. But the coper compound easiest to get around here is coper sulfate. I haven’t seen anything be hurt by it even when spraying during the growing season as long as you follow directions on label. For pears, the rule here seems to be to spray when dormant and then spray again while the pears are blooming. It doesn’t seem to hurt the flowers, and bees transmit fire blight to flowers, so to have any positive effect on that problem, you need to spray flowers with at least a mild solution.

A note about using holidays for spray times. Valentine day can be well into spring here in SE Georgia but is deep dark winter in Alberta where I used to live. God bless.


What is the difference between copper sulfate and other copper?

I read somewhere that copper can damage the soil and it kills worms. Is this true?

Our deciduous trees hadn’t gone dormant by thanksgiving. If that’s the case do you spray anyways, wait or manually remove the leaves? It was closer the New Years before they lost leaves on their own.

Important differences are how soluble the copper is and how much “metallic” copper is contained in the product. Coppers in the form of hydroxide rather then sulfates are normally less soluble and safer. The safest is in the form of a copper salt like Cueva, but the product also contains the least amount of copper. The amount of copper is described by the Metallic Copper Equilivent (MEC). Some commercial spray guides refer to the proper amount of MEC per acre to make things a little easier.

I will check and see what I kind of copper I bought from Home Depot, I am traveling now so I cannot check. Thanks!

That’s interesting,because we just had a major water drain blockage where I live,so I did some searching online to find ways to fix it.
The problem was most likely tree roots had entered the line.One of the most commonly used chemicals to kill the roots is Copper Sulfate poured into the drain.This is suppose to only kill them within a few feet of contact and not harm the whole tree.
Ultimately,a plumber was called and a drain snake was probably used. Brady

I worked as a tree/shrub/turf guy during one period of my life and since our routes were so large it wasn’t possible to be spot on timely, however saying that, here’s what we tried to keep up with whether spraying copper or sulfur:

Bud movement and/or slight appearance of leaves ( plus horticultural oil at this time )
flowers still on the tree but falling off
formation of fruit occurring

and any necessary follow up sprays according to individual needs.

Fall: dormant spray: copper or sulfur + oil.

Of course we sprayed every square inch of the tree and we also (don’t know if it’s practiced in horticulture) soaked the ground pretty good at the dripline.

I was in my truck and spraying at 5 am and once the weather hit 70F I stopped spraying the fungicides and oils. For the homeowner spraying at morning or after sundown when temps are 70F or below is the time to do your spraying.


So i sprayed my Peach and Apple trees today. It was upper 60’s and windy (not good) but i had to do it as I travel a lot and might not be able to spray later. Crazy weather, if it keeps up i will lose my peaches again to frost. One thing I noticed after reading the copper concentrate label was that there were no guidance for plum trees. Is copper any good for plum trees? I only have one …

What do you use for the sticker?

Hi-Yield surfactant should be at about every home improvement store, garden center, or you could get it online.

Horticultural oils mixed with copper/sulfur also act as surfactants. Just make sure your trees are fully dormant when spraying these mixtures and don’t spray horticultural oil on trees that are flowering. Shake your tank sprayer often while applying.

Do read the label about proper mixing ratios of dormant oils and neem oil. And don’t spray hort oils if temps are to go near freezing.

And yes, copper is good on plums.


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I’ll be spraying copper this weekend. :kissing_heart:


MrsG: Were in the same zone and I spray my Copper combined with Oil in
two applications a couple of weeks apart usually starting mid to late March.
Do you do the same or make separate applications? Do you apply Copper
in late fall as well?

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