Copper fungicide

[Mitty]

Do the blue spots on leaves left by spraying with Copper fungicide stay or will they wash away after a time.

 

[Wires_Guy_wires]

Depends on the product. If you've used copper sulfate, there shouldn't be blue spots. If there's blue residue from copper sulfate, you're using waaaay to much.

It could kill a plant in those amounts and it should be rinsed off.

For commercial products, I wouldn't know. But any high salt concentration on leaves is kind of bad.

 

[Mitty]

Hi there ! Copper sulphate is exactly what I thought. I am using BONIDE ,ready mixed. I have also purchased another product which comes as a dissolvable powder. I use it at 1/3 strength. No way near the quoted use of 1 packet to 5 litres . About 1/4 for 3 litres. . I am not able to rinse the blue marks off, they are stuck well and truly. Should I risk ever using Bonide again. The instructions must be incorrect. I was also told to use it when the sun was high to reduce evaporation times.. I imagine soaking the trees as suggested is fatal to my trees. . Any other suggestions would be greatly received. If I do nothing my Bonsai apples are destroyed as last year, by the cedar-rust. My trees turn completely " Rusty " and die.

 

[ysrgrathe]

Yeah I have never noticed residue with copper. I usually use an aqueous concentrate.

You can get residue with daconil or lime sulfur at high concentrations.

 

[Adair M]

I get my copper wire turning blue after spraying with the Bonide copper spray. The trees, pines, don’t seem to care.

 

[Mitty]

Thanks all. I have double checked and the actual make is BATLLE Copper fungicide. It comes in a sachet which will make up to 5 litres. I took 1/4 of the powder and made up 2 litres. On a second look it seems to look pale blue . It does partly dissolve off the leaves with a spray but only if I rub the leaves.. It is strange as I went out of my way to weaken the suggested dose.. I had been using BONIDE ready to spray , it still left blue/white marks. So I thought by buying a powder , I could weaken the mixture. It is a copper salt, but not actual copper sulphate itself. As Copper Sulphate contains the 2 useful elements , I would have thought a very dilute solution should in theory be usable. However no doubt even this is just not on !! Do the English make another more usable product ??? for Cedar-apple rust..

 

[Leo in N E Illinois]

The blue stains will most likely wash off, wear off, or slough off in a few weeks. I would not worry about it.


By not following directions, using a weaker dilution you potentially have used less than an effective dose, in which case the results will be developing a resistant strain of the fungus rather than killing the fungus. Read and follow label directions. No more, no less.

If you do read the label, it will tell you if it was copper sulfate or a copper quaternary ammoniacal compound as the active ingredient. I use Cosan 27 on this side of the Atlantic, it is the later of the two copper compounds. I don't find it very effective.

 

[ysrgrathe]

Look into Sygenta Score 250 SC (triazole fungicide, Difenoconazole). It is listed for rust.

 

[Mitty]

Many thanks , Leo. Very interesting. I take your point about dilution.. I am worried about using Copper fungicides as I lost about 6 trees last year by using BONIDE full strength. This a copper based fungicide too. Well, LEO , I will let you all know ………………….I wish I could treat the Cedar, but it is in a graveyard. It was planted in the 1800s.
Many thanks for all your help. Regards Mit

 

[KiwiPlantGuy]

Many thanks , Leo. Very interesting. I take your point about dilution.. I am worried about using Copper fungicides as I lost about 6 trees last year by using BONIDE full strength. This a copper based fungicide too. Well, LEO , I will let you all know ………………….I wish I could treat the Cedar, but it is in a graveyard. It was planted in the 1800s.
Many thanks for all your help. Regards Mit

Hi Mit,
I agree with @ysrgrathe that Score or Alto will work to control an outbreak. (sorry can’t remember active ingredient for Alto). Both of these are “curative” and systemic fungicides. Eg- kills the fungus as the fungicide attacks the spores.
When you are just using a Copper based chemical, you are only using a “Protectant” fungicide, that works to protect the leaves BEFORE an outbreak. Or in other words, once you have an outbreak, spraying the clean leaves will work, but won’t work with infected leaves.
Therefore you need a curative fungicide and mix the two together (eg - Copper and Score). Though I doubt that the systemic chemicals would be available to the gardening community.
Hope that explains something.
Charles

Oh by the way, using Copper Sulphate as fungicide is weird. Because this is a trace element fertiliser. Copper Oxychloride is your active ingredient for the fungicide.
Using Copper Sulphate in a strength ( more than a few grams) will in no doubt BURN real bad.

 

[Mitty]

Thank you KiwiPlantGuy . I really have been led up the path here.. Some of the claims made by various makers are quite stupid , not helping the growers, only their pockets.