Copper and your orchids

[Undergrounder]

OK so fungi hate copper, to the point that you can get copper sprays that control leaf mould problems..

People also reccommend you soak bark in copper sulfate to treat them (as well as lime, nitrogen fertiliser) for use as an orchid medium.

On the other hand, i've heard that people use copper sulfate to pour into their drains to KILL roots! (eep!)

So i was wondering if anyone uses copper, and if its possible to find a level where it controls rot as a part of your watering regime, but doesnt hurt the plants..

[BikerDoc5968]

I use a fertilizer that contains Cu = 0.05% chelated CuSO4 as part of minor supplemental elements. So alittle can't be bad.

[camille1585]

In France, we have a well known organic fungicide called 'bouillie bordelaise' It's a mix of copper sulfate and lime. It works best in prevention of fungi related problems, and can cure infected plants to a certain degree. The only drawback is that it turns eveything blue, unless you get the colorless kind! Just as a word of warning, it should not be used at temps over 24-25°C (75°F) as it becomes toxic to the plant, causing burns.

I would not use it at every watering, because if the medium behaves in any way like soil, the copper will build up in the medium and high doses kill plants. Also, I know that in the case of vineyards, they don't spray while the vines bloom as it causes the flowers to abort.

Personnaly, for all the above reasons, i woul not use it on my orchids, unless I really needed it.

[orchids3]

We are a little worried about fungus and bacteria here in Florida as the huricanes in the area can keep us wet and overcast a lot. Investigating Cu based mixes to protect my plants a chemist friend and orchid grower was contacted. Cu based compounds are good except when media is acidic. Acidic mixes can turn Copper mixes into strong phytotoxin or what is better know as a herbacide. I elected not to use it on my orchids. Some people do use it with success - some kill their orchids. it depends on the condition of the potting mix.

[Undergrounder]

ah thankyou everyone, such great posts... orchids3 that is very interesting and i guess is why camille's bordeux mix has lime in it! im trialling a method of growing Phal seedlings that uses 100% humidity to minimise watering and have been thinking about cheap methods to systemically combat the increased mould risk that might occur, so if i do add copper to the mix that's very good information to know, thankyou.

[quiltingwacko]

I am trying colloidal silver in one of my gravel trays to see if it will help with algae.

[Ray]

Copper is a great fungicide, but also a great herbicide - especially in thin-leaved plants.

That's why I recommend Physan or even a cinnamon extract over it.

[Undergrounder]

you mention thin leaved plants, have you heard of its use as a minor adjustment to the watering regime, ie: only on the roots? I was imagining adding a slightly larger amount that is usual on fertilisers as a type of systemic, ie: the copper build up is taken up by the roots and adds to the plant's general resistence, as well as having a mild antifungal effect on the surface of the roots themselves.

P.S. I realise it's probably a matter of 'try it and see', and a few posts have good reasons for not doing it, or at least keeping a slightly basic pH in the fertiliser to stop it being herbicidal.. but it sounds like a powerful fungacide, so it might be worth it as a small experiment on my part.

[cirillonb]

I am probably beginning to sound like a broken record but it continues to baffle me why, with all the tried and true commercial and home-remedy products available to handle all the woes of orchid growing someone would want to try an unproved and possibly dangerous (to orchids and self) remedy. I notice that several broad spectrum antifungal/anti-pest products contain a tiny bit of copper. I presume they know what they are doing. I suspect the French product may be used on bigger and hardier plants like grape vines where a little persistence of antifungal is a good thing and where rains will dilute then remove the copper which is not good for people either.
Nick

[camille1585]

Originally Posted by cirillonb

I am probably beginning to sound like a broken record but it continues to baffle me why, with all the tried and true commercial and home-remedy products available to handle all the woes of orchid growing someone would want to try an unproved and possibly dangerous (to orchids and self) remedy. I notice that several broad spectrum antifungal/anti-pest products contain a tiny bit of copper. I presume they know what they are doing. I suspect the French product may be used on bigger and hardier plants like grape vines where a little persistence of antifungal is a good thing and where rains will dilute then remove the copper which is not good for people either.
Nick

The french stuff is used almost exclusively on outdoor plants, mainly vinyards, orchards, tomatoes, potatoes. I have never heard of it being used on indoor pot plants, so trying it on orchids might be really risky.

And I agree, there are many good chemical fongicides out there that probably do a much better job with lower risks compared to copper based stuff. In France, 2 often used active ingredients are Dithane and mancozebe. Those have always worked for me!