Copper Sulphate (CuSO4) Solution as a Fungicide ?
 

Hello everyone.

I have several hybrid Phal seedlings with sphagnum moss medium. With the day progresses more and more into August, here (in Indonesia) the rain becomes more and more often. The implication is my seedling medium become moist longer than before. Now I only water it about once every week, while a few weeks ago I watered it twice a week. So, as a prevention, I think that I need to spray my seedling with some fungicide.

I have some copper sulfate pentahydrates crystals (CuSO4.5H2O) from many years back still in good condition. And I read somewhere on the internet that copper sulfate solution can be used as a fungicide on crops.

My Question is: Is it true? Can I use copper sulfate solution as a fungicide on orchid? Is there any side effect? What dose should I use?

Any answers are welcome. Thank you.

Yes, copper sulfate can be used as a systemic and topical fungicide and bactericide, but there are some dendrobiums and thin-leaved orchids that find it to be toxic. (It damaged a coelogyne of mine once.)

For what it's worth, Phyton 27 is a copper sulfate product, with the equivalent of 200g CuSO4-5H2O per liter of water, and that is used by further diluting it to a 0.5%-2% solution.

Back to your original query - water, by itself, is not an issue, and I have found that plants in potting media that are very water-retentive do OK as long as it stays warm and rains a lot. Over the last two months, we have averaged over 1" a day of rain, and my phalaenopsis in sphagnum are doing great.

That, of course, has no bearing upon your outcome, but I think I'd look at changing the potting medium or protecting the plants from the rain before I'd resort to preventive fungicide use.

Thanks, Ray.

If there's no any side effect of copper sulfate solution on phal (proper dose, of course), I'll try that this weekend.

The media are still newly potted (since May 18), so I don't think I'll repot it for a while.
The current conditions are sphagnum moss + fine osmunda fiber media on plastic compot (about 15 cm dia.), with 10 seedlings per compot, and all the compot protected from the sun and rain by means of a small hut with a semi-translucent white plastic sheet roof. With these conditions, I have a gorgeous growth rate on all seedlings.

What do you mean? There are no side effects.
If you take antibiotics without need, do you think it's okay?

I don't know. Maybe like Ray said about the unwanted effect on Dendrobium, Coelogyne, and some thin leaved orchids.

Like "Nexie", I avoid preventive treatments of anything.

Basically, you are hoping to compensate for a shortfall in cultural parameters by the application of what is an environmental pollutant.

I think in my climate area it is necessary to apply preventive treatment for fungi related deceases during monsoon especially from October until February, at least once a month. Even though I have small hut protecting my orchids, it is an open hut, not a closed one like a green house. So when the environment is quite humid so are the media.

Thanks for the advice

Hi Ray!

I did some math on the Phyton 27. After all this math I saw your message. However, my results differ from yours. My findings are 258.8 g / L copper sulfate in the stock solution. In the end, use about 1-3 ml of the stock solution to get the final solution of 1 Liter. But this amounts to a dilution of 0.1 - 0.3%. I now doubt my own math skills. Can you clarify this? I don't want to accidentally overdose my orchids.

Thanks!

Let me work this out right here:

According to the label, Phyton 27 contains 21.36 (I formerly used 20%) weight percent copper sulphate pentahydrate, yielding 5.5% elemental copper. They recommend 1-2 teaspoons/gallon, which is 0.13% to 0.26% dilution. You're right - I was off on my dilution levels!

Great! Thank you for checking the numbers.