African Violets and Soil Fungus

I seem to have an issue with african violets and various kinds of fungi. In the past I’ve written about pythium and how it decimated my plants.

Now I seem to have some new fungus, or better said, fungi. In the spring I got some leaves of plants from Lyndon Lyon Greenhouses in New York. The leaves came quickly and were in very good shape when they arrived. I took the time to “sterilize” the potting mix that I was using and assumed that all would be well.

A few weeks after potting up the leaves I noticed that there was a brown fungus growing on the top of the soil. When the pots dried out and I watered them, a puff of brown powder would emerge from the top of the soil when the water touched it – that was the fungi spreading its spore into the environment!

I kept the pots of leaves separated from other plants but I noticed that a schefflera that I’d potted with the same potting mix had identical brown fungus growing on the surface of the pot. It’s obvious that there was some kind of fungus spores in the bag of potting mix that I used and my attempt at sterilizing the soil didn’t accomplish its purpose.

Fungi on Potting Mix

Fungi on Potting Mix

I was tempted to throw out the african violet leaves but I decided to wait and see what would happen. As it turns out, this brown fungus didn’t seem to affect the plants. Small plantlets started to grow but at the same time that the plantlets were growing, a white fungus started to grow on the surface of one of the pots. I’m not a mycologist so I don’t know what kinds of fungi these are but I know I don’t want them spreading to the rest of my plants.

After some searching I found a copper fungicide that’s said to safe for african violets. Its active ingredient is copper octanoate, a kind of copper soap. The way copper works as a fungicide is to denature proteins and thus disrupt the growth of fungi. It can have a pytotoxic effect on plants as well if the concentration of copper is too high. The solution I’m using is only 0.08% copper octanoate so I’m not too concerned that it’ll harm the violets. If they do seem affected, I’ll flush the plants and soil with water and hope for the best.

I sprayed the surface of the soil and will repeat this in about a week. I’ll continue to keep an eye on the soil and when it comes time to pot the plantlets, I’ll remove most of the soil from their roots and dip the entire plant in fungicide. This should stop the fungi and keep it from becoming a permanent part of my indoor garden.

I’ve heard of people getting bad bags of potting soil and ending up with a fungus gnat infestation. I’m glad I didn’t get any gnats in that bag of soil; I just got the fungus! Here’s hoping the copper octanoate is the answer to my problem.


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