Last year I wrote a number of posts about african violets. I got some leaves from eBay and I was propagating some of the plants that I had. In the early summer, all was well.
But by the end of the summer, all of the plants had died. On larger plants, the petioles (the stalk that attached the leaf to the crown of the plant) of the leaves had turned mushy and the crown of the plant looked strange – it was as if the small leaves weren’t expanding. Instead they were growing in tight little clusters. Smaller plants lost their outer leaves and weren’t growing well.
I went to the Optimara site and used their plant doctor tab to try to diagnose this problem. After looking at a lot of different options, I came to the conclusion that my violets had fallen prey to the fungus pythium.
Pythium is a fungus that can occur in potting soil. Spores of the fungus stay dormant in the soil until the conditions are right and then they can infect a plant. While most reputable produces of potting mix sterilize their soil, last year I purchased a bag of potting soil from a local garden center that was their own mix. It looked like a good potting mix but all of the violets that I planted in it ended up getting a pythium. It must have been filled with pythium spores.
What I’ve learned from this is that it’s best to sterilize potting mix if you have any questions about it. To sterilize a potting mix, it needs to be heated to 180 degrees for 30 minutes. This can easily be done in an oven by putting the soil in a pouch of foil and using a meat thermometer to monitor the temperature of the mix. If I had sterilized the mix from the garden center I probably wouldn’t be writing this article!
But I also realized that I had something to do with this pythium outbreak. African violets needs a constantly moist growing medium. Letting them dry out can open them up to pythium due to the stress that it causes in the plant. I’ll be the first to admit that in the summer, my houseplants face the ultimate Darwinian experiment – it’s survival of the fittest. Watering and plant care fall by the wayside in the summer. During those months the violets dried out and then were watered and this back and forth between dry and wet helped the fungus to find a home in the violets’ tissue. While the unsterilized soil provided the pythium spores, my care – or lack there of – gave the fungus a perfect opportunity to grow.
When a violet gets pythium, there’s nothing to do but discard the plant. Fortunately none of the plants I had were very valuable.
All of this has been a great learning experience. From now on I’ll be much more selective in the potting mix that I use with violets and I’ll be sure to sterilize the mix and the pots before repotting or propagating. I’m also playing around with some different techniques for making self-watering pots which would keep violets from drying out. In addition, when I see a plant with petioles that are soft or mushy, I’ll be much more aggressive in culling the plant to prevent any spreading of the fungus.
I am a little sad that the eBay violets bit the dust – I was excited to see what the unique varieties would look like in bloom. Now that I know about pythium I may try growing some again. But for now I’ll just be content with the lesson that I learned and the new fungus that I discovered – pythium.