Above Crown rot, ( the work of the fungi Phytophthora) I knew about it but never experienced it in my many years of growing African violets. Well I was not only introduced to it first hand in December and January but it moved into my growing room and took up residence. I have now lost 1/3 of my plants. I believe now it has been banished from my plant room if not my house thanks to a number of practices I have changed and 10% bleach. It was my fault. I have always used a rather heavy potting mix as I try to minimize the time I spend watering plants. And with this very early and very cold winter we are experiencing in Ohio (Temperature as of this writing is -5 degrees below zero or -20.5 degrees Celsius) I am seeing extremely low indoor relative humidity levels. The plants dry out then I over water. I had not been inspecting the plants on a regular basis as I have been busy with other projects. Root rot, crown rot is caused by the Phytophthora fungus, which attacks the roots and, most notably, the crown of African Violets. Usually the first sign and symptom which I missed as I was not paying attention is the drooping of the leaves despite the fact the soil was moist, if not wet. That was indicative of the fact that the roots have failed and are not absorbing the moisture. At lease at this point the crowns are salvageable which I did a fair share of crown removal, bleaching and rooting including a 10 yr old Granger Red and White stripe. Most all the plants I removed the crowns and treated with 10% bleach and placed in fesh potting mixture or mixture that was baked at 380 degrees for 45 minutes. They are all doing very well.
Hear is a nice example of a very advanced case of crown rot.
Other Symptoms include but not limited to when the crown has a web like substance on and around it. Leaves become darkened and or wilt while green. Growth is slowed or totally inhibited.
I did an extensive web search on treatments and the findings were rather dismal. Nothing can really be done other then discard the plant and soil and pot. On plants where the crown was still in tact I removed it making sure the cut was above the infected area. I then placed the crown in a solution of 10% bleach (I prefer Clorox). It was sealed in a container and essentially inverted for 10 minutes. It was rinsed well and potted in soil that was baked at 380 degrees F for 45 minutes. And the pots I used were also placed in 10% bleach for 30 minutes and rinsed well. The crowns in their new soil (moist but not wet and much lighter) were placed in plastic bags. In 2 weeks most of the crowns has a nice little root system and were removed from the bags.
Prevention is always your best bet for successfully controlling Crown Rot I guess. But since I never had the issue I just assumed I was fine and it was not something I was concerned about. So going forward I will not overwater, I not let the soil dry out completely before watering. Finally I started using a more light, porous potting soil. I am also (for the first time) starting to consider some sort of self watering device.
I cannot end this post with the painful pictures of the carnage of a fungus. The below image comes again courtesy of J. Miemietz, a grower of African violets and an exceptional photographer who resides in Germany. This is her Mauna Loa that was grown from a crown. Good to know as bleak as things are or were on my plant stands in Ohio, things are green and in bloom in Germany.