African violet leaves slowly brown and rot
I have been raising 3 African violets I rescued from the garbage heap at Lowe’s 3 years ago. They cost me $1 for the lot of them. I didn’t even want them as they looked so bad, but my girlfriend convinced me to give them a chance. I was skeptical that they would survive, but I managed to nurse them back to health and they have been thriving.
The largest one is now 15 inches across and the next largest is 10 inches across. The smallest has lagged and is only about 6 inches across but it is the one that blooms the most. I bought them about 2 inches across in a thimble of a pot and about 1.5 years ago transplanted them to larger 4-inch pots.
I water about once per week, sometimes less if the soil isn’t super dry yet. I add a weak liquid violet fertilizer about every 3rd time.
Two weeks ago I was surprised to see the smallest violet had droopy leaves that were brown at the edges. These were the oldest, biggest leaves on the plant. I sometimes remove old leaves as they age out so I removed a couple and checked back. A few days later they had gotten more brown and rotten looking and the green stems had started to turn to jelly. Fearing disease I cut off any leaves that looked even partially brown and stopped watering.
Tonight I checked and even more leaves were falling victim and more stems were rotted. The stems remained green but were like jelly. I pulled the plant out of the pot and it hardly has any roots. I was expecting/fearing black rotted roots but was surprised to find almost none. There was just the taproot which still looked healthy enough and there are still a handful of healthy looking leaves.
I cut away anything remotely gelatinous, dumped the soil, and repotted with the crown just touching the surface. Was that the right thing to do? Should I use some sort of anti-fungal or antibacterial?
I am at a loss for why this one plant is afflicted. The others receive the same care and look fine - at least for now - although obviously their growth rates have differed so maybe this one has always been weaker. Should I repot the others, too, to inspect their roots and prevent the same fate?
I am so proud of my rescue violets! Advice is appreciated.