It is much easier to prevent pest or disease problems than to cure them, especially where African violets are concerned. Prevention begins with purchasing healthy plants and caring for them properly to increase their resistance to disease.
The most common pests of African violets are cyclamen mites, mealybugs and thrips. Because it is very tricky to cure a cyclamen mite problem, it is often easier to simply throw out the infested plant. Mealybugs (scales) are also difficult to destroy, as they tend to lodge in the crotches on the crown. Take a cutting, using a healthy leaf, and throw out the mother plant. The same treatment is also appropriate for thrips infestations. You may also wish to try insecticidal soap.
Springtails will sometimes appear in the soil if it is kept too damp or contains too much organic matter. It is often enough to let the soil dry out and then water less frequently.
The fungal diseases that affect African violets are generally a result of poor growing conditions.
Root, stem and crown rot, caused by Phytophtora sp. and Pythium sp. may set in if the soil is kept constantly damp. It is best to throw out any infected plants.
If humidity levels are too high, Botrytis Blight (Botrytis cinerea) or grey mould may appear on the flowers, young leaves and any dead leaves that have not been removed. The best way of preventing the problem is to use scrupulously clean pots and saucers and to groom and inspect plants regularly.