Cyclamen gray-mould rot is a common problem. It is caused by a Botrytis fungus, which tends to appear when the centre of the plant is kept too moist, there is not enough air circulation and temperatures are cool. This type of rot starts at the base of stalks and quickly attacks the flower buds and leaves. All affected parts must be removed and thrown away and the plant moved to a spot with better air circulation. If the plant is severely infected it is best to discard it.
Erwinia bacteria are responsible for soft rot, which causes the tuber to rot suddenly. The plant turns yellow, the leaves quickly wilt and the tuber may turn soft. This problem often occurs when the tuber is planted too deeply, the potting mixture retains too much moisture, there is too much warmth and the plant is over-fertilized. Affected plants must be discarded.
Mites and spider mites
Cyclamen mites and spider mites may appear when the relative humidity is too low. Spider mites are tiny, but it is easy to spot their tell-tale whitish webbing. Cyclamen mites are too small to be visible to the naked eye. Symptoms include yellow, curled, deformed or discoloured leaves. It is easier to prevent these mites from appearing in the first place, by keeping the room well humidified, than to get rid of an infestation, because these insect pests are difficult to eradicate. An insecticidal soap may help, but when a plant is severely infested it is often best to simply discard it.
Other pest insects
Other insects, including thrips, which cause the foliage and flowers to become discoloured and striated, may also attack cyclamen. The best way of avoiding such problems is to avoid hot, dry conditions.
The tuber and possibly other parts of the plant contain various substances, including saponins, which are irritating and may cause serious gastro-intestinal problems and possibly even poisoning, depending on the amount ingested. Although cases of poisoning have rarely been reported, since the bitter-tasting tuber is planted in the soil, it is best to keep this plant out of the reach of children.