| Disease (causal agent) | Symptoms | Survival of pathogen and effect of environment | Comments on control |
|---|---|---|---|
| Anthracnose (Cryptocline [=Gloeosporium] cyclaminis) |
Distinctly zonate, pale green and circular spots. Orange to pink-colored spores on stems and leaves. | ||
| Gray mold * (Botrytis cinerea) |
Spotting of flowers. Decay of emerging flower stems and leaf petioles under leaf canopy. Fuzzy gray fungal spores form on rotted tissues. | In plant debris, especially flowers. Common saprophytic fungus. Favored by cool, wet weather. Water necessary for spore germination. | Avoid overhead watering. Remove old flowers. Improve air circulation. Control humidity to avoid moisture condensation. Treat with iprodione or fenhexamid. |
| Soft rot (Dickeya (=Erwinia) chrysanthemi) |
Plants collapse suddenly. Tuber is mushy. | Infected plants and debris. Disease is favored by high temperatures (75°F and above). Bacteria are spread by splashing water and handling. | Discard infected plants. Avoid excessive water splashing. Maintain sanitary conditions. Keep greenhouse cool. |
| Root rot (Pythium * and Phytophthora spp. *) |
Plants are stunted. Roots are discolored and rotten, lower leaves wilt and may turn yellow. | Pathogens are normal inhabitants of natural soil. Disease is favored by poor drainage and overwatering. | Heat-treat growing medium at 140°F for 30 minutes or fumigate. Drench plants with oomycete (water mold) specific fungicide. |
| Fusarium wilt * (Fusarium oxysporum f. sp. cyclaminis) |
A progressive yellowing and wilting of leaves starts with oldest. Brown discoloration of the vascular tissues in tubers. Tuber remains firm unless secondary bacteria are introduced. | Survives as resting spores (chlamydospores) in soil. No other plants are infected. Disease is favored by temperatures above 70°F. May be seedborne. | Discard infected plants and soil; don't save seed from infected plants. Good sanitation generally provides adequate control. Thiophanate-methyl drenches during early growth period should be helpful. Adjust soil pH to 6.5 to 7.0. Treat seed with a fungicide. |
| Leaf spots* (Phyllosticta cyclaminis) |
Yellowish-to-brownish spots near leaf margins. | On diseased plants and plant debris. Favored by wet conditions. Dissemination of spores is by splashing water. | Control is same as for gray mold. Protect foliage with a fungicide. |
| Septoria leaf spot (Septoria cyclaminis) |
Red concentric spots turn gray with red borders. | ||
| Stunt (Ramularia cyclamanicola) |
Conspicuous stunt. Flower peduncles shortened so that flowers open below surrounding leaves. Reddish brown necrosis in tuber. Brown irregular leaf spots. Frosty appearance on underside of lower yellowed leaves. | Infected plants and debris. Spores are airborne. Favored by warm, moist conditions. | Dispose of infected plants, keep humidity low. Keep seedlings away from older plants. Protect plants with thiophanate-methyl. |
| Cyclamen are also susceptible to black root rot (Thielaviopsis basicola) and Cylindrocladiella disease (Cylindrocladiella peruviana). | |||
| * For additional information, see section on Key Diseases. |