| Disease (causal agent) |
Symptoms |
Survival of pathogen and effect
of environment |
Comments on control |
| Gray mold
(Botrytis cinerea) |
Spotting of flowers. Decay of
emerging flower stems and leaf petioles under leaf canopy. Woolly 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. more
info * |
| Soft rot
(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 mefenoxam. More info: Pythium Root Rot, Phytophthora Root and Crown Rots * |
| 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. more info * |
| 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. |
| (Cryptocline [=Gloeosporium]
cyclaminis) |
Distinctly zonate, pale green and circular spots. Orange to pink-colored spores on stems and leaves. |
|
|
| (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. |
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