Fusarium Wilt in Chrysanthemums

Protect chrysanthemum flowers from fusarium wilt by treating the plant when disease symptoms are noticed.

Chrysanthemums are desirable decorative plants due in part to their ability to attain showy, colorful blooms well into colder weather periods. If you wish to take advantage of the aesthetic advantages that this plant can offer, an important component of bringing the plant to bloom is to protect it for fungal diseases such as fusarium wilt that can threaten the long-term health and life of the plant.

Fusarium Wilt

Fusarium wilt is an extremely pervasive plant disease caused by the fungus Fusarium oxysporum and is problematic to a wide range of plant species. The fungus lives in soil and can persist there for years, even in the absence of a plant growing in the soil. High soil temperatures of 80 degrees Fahrenheit and hotter favor the fungus, and the fungus can often be carried into soil on plant cuttings used for propagation.

Symptoms

Early symptoms of fusarium wilt depend somewhat on the plant being attacked, but it will typically involve yellowing and wilting of plant foliage; seriously infected leaves may defoliate to the ground. Cutting open the leaf stem of a chrysanthemum will show a red or tan discoloration. As the infection progresses, the fungus will sporulate and white tufts of spores will show on the outside of plant stems.

Natural Treatments

Natural treatments begin with preventative steps. Chrysanthemum seeds purchased for planting should be treated with a preventative fungicide or heat treatment since the disease is often spread by spores on the coats of seeds taken from infected plants. Never use cuttings from a diseased plant to propagate new chrysanthemums. Adding lime to soil and using nitrate fertilizers also helps minimize a chrysanthemum's susceptibility to the disease.

Chemical Treatments

Fungicides are generally not recommended for control of fusarium wilt chrysanthemums. Indeed, you are likely to find approved fungicides approved for fusarium wilt on chrysanthemum and other plants, but the benefits of using these treatments are typically far outweighed by the drawbacks. Instead, adjust cultural practices to allow the chrysanthemum to grow back healthily. If necessary, replant the chrysanthemum in a different part of the garden that is free of the fusarium pathogen or start new chrysanthemums using more disease-resistant cultivars.

References

• Purdue University Cooperative Extension Service: Fusarium Wilt and Stem Rot of Chrysanthemum; Tom Creswell; Aug. 31, 2009
• University of California Agriculture and Natural Resources Statewide IPM Program: Floriculture and Ornamental Nurseries -- Fusarium Wilt
• University of California Agriculture and Natural Resources Statewide IPM Program: Floriculture and Ornamental Nurseries Chrysanthemum (Chrysanthemum grandiflora)