Tuesday, July 29, 2008

Greenhouse and Nursery - Fusarium on Garden Mums

Fusarium wilt is a common disease of garden mums, especially field grown mums. The following is an article on the subject.

Fusarium wilt caused by Fusarium oxysporum f.sp. chrysamthemi is a vascular disease that develops within stems. The fungus is soil-borne and after entering the plant through the roots, invades the stem plugging water conducting tissue (xylem) with mycelium and spores. Fusarium wilt symptoms are often confused with root rot but plants infected with Fusarium generally wilt in sectors (one side) and roots often appear healthy. Root rot diseases usually result in the entire plant wilting. The first symptoms of Fusarium wilt are wilting leaves on one side of the plant followed by yellowing and browning of the leaves. Infected plants are stunted and often fail to produce flowers. The entire plant may wilt and die. Severe symptoms develop during warm, constant temperatures of 80-90F, only mild symptoms may appear at 70F. Fusarium wilt can survive in soil for many years and is difficult to control once it becomes established in a field or bed.

Photo and information from the New England Greenhouse Update.

Managing Fusarium wilt centers on the use of disease-free (culture-indexed) cuttings and pathogen-free root media. Other management practices include maintaining soil pH between 6.5 and 7.0, using nitrate rather than ammonium nitrogen and drenching with fungicides. Fungicides containing thiophanate methyl (Cleary’s 3336) and fludioxonil (Medallion) have been reported to suppress Fusarium.

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