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Horticulture and Home Pest News
Horticulture & Home Pest News is filled with articles on current horticulture, plant care, pest management, and common household pests written by Iowa State University Extension specialists in the Departments of Entomology, Horticulture and Plant Pathology.

Sooty Mold

This article was published originally on 5/3/2002

Sooty mold fungi cause needles, branches, or leaves of trees or shrubs to appear black. The common name "sooty mold" is descriptive of the black coating or crust that is formed on these plant surfaces.

Several different species of fungi often exist together to cause the sooty appearance. These fungi don't infect plants, but grow on the sugary honeydew excreted by aphids, scales, mealybugs, and other insects.

The growth of these fungi is primarily an aesthetic problem, although they can be detrimental to plant health by blocking sunlight and interfering with photosynthesis.

Control of sooty mold is targeted at preventing or reducing insect populations. Scales and aphids are usually the culprits in sooty mold infestations. It's important to identify the species of insect present to determine what control measures to apply and when.

In Iowa, sooty mold is most commonly spotted on pine, maple, and elm trees. A pine sample showing sooty mold was recently submitted to the Plant Disease Clinic. Pictures can be found at the Plant Disease Clinic website . (Click on "Plant Diseases" and then "Nonpathogenic Fungi".)



This article originally appeared in the May 3, 2002 issue, p. 53.

Year of Publication: 
2002
Issue: 
IC-487(9) -- May 3, 2002