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Anthracnose is the most important disease of sycamores and is common throughout Indiana and where sycamores are grown. This fungal disease is favored by cool, wet spring weather.
Symptoms: The most characteristic symptom appears as large irregular tan to brown lesions that develop along leaf veins, sometimes expanding to the leaf margin causing distortion of the leaf. Twig dieback and wilting and browning of newly emerging leaves frequently occur. Numerous cankers (localized, injured areas) occur on twigs and branches. Severely infected trees are defoliated and may appear more dead than alive.
Disease Cycle: The fungus, Apiognomonia veneta (anamorph: Discula platani), overwinters in infected leaves and branch and twig cankers. In spring, spores are produced and spread by wind and splashing rain to newly emerging leaves, buds, shoots, and twigs when conditions are favorable. Spores are produced from recently infected tissue, allowing secondary infections to occur.
Management: Even during years of severe infection, sycamore anthracnose does not result in tree death. Therefore, the most practical control is to water and fertilize stricken trees to help them recover from severe defoliation. Spraying is generally not warranted on large, or older established trees.
For more information, refer to BP-9, Anthracnose of Shade Trees (PDF 496K).
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Last updated: 12 June 2002/tlm.
The Plant & Pest Diagnostic Laboratory at Purdue University.