Sycamore Anthracnose Fact Sheet No. 2.930 Gardening Series|Diseases by C.E. Swift* Anthracnose is the common name given Weather Influences Quick Facts to a group of fungal pathogens which cause Weather determines the severity of • The most serious disease dark, usually sunken lesions. The term anthracnose. Frequent rains and cool of sycamore trees is anthracnose is from the Greek word for temperatures promote the disease. If the coal or charcoal. These are typically diseases average temperature during the two-week anthracnose. of leaves, stems or fruits. The sycamore period following emergence of the first leaves anthracnose fungal organism attacks • Anthracnose often is is below 55 degrees F, the shoot-blight phase confused with frost damage. sycamore trees early in the spring causing of the disease will be serious. a rapid wilt of newly emerging leaves. This Disease intensity decreases as the average • The first symptoms appear on rapid wilting is frequently misidentified temperature increases from 55 to 60 degrees. young leaves as they unfold. as frost damage. Larger, more mature Little or no anthracnose will occur if average • Older leaves turn brown, leaves develop a brown growth along the temperatures during this susceptible stage are main veins. Infected leaves often curl and above 60 degrees. and dead areas occur along eventually fall, littering the ground. The the leaf veins. Brown areas fungus involved is Apiognomonia errabunda eventually enlarge to include & veneta (synonyms = Gnomonia errabunda Treatment the whole leaf. & veneta); anamorphs = Discula umbrinella Apply sprays as buds begin to swell. • The ends of twigs may be & platani. During rainy springs additional applications The sycamore leaf is naturally fuzzy. are needed at 7 to 14 day intervals until killed back 8 to 10 inches. Do not confuse this natural fuzziness with conditions for this disease are no long • Cankers may develop on the infection by anthracnose fungus. favorable (see Weather Influences above). tree trunk and main branches. A second crop of leaves may be Cankers produced from mid-June into July after loss of the first set. Protect this second set of Cankers often form on the twigs leaves with fungicide sprays if cool, moist and branches at the base of blighted leaf conditions exist. clusters. Cankers restrict water and nutrient Fungicides registered for the control of movement to the leaves resulting in twig sycamore anthracnose include chlorothalonil die-back, chlorosis and scorch on leaves, and (Daconil Zn, Daconil Ultrex and Daconil even kill larger branches. These cankers are Weather Stik. REI = 12 hours), thiophante- active during wet cool springs and produce methyl (3336TM F and 3336TM WP. REI = 12 spores that spread to neighboring twigs, hours), and copper fungicides. Champion leaves, and other sycamore trees. WP ® and C-O-C-S ® are copper fungicides Cankers also develop in larger branches, approved for organic use. REI = restricted- girdling and eventually killing them. Small, entry interval. Do not enter or allow workers black fruiting bodies of the causal fungus entry into treated areas during this period appear in the discolored bark of dead twigs following fungicide application. The REI and branches. varies with the copper product. Refer to Repeated annual killing of twigs results in labels for specific information. clusters of old dead twigs and live branches The recommended fungicides usually creating what are called "witches’ brooms." are readily available to homeowners at © Colorado State University Extension. 9/98. Revised 12/14. www.ext.colostate.edu

*C.E. Swift, Colorado State University Extension horticulture agent emeritus 10/2011 Reviewed 12/2014. local nurseries and garden centers. planting of the American sycamore should Always read label directions. Labels may be avoided. The Oriental plane, a shorter, be updated yearly or more often. If the less graceful tree, is highly resistant to product label does not include anthracnose anthracnose but rarely grown in the on ornamentals (shade trees), use an United States. The London plane tree alternative product. (P. x acerifolia, synonyms P. x orientalis or P. hybrida) is a cross between the Oriental plane (P. orientalis) and the Cultural Practices highly susceptible American sycamore (P. Gather and destroy all fallen leaves and occidentalis). The London plane cultivars, twigs. They will produce fungus spores the 'Bloodgood', 'Columbia' and 'Liberty' are Figure 1: This sunken dead area (canker) is due to Anthracnose. following spring if not destroyed. resistant to anthracnose and are good Prune out all infected twigs and choices for planting where the sycamore branches and destroy them. Cut out anthracnose fungus is a problem. cankers in large limbs to reduce reinfection. Remove the dead, cankered tissue down to healthy wood. References Dry winters weaken trees, increasing the Dickman, M.B. 2001. Anthracnose. Page effects of diseases. To reduce this problem, 43, in: Maloy, O.C., and Murray, T.D. water trees once a month during snowless eds. Encyclopedia of Plant Pathology, winters. Water when air temperatures are John Wiley & Sons, Inc., New York, NY. above freezing and early enough during Hartman, J. 2001. Sycamore and planetree the day to allow water to soak in before diseases. Pages 355-359, in: Jones, nightfall. For more information on winter R.K. and Benson D.M. eds. Diseases watering, see fact sheet 7.211, Fall and of Woody Ornamental and Trees in Winter Watering. Nurseries. APS Press, St. Paul, MN. Figure 2: The 'witches broom' is where In the spring after leaf emergence, Sinclair, W.A., Lyon, H.H., and Johnson, numerous shoots grow from the same point. apply nitrogen around trees suffering W.T. 1987. Diseases of Trees and Shrubs. from repeated attacks of anthracnose. This Cornell University Press, Ithaca, NY. nitrogen application should be based on a 574 pages. soil test (see www.ext.colostate.edu/pubs/ Influence of Environment and Inoculum garden/xcm222.pdf). A yearly application Density on Penetration and of nitrogen will stimulate growth and Colonization of Sycamore Leaves by help anthracnose-infected trees recover Apiognomonia veneta. Ammon, V., from loss of leaves, twigs and branches. Graves, B. and Griffin, D. Plan Dis. 74:989-991.

Resistance The American sycamore (Platanus occidentalis L) is much more susceptible to anthracnose than the London (Platanus Figure 3: This canker has several fruiting bodies x acerifolia) and Oriental plane (Platanus poking through the dead tissue. orientalis). Due to this high susceptibility,

Colorado State University, U.S. Department of Agriculture and Colorado counties cooperating. CSU Extension programs are available to all without discrimination. No endorsement of products mentioned Figure 4: Note the pimple-like structures, fruiting is intended nor is criticism implied of products not bodies, on this stem. mentioned.