Ground Ivy Rust

We are interested in the incidence of a new rust fungus that attacks the common weed, ground ivy (Glechoma hederacea). The fungus is a native of Europe and was first found in North America by M. Scholler in 2000. It occurs throughout the northeastern states and appears to be spreading--its distribution has been established by Scholler & Boellmann through herbarium studies. The fungus is potentially interesting as a biocontrol of this invasive weed. We could use your help to determine how frequently this pathogen occurs in the US, and how much control it exerts over groundivy in yards and turf in your neighborhood.

Introduction

Ground ivy or creeping Charlie (Glechoma hederacea L., shown below) is a creeping perennial in the Labiaceae or Mint Family that forms dense prostrate patches in turfgrass, damp shady meadows, and disturbed sites (Uva et al., 1997). This plant can also colonize areas exposed to full sunlight. Reproduction is primarily by creeping stems (i.e., stolons) that root at the node and less commonly via seed and rhizomes. Ground ivy is native to Eurasia but has been introduced and become widespread in North America. The control of ground ivy using chemical and mechanical methods has largely been unsuccessful in turfgrass where it is considered a major weed (Mitich, 1994; Turgeon, 1994; Lamboy et al., 2000). Effective and environmentally sound approaches are needed for the control of ground ivy in turfgrass.

The rust is called Puccinia glechomatis. It forms very small tan dots on the undersides of ground ivy leaves and stems. A severe infection can cause death of a whole leaf segment or an entire stolon and all its leaves. The fungus spreads via spores (shown in the background of this page) and appears to be highly specific to ground ivy. Its ability to infect related plants needs further testing.

Very few other diseases of ground ivy are known in North America. Large galls of the leaves and stem, caused by a parasitic wasp, are fairly common. The galls do not appreciably diminish plant growth, so the wasp is not a good candidate for biological control. Although we are not interested in receiving galls or other damage done by feeding insects, we will gratefully accept other diseases of ground ivy for identification.

How to help

If you think you have found this rust, we would be grateful to receive documented samples for confirmation. Please follow the mailing instructions on the right side of this page.

Cornell Plant Pathology || Horticulture || Weed Ecology

Drs. Leslie Weston(Horticulture), Toni DiTommaso (Weed Ecology), and Kathie Hodge (Plant Pathology) are studying Puccinia glechomatis as a potential biocontrol for ground ivy.

Others working on this rust can be found at Purdue, USDA-ARS Frederick, and UCA.

References

Healthy ground ivy plants (below). Click here to view diseased plants.

This page maintained by K.T. Hodge. Photographs on this page are © Cornell University, but may be reproduced for nonprofit educational purposes.

click for a larger view of this and other images

How to send us plants

• Harvest leaves with their attached stems and a short piece of the stolon
• Press the plants in a phone book or plant press for a day or more
• Enclose the pressed plants in a legal-sized envelope. Fold them if necessary. Do not enclose in plastic, which promotes mold growth
• Include a scrap of paper with the date and location (state, county, town and site) where you collected the plants. Tell us what kind of habitat they came from (e.g. lawn or edge of woods)
• Include your observations on the extent of disease in your area, if possible
• Include your mailing or email address (optional)
• Mail by standard US mail to the following address:
  

  Dr. Toni DiTommaso

  Dept. of Crop and Soil Sciences

  903 Bradfield Hall

  Cornell University

  Ithaca, NY 14853

  email: ad97@cornell.edu

   

• DO NOT mix plants from different locations
• DO NOT send damp plants
• DO NOT mail plants from outside the continental USA
• DO NOT send plants that were recently sprayed with pesticide

Specimens that we receive in good shape and with adequate documentation will be archived in the Cornell Plant Pathology Herbarium.