RUST ON TURFGRASS Puccinia and Uromyces spp.   F A C T S H E E T

Introduction

All turfgrass species are susceptible to rust diseases. Environmental stresses contribute to the severity of the disease. When plants become diseased by the rust fungi, they are more likely to be attacked by other pathogens.

Symptoms

Figure 1: Orange pustules covering the leaf blades. (provided by Eric B. Nelson, Cornell University)

Figure 2: Yellow/orange discoloration of the turf. (provided by Eric B. Nelson, Cornell University)

Initial symptoms include yellow lesions (Figure 1) that enlarge overtime. When mature, spores break through the epidermis of the lesion area and are blown by wind and splashed by rain to new infection sites. The spores are characteristically orange in color but may vary with yellow, red, or brown coloration. When the disease becomes severe, the turfgrass strands may appear very thin and discolored. Death of the turf is possible during severe infections.

Disease Cycle

Rust pathogens have a very complicated and complex five spore stage life cycle often involving two alternating host plants. The characteristic orange pustules on the leaf blades (Figure 2) is produced by the uredospore stage. This stage is also the repeating stage of the fungus which can cause new infections every two weeks without completing the complex life cycle.

The other spore stages involved in this lifecycle are not harmful to the turfgrass. Two spore stages, pycniospores and aeciospores are found on the alternating host, which is in some cases is Barberry (Berberis sp.). The aeciospores leave the alternate host and infect the turf. Once on the turf the fungus may produce three more spore stages, the uredospore stage which causes the damage to turf, the teliospore stage, and the basidiospore stage which leaves the turf to infect the alternate host.

Management Strategies

Water management is important in controlling the disease. Watering the turf in the early part of the day is recommended to encourage quick drying and minimize the length of time the leaf blades are moist. Also avoiding water-related stresses such as drought and poor drainage. Mowing on a regular basis and keeping the mowing height at recommended levels can help reduce the incidence of disease. Racking up the clippings when the disease is present and discarding or destroying them will reduce the amount of inoculum at the site. Prune surrounding trees to provide more light and greater air flow to the area. Use resistant varieties when available. Some fungicides containing the active ingredients chlorothanonil, propiconazole or triadimefon are available for control.

Updated, SLJ, 1/07

This publication contains pesticide recommendations. Changes in pesticide regulations occur constantly, some materials mentioned may no longer be available, and some uses may no longer be legal. All pesticides distributed, sold, and/or applied in New York State must be registered with the New York State Department of Environmental Conservation (DEC). Questions concerning the legality and/or registration status for pesticide use in New York State should be directed to the appropriate Cornell Cooperative Extension Specialist or your regional DEC office. READ THE LABEL BEFORE APPLYING ANY PESTICIDE.
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The Plant Disease Diagnostic Clinic at Cornell University is located at 334 Plant Science Building, Ithaca, NY, 14853. Phone: 607-255-7850, Fax: 607-255-4471, Email: kls13@cornell.edu or slj2@cornell.edu.