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Rust1
M. L. Elliott and G. W. Simone2Rust
- Pathogen: Puccinia spp.
- Turfgrasses Affected: St. Augustinegrass and zoysiagrass; it may also be observed on perennial ryegrass used to overseed lawns in the winter months.
- Occurrence: This disease can occur from late fall to early spring when the turfgrass is not growing rapidly due to cool weather. It will be more severe on turfgrass areas that are stressed from nutrient deficiencies or shade (ex: under trees, north side of building). The leaves must be wet for infection to occur. This wetness may be from dew, high humidity, rain or irrigation.
- Symptoms/Signs: Initially, light yellow flecks will appear on the leaves. If the disease progresses, these flecks will enlarge into spots that are parallel to the leaf vein. Eventually, orange pustules (spots) will form containing spores ( Plates 19 and 20 ). These pustules will also be parallel to the leaf vein. The spores will rub off on your fingers. Heavily infected areas will appear thin and chlorotic (yellow to light brown).
CREDITS: G. W. Simone
Plate 19. Rust symptoms on zoysiagrass.
CREDITS: G. W. Simone
Plate 20. Rus symptoms on ryegrass. Orange spores will rub off.
- Cultural Controls: Maintain an adequate, balanced fertility program using slow-release nutrient sources. In shady areas, monitor the irrigation closely to keep the leaves as dry as possible. In most situations, the disease will disappear as soon as the weather warms and the turfgrass starts to grow vigorously again. The disease may cause the turfgrass to look ugly, but it will not kill the turfgrass.
- Chemical Controls: azoxystrobin, mancozeb, propiconazole, thiophanate methyl, triadimefon, trifloxystrobin.
- Mancozeb can be applied to a residential lawn only by a professional pesticide applicator.
- Refer to "Turfgrass Disease Management" section of the Florida Lawn Handbook for explanation of cultural and chemical controls.
Footnotes
1. This document is SS-PLP-12, a series of the Plant Pathology Department, Florida Cooperative Extension Service, Institute of Food and Agricultural Sciences, University of Florida. This information is included in the Florida Lawn Handbook, SP-45. For a copy of this handbook, request information on its purchase at your county extension office. First published: May 1991. Revised: April 2001.2. M. L. Elliott, Associate Professor, Plant Pathology, Fort Lauderdale Research and Education Center, and G. W. Simone, Emeritus Professor, Plant Pathology Department, Cooperative Extension Service, Institute of Food and Agricultural Sciences, University of Florida, Gainesville, FL 32611.
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U.S. Department of Agriculture, Cooperative Extension Service, University of Florida, IFAS, Florida A. & M. University Cooperative Extension Program, and Boards of County Commissioners Cooperating. Larry Arrington, Dean.
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