Susceptible Turfgrasses:
Zoysiagrass
St. Augustinegrass
Centipedegrass
Kikuyugrass
Seashore paspalum
Identification:
Large Patch primarily affects the basal leaf sheaths of warm-season grasses. Key symptoms include:
Early Lesions: Small reddish-brown or black lesions on basal leaf sheaths.
Patches and Rings: Develops into rings or patches of blighted turf, ranging from 5 inches (13 cm) to over 10 feet (3 meters) in diameter.
Color Variations: Patches may appear reddish-brown to yellow, with potential “orange firing” at the edges.
Leaf Detachment: Damaged leaves easily detach when pulled.
Seasonal Effects:
During winter, blighted patches contrast starkly with healthy dormant turf.
In bermudagrass, symptoms may manifest after spring greenup, primarily affecting the leaves.
Favorable Conditions:
Large Patch thrives under the following conditions:
Timing:
Most prominent in fall and spring during the transitions of warm-season grasses.
Weather Conditions:
High humidity and cool/cold temperatures.
Extended periods of overcast skies and rainy weather.
Additional Risk Factors:
Shady Areas: Turf in shaded areas is more susceptible.
Poor Drainage: Sites with poor drainage increase the risk of infection.
Fine-Textured Zoysiagrass: Certain fine-textured cultivars of zoysiagrass are particularly vulnerable.
Management Tips:
Water Management: Improve drainage and avoid excessive irrigation during fall and spring.
Aeration: Aerate compacted soil to enhance water infiltration and reduce standing moisture.
Fertilization: Avoid late-season nitrogen applications, which can encourage susceptibility during transitional periods.
Mowing Practices: Raise mowing heights in fall and spring to reduce turf stress..
Vertical Cutting: Vertical cutting affected zoysiagrass after 100% green-up and spoon-feeding (~ 0.25 lb N/1,000 ft2.) helps speed recovery if there are numerous surviving plants in patches. Severely damaged areas may have to be sodded.
Promote sunlight and air circulation, and improve surface water drainage.