Management of Large Patch Disease in Turfgrass:
Emphasis on Fall Activities
Alfredo Martinez & Lee Burpee
Plant Pathologuy, University of Georgia
Large patch disease of turfgrass is most common in the fall and in the spring as warm season grasses are entering or leaving dormancy. Large patch is caused by the fungus Rhizoctonia solani. It can affect zoysiagrass, centipedegrass, St. Augustinegrass and occasionally bermudagrass.
Symptoms of this turfgrass disease include irregularly-shaped weak or dead patches that are from 2 feet to up to 10 feet in diameter. Inside the patch, you can easily see brown sunken areas. On the edge of the patch, a bright yellow to orange halo is frequently associated with recently affected leaves and crowns. The fungus attacks the leaf sheaths near the thatch layer of the turfgrass.
These photos show large patch in centipede (left top), Bermuda (right top) and zoysia (below).
Large patch disease is favored by:
Cultural practices are very important in control. Without improving cultural practices, you may not acheive long term control.
- Thick thatch
- Excess soil moisture and poor drainage
- Too much shade which stresses turfgrass and increases moisture on turfgrass leaves and soil
- Early spring and late fall fertilization
- Use low to moderate amounts of nitrogen, moderate amounts of phosphorous and moderate to high amounts of potash. Avoid applying nitrogen when the disease is active
- Avoid applying N fertilizer before May in Georgia. Early nitrogen applications (March-April) can encourage large patch
- Water timely and deeply (after midnight and before 10 AM). Avoid frequent light irrigation. Allow time during the day for the turf to dry before watering again
- Prune, thin or remove shrub and tree barriers that contribute to shade and poor air circulation. These can contribute to disease
- Reduce thatch if it is more than 1 inch thick
- Increase the height of cut
- Improve the soil drainage of the turf
- Apply lime if soil pH is less than 6.5
A myriad of fungicides are available to control the disease. Consult the current Georgia Pest Management Handbook.
Timing of fungicide application is important. Late September or early October and repeating the application 28 days later are effective for control of large patch during fall. Fall applications may make treating in the spring unnecessary. Always follow label instructions, recommendations, restrictions and proper handling.
See the current Georgia Pest Management Handbookfor more information. Check fungicide labels for specific instructions, restrictions, special rates, recommendations and proper follow up and handling.
Please share this information with others in the landscape & turf industry. For more information:
Call your local Extension Agent at (800) ASK-UGA1 or locate your local Extension Office at http://www.caes.uga.edu/extension/statewide.cfm
Armyworms in Pasture and Turf - http://wiki.bugwood.org/Armyworms_in_Pasture_and_Turf
Fall Armyworms - https://secure.caes.uga.edu/urbanag/Home&Garden/indexFS.cfm?storyid=2576
Pest Management Handbook (Follow all label recommendations when using any pesticide) - www.ent.uga.edu/pmh/
For more Landscape Alerts please visit the Georgia Center for Urban Agriculture