Plant Pathology News and Information:
Take-all Patch of Turfgrass of Golf Courses
Take-all disease is caused by the fungus Gaeumannomyces graminis. The fungus is soilborne and infects through roots, stolons and the crown area. It affects bentgrass (Agrostis sp.), fescue (Festuca sp.), and Poa spp. The symptoms usually appear in late spring to early summer and consist of small round patches or rings that are light to reddish brown. The patches can persist throughout the summer and recur year after year. They can enlarge by up to 6 inches per year. The grass in the patches recovers very slowly and weeds are often seen invading the dead areas. The symptoms are most obvious during hot, dry weather when plants are stressed.
A diagnostic characteristic that can be seen under the dissecting microscope is ectotrophic, dark fungal hyphae on the roots, stolons, or crowns. Hyphopodia, which are small dark fungal structures through which the fungus penetrates the plant, can only be seen with a compound microscope.
The disease is favored by high sand content in the soil, low organic matter, low fertility and pH above 6.5. It is also more common when golf course turfgrass is planted on fumigated sites or recently cleared natural areas like forests. The reason for higher disease levels in recently fumigated sites is the lack of antagonistic microorganisms that compete with Gaeumannomyces or attack it. When testing soil pH, it is more important to test the pH in the rhizosphere (root zone) rather than the pH of the entire soil. Liming the soil can also increase the disease.
|Ectotrophic hyphae on Bermuda grass (left), and hyphopodia (right) are both signs (fungal
structures) of the disease, take-all patch of turf, caused by Gaeumannomyces graminis.
To control take-all patch, an integrated approach is necessary. Mixtures of bentgrass with Festuca rubra can reduce the disease severity. When fertilizers are applied, use acidifying fertilizers such as ammonium sulfate instead of nitrate based fertilizers and avoid manganese deficiency. Root growth restrictions due to too much water or high nitrogen applications should be avoided. Removing thatch can reduce not only take-all patch but also other fungal diseases that survive in the thatch. Fungicides should to be applied either in the fall before dormancy or in early spring to be effective. Effective fungicides that treat take-all patch include Banner Maxx II, Insignia, and Heritage. This disease rarely occurs in residential lawns.
-Claudia Nischwitz, Extension Plant Pathologist