Take-All Patch of Bentgrasses
Take-all patch caused by Gaeumannomyces graminis (formerly Ophiobolus graminis) is a serious disease of all species of bentgrass in temperate climates throughout the world. It is most severe on newly established creeping bentgrass turfs. Symptoms appear in late spring or early summer as small, circular, light brown to reddish brown patches. Symptoms may persist throughout the summer, reappear in successive years, and can reach diameters of 3 ft or more. Patches may coalesce into large areas of dead or dying turf and the affected areas heal slowly. The centers of patches are often invaded by weeds, fescues, or bluegrass species. Symptoms may intensify with the onset of summer stress, with bronzed turf fading to a dull brown; affected areas may appear gray in the winter. The roots, rhizomes, stolons, and crowns turn dark brown to black with black ectotrophic hyphae on the surface of the roots. Fruiting bodies (perithecia) of the pathogen develop beneath the leaf sheaths around crowns in late spring or autumn.
G. graminis survives as mycelium in infected plant debris and invasion of hosts occurs during the autumn and the spring. Initially, the fungus colonizes the surface of the roots, but under favorable conditions (cool, moist weather) root interiors are infected and extensive colonization occurs. Take-all patch is most severe in sites with a high sand content, or recently fumigated soils. The pathogen is favored by low fertility, high pH, manganese deficiency, and cool, wet weather followed by hot, dry conditions. In some cases, take-all patch declines in severity after several years, presumably because of the activity of antagonistic microflora.
- Plant resistant cultivars. Cultivars of A. stolonifera with moderate levels of resistance are available. Planting a mixture of bentgrass with fine-fescues also may reduce disease severity.
- Maintain soil pH below 6.5, preferably between 5.5 and 6.0.
- Make light, frequent applications of fertilizer to compensate for root damage.
- Avoid excessive levels of nitrogen. Provide adequate levels of phosphorous and potassium.
- Avoid nitrate forms of nitrogen. Use acidifying fertilizers such as ammonium sulfate or urea based nitrogen sources being careful to avoid foliar burn.
- Where manganese is deficient, apply 2 lb/acre in the spring or fall. Apply manganese in high spray volumes to ensure thatch penetration.
- Irrigate deeply and frequently while avoiding moisture stress.
- Improve surface and subsurface drainage.
- Reduce thatch and aerify to reduce soil compaction. Do not perform these activities when disease is active.
Management with Fungicides
Fungicides should be applied in at least 5 gal water/1000 sq ft or followed immediately (before drying) with 0.125-0.5 inch of irrigation to move the fungicide into the root zone. The best time to treat Take-all preventively is from mid-September-early November (soil temperatures at 2 inch 45-60°F). Where there is severe disease pressure, fungicide applications may be required in spring as well. Curative applications in summer have been reported to hasten recovery.
For a listing of fungicides currently labeled to manage this disease, refer to the Disease Management chapter of UMass Extension's Professional Guide for IPM in Turf for Massachusetts.
Written by: M. Bess Dicklow