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You Are
Here: Management Updates
Date: June 6, 2006 With the arrival of warmer weather, as well as the dry conditions of
early spring, the UMass
Extension Plant Diagnostic Lab Necrotic Ring Spot, caused by Ophiosphaerella korrae, is primarily a disease of Poa species. Infection centers that develop in the fall may persist through the winter and into early spring. In fact, the lab received a specimen in mid-January (during the crazy early spring-like weather) with symptoms so classic that the specimen was used for teaching purposes in Winter School. Patches often have a frog-eyed appearance, with healthy bent appearing in centers and recovery is slow. Fertilization with slow release forms of nitrogen, addition of biological controls like TurfRestore™ to stimulate natural microflora, and light daily irrigations can help turf recover. Cultural practices which encourage deep rooting such as improving drainage, reducing compaction, and aerification can aid in disease control. Thiophanate-methyl, fenarimol, iprodione, and propiconazole fungicides thoroughly watered in are control options. Take-all, caused by Gaeumannomyces graminis, is most serious on newly established bentgrass greens. Take-all is favored by high pH and its severity can be reduced by acidifying fertilizers like ammonium sulfate. Be sure to apply with care and water in to avoid high salt injury. Soil conditions that favor the pathogen include light soil texture, low organic matter, and manganese deficiency. Manganese sulfate applied at 1-2 lb Mn/A can reduce the severity of Take-all. Chemical control options include azoxystrobin, fenarimol, propiconazole, and triadimefon applied after the first mowing, followed by an application in 30 days. Fungicides may need to be applied again in late summer as night temperatures fall below 50 ˚ F. This disease generally peaks in 3-5 years and then gradually declines due to the build-up of antagonistic microflora. Summer Patch, caused by Magnaporthe poae, is a serious disease of bluegrass that generally appears after the soil temperature reaches 70˚ F and after heavy rains or irrigation. Management of Summer Patch consists of light, frequent applications of slow release forms of nitrogen, maintaining a soil pH between 5.5-6.0, and annual applications of manganese sulfate. Aerifying, improving drainage, reducing compaction will reduce disease severity as will raising the mowing height during the summer stress period. Syringing can help nurse the turf through a disease outbreak. Azoxystrobin, propiconazole, and thiophanate methyl fungicides manage summer patch best. Repeat applications may be needed.Submitted by: M. Bess Dicklow DISCLAIMER - As always, it is the responsibility of the applicator to verify the registration status of any pesticide BEFORE applying it. Different states have different regulations as well. The author and the University of Massachusetts are not liable for any consequences of any pesticide "recommendations". Mention of any trade name is not to be considered endorsement of a product. |
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has
begun to see patch diseases caused by root-infecting ectotrophic fungi.
All these diseases are active in the cool, wet weather of spring and
fall; symptoms often appear in the warmer weather of late spring and
summer or whenever water stress occurs.
