You know it's a bad sign when you get to your office and there is a superintendent waiting by your office door with a sample in hand - this is how this week started and the calls and emails just kept coming. The reason, yellow rings similar to those seen with yellow patch began showing up on putting greens on Monday and Tuesday. The symptoms look very similar to yellow patch or summer patch (some of those calling in are referring to these symptoms as necrotic ring spot, but we'll discuss this in a minute). Bottom line, we aren't exactly sure what is causing these symptoms. What we do know is that the symptoms are showing up on both Poa annua and bentgrass, there is a considerable amount of Rhizoctonia mycelium on most of the samples, and a lack of darkened roots or fruiting structures that we'd normally associate with the "patch" diseases. Likely suspects based on symptoms would include yellow patch, summer patch or a type of fairy ring.

Although yellow patch can show up with warmer temperatures if there has been heavy rains, this doesnt quite fit with the fact that these symptoms just popped up after a weekend of 85-90 F weather. In fact, some of the courses experiencing symptoms had the heat but missed the rain. The presence of Rhizoctonia mycelium in these samples fits with yellow patch, but the presence of symptoms with the excessive heat is puzzling. All situations to date are on pushup and older greens, if new sand greens are on the course they have not been affected. The primary turfgrass affected is Poa annua however there have been reports on creeping bentgrass. In most cases the lack of any ectotrophic runner hyphae on the roots and crowns of the plants steers one away from calling this summer patch. The final option is that the symptoms are being caused by some type of fairy ring fungus - which although rare for us in Ohio at this time of the year, is not outsided the realm of possibilities. We are working the issue and will provide information as it becomes available.

Strange and unusual weather patterns may be a major factor in the development of these symptoms. With the mild conditions in the winter and wild fluctuations in both temperatures and rainfall throughout the spring unusual growth of soil fungi could result which have lead to the symptom patterns now being experienced on turfgrass. Treatment options for those feeling the need to do something. First option - wait and see - especially given the recent change in the weather. Second option - spray. Heritage® and Prostar® are two fungicides that we typically recommend for all three diseases. Follow the label, use the high rate and, perhaps most important, apply the fungicides using 4 gal/1,000 ft2 - we are targeting a crown/root pathogen and must get the fungicide into the rootzone.

Necrotic ring spot versus summer patch. Before 1984, the only confirmed turfgrass patch disease in North America was take-all patch (formerly known as Ophiobolus blight or patch) caused by Gaeumannomyces graminis var. avenae. Today, at least six different patch diseases of turfgrass are recognized and include: necrotic ring spot caused by Ophiosphaerella korrae (formally called Leptosphaeria korrae); and summer patch caused by Magnaporthe poae; spring dead spot of Bermudagrass caused by Ophiosphaerella narmari (formally called Leptosphaeria narmari), O. korrae and O. herpotricha (Gaeumannomyces graminis var. graminis has also been associated with spring dead spot in the southeastern U.S.); Bermudagrass decline caused by Gaeumannomyces graminis var. graminis; and dead spot caused by Ophiosphaerella agrostis.

Patch Diseases on Turfgrass

Take all patch (creeping bentgrass / St. Augustinegrass) Gaeumannomyces graminis var. avenae

Necrotic ring spot (Kentucky bluegrass) Ophiosphaerella korrae (formally called Leptosphaeria korrae)

Summer patch (Poa annua / Kentucky bluegrass) Magnaporthe poae

Spring dead spot (Bermudagrass) Ophiosphaerella narmari (formally called Leptosphaeria narmari) O. korrae, O. herpotricha, Gaeumannomyces graminis var. graminis (southeastern U.S.)

Bermudagrass decline (Bermudagrass) Gaeumannomyces graminis var. graminis

Dead spot (creeping bentgrass and Bermudagrass - sand-based greens and tees ONLY) Ophiosphaerella agrostis