For the most part, late spring and early summer this year has been reasonable, weather-wise. So goes the weather, so goes the turfgrass. So far, the turfgrass submissions to the Plant Diagnostic Laboratory have been slow and steady… until last week, that is. Golf turf suddenly realized it was summer and the party started with some dollar spot.
Dollar spot sample. You know things are crazy in the field when we get samples of dollar spot from golf guys! Photo: Sabrina Tirpak, Rutgers PDL
My personal highlights, however, were the samples of Pythium blight that arrived mid-week. Day and night temperatures above 85ºF and 70ºF, respectively, and relative humidity above 90% for at least 14 hours are generally required to get Pythium blight cranking. Dr. Phil Halisky used to tell me that we needed three consecutive days with relative humidities and temperatures above 150 for Pythium outbreaks to occur. Whichever way you slice it, we had those conditions almost every day last week and in came the Pythium samples.
Pythium blight on perennial ryegrass. Photo: Sabrina Tirpak, Rutgers PDL
Distinquishing Pythium from dollar spot is as easy as making a slide (although, field symptoms are pretty telling). Pythium species have hyphae with no (or very few) cross walls and rapidly produce an abundance of reproductive propagules. The dollar spot fungus is sterile and has plenty of cross walls.
Pythium spp. hyphae and reproductive propagules (oogonia). Photo: Sabrina Tirpak, Rutgers PDL
Summer patch also arrived right on schedule. The conventional wisdom is that summer patch exhibits symptoms around Independence Day. We made our first diagnosis of the disease on samples submitted last Wednesday – right in time for the holiday weekend!
Summer patch in Kentucky Bluegrass lawn. Photo: Jim Matkovich, SavaLawn
Of course, the “fuzz” associated with summer patch is not visible, because it is on the roots of infected grass plants and not in the foliage. Once in the laboratory, however, a trained eye can easily identify the pathogen.
Darkly pigmented ectotrophic hyphae of Magnaporthe poae, the cause of summer patch in Kentucky bluegrass. Photo: Sabrina Tirpak, Rutgers PDL
Can’t make an early summer golf turf disease post without a shot of anthracnose. The numbers of anthracnose samples submitted to the Plant Diagnostic Laboratory have declined over the years as research scientists and graduate students developed best management practices for anthracnose management. Despite our best advice, many Rutgers Plant Diagnostic Laboratory clients push the limits of their grass and wind up with a little disease action.
Annual bluegrass with both a foliar and basal anthracnose infection. Photo: Sabrina Tirpak, Rutgers PDL
And lastly, nothing like a little gratuitous bug sex to celebrate the beginning of golf turf “silly season!”
Pile of Japanese beetle adults on the turfgrass. Photo: Corey Randall, Lancaster Country Club
We’re off to the races. Now go on out and kill a putting green for me… hope to see ya between now and field days!
