A new disease of cool season turf was first diagnosed in California in 1995 from Poa annua putting greens. Since that time, the disease has been observed in nine states and in addition to Poa annua, has caused serious damage to large expanses of Poa trivialis and Lolium perenne. The disease has also been observed associated with salt-stressed Agrostis palustris. Symptoms include severe yellowing of turf  (Photo 1) and a water-soaked appearance to the diseased foliage (Photo 2).      Football-shaped structures (4-6 um x 10-12 um) (Photo 3) similar in appearance to sporangia of chytridiomycete fungi can be observed inside leaf cells of symptomatic plants (Photo 4). All attempts to isolate a fungus from infected tissues have failed. However, the disease was reproduced in Poa trivialis seedlings grown in pots containing soil from a golf course that contained diseased Poa annua plants. Preliminary field trial results indicate that the fungicides mancozeb, trifloxystrobin, or pyraclostrobin provide some measure of prevention or control.

     Rapid blight has been diagnosed in several southeastern and western states in recent years. An unidentified fungus that appears similar to those in the Chytridiomycetes has been consistently associated with the disease in Poa trivialis, Poa annua, Lolium perenne, and (rarely) Agrostis stolonifera. The disease occurred in South Carolina in spring as well as fall months of 2000 and 2001, and was consistently  associated with sites with poor quality irrigation water: high salinity and sodicity, high bicarbonate concentrations. Experiments have shown some suppression of the disease, associated with improved establishment of Poa trivialis, from treatments with Compass (trifloxystrobin), Insignia (pyraclostrobin) (Photo 5, Figure 1), or Fore Rainshield (mancozeb) (Figure 2). Other fungicides have not been shown to be effective to date. Experiments are continuing on this new and potentially devastating disease.