WHAT QUALIFIES TURF-SEED VARIETIES AS GRAY LEAF SPOT-RESISTANT?

Gray leaf spot (Pyricularia grisea), another fungus-born disease, has a high incidence rate in the mid-Atlantic and transition zone areas, where perennial ryegrass (Lolium perenne) has been extremely susceptible. To help turfgrass managers battle gray leaf spot, researchers at Pure-Seed Testing, Inc., in Rolesville, N.C. conduct ongoing trials that expose perennial ryegrass to heavy gray leaf spot pressure.

The varieties that perform in the top 12% of those trials show good-to-excellent gray leaf spot resistance, with 60-100% live mature turf after being subjected to high levels of the disease pressure. The majority of commercially available perennial ryegrass varieties do not survive these trials.

Research & Breeding Work

Pure-Seed Testing, Inc. identifies perennial ryegrass varieties with increased gray leaf spot resistance for use in breeding projects. Outbreaks tend to occur later in the plant’s development, for example, in mature turf trials during their ninth to twelfth months. Of 43 commercially available varieties evaluated in 2004, 38 (88%) rated below 2.0 for gray leaf spot damage. This is based on a scale of 1-9, where 9 = no disease and 1 = dead. In 2005, 88% of varieties rated below 4.0. Each year, perennial ryegrass survivors from the Pure-Seed, Inc. test trials in North Carolina are in the top 12% of surviving test plots.