PACE Turf - Turfgrass Information Center


Got gray leaf spot? Then you can help

Gray leaf spot is a devastating summer disease of reygrass, fescue St. Augustine and kikuyugrass in many parts of the U.S. It's hard to think of anyone who might want to actually see it in action, but there are indeed a few dedicated scientists at the USDA and Kansas State University who would be glad to receive samples of this dread disease.

It's all because gray leaf spot, which is caused by the fungus Magnaporthe grisea (also known as Pyricularia grisea) is closely related to a serious disease of rice and wheat known as rice blast or wheat blast, and caused by the fungus Magnaporthe oryzae. Your samples of gray leaf spot-infested turf will help plant breeders to develop new strains of wheat that are resistant to the disease.

If you'd like to help out in this project, please consider sending turf samples (a cup cutter sample placed inside a securely closed zip-lock plastic bag, and then placed in a sturdy box) that are infested with gray leaf spot to: Dr. Gary Peterson, USDA ARS, 1301 Ditto Ave., Frederick, MD 21702. You can contact Dr. Peterson here.

It's very important to enclose this permit with your shipment. Please print it out and include it with your sample in the shipment.

We encourage you to participate in this important project. It would be nice to know that there's some good associated with this awful pathogen...

Nematodes: the number don’t lie (or do they?)

The research study and report, "Impact of Plant Parasitic Nematodes on the Quality of Golf Course Greens" was conducted and written over 20 years ago, but still has significant applications today. It shows that although plant parasitic nematode numbers can very often reach very high levels, most nematodes have very little impact on turf quality — especially if turf is otherwise healthy.

While there are some exceptions to these observations (see this PACE Turf Update on "Status and Control of Nematodes"), it is important to remember that because healthy turf frequently supports higher levels of nematodes than struggling turf (probably due to much greater root mass, and therefore greater sources of food for nematodes), nematode counts can be very deceiving.

In the 22 California golf courses that were surveyed in this study, we found six different genera of nematodes including (nematode names followed by the asterisk, *, were the most commonly found nematodes):

  • Criconemoides* (ring nematode)
  • Helicotylenchus* (spiral nematode)
  • Meloidogyne* (root knot nematode)
  • Paratylenchus (pin nematode)
  • Trichodorus (stubby root nematode)
  • Tylenchorhynchus (stunt nematode)

Read the report, "Impact of Plant Parasitic Nematodes on the Quality of Golf Course Greens"

For more information on nematode biology and management:

Rainfall impact on sodium leaching at Denver Country Club

In the July 13, 2011 Super Journal report, "Rainfall impact on sodium leaching at Denver Country Club" (1.3 MB pdf document), we show the dramatic and positive impact that spring rainfall can have on reducing soil sodium and salinity.

In short, we saw that a 2.5 inch rainfall, which occurred over a 36 hour period during the spring of 2011, resulted in a 41% reduction in sodium, and a 19% reduction in overall soil salts.

In addition to causing general stress to turf and potential issues with soil physical properties, high sodium and high salts are also associated with rapid blight, a disease caused by Labyrinthula terrestris. In years when winter and spring rainfall is low, it may therefore be necessary to leach greens with good quality domestic water in order to avoid reaching the maximum levels of 110 ppm sodium that can result in rapid blight infestation.

Project title: Rainfall impact on sodium leaching at Denver Country Club

Principal investigator: Doug Brooks, Denver Country Club and Larry Stowell, Ph.D., CPAg, PACE Turf LLC

Further reading:

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