Is It Time To Kill The Ryegrass?

By Brian Whitlark, Agronomist
June 3, 2010

Although I was happily surprised when I opened my electrical bill this month, I noticed the average temperature for May 2010 in Phoenix, AZ was a chilly 75.1 degrees, compared to May, 2009 at 84.6 degrees. At a recent seminar on transition, Dr. Leah Brilman noted that turf managers may employ many strategies to expedite bermudagrass transition, but the number one factor influencing bermudagrass growth and recovery is the weather. Before you pull the trigger on that chemical application to remove the overseeded turf, consider the following points:

  • Bermudagrass growth and recovery is more likely in the following conditions:
    • When the low air temperature is greater than 60̊ F for five consecutive nights.
    • When soil temperatures, collected at the 4-inch depth at 11am, exceed 65̊ F.
    • In the absence of a good soil thermometer, a good rule of thumb (offered by Dr. David Kopec) is to add the high and low temperature for the day and divide by two, which is often very close to the soil temperature.
    • Soil temperatures in the higher cut roughs will often be substantially cooler than lower cut areas, and further strengthens the argument to lower rough mowing heights in the spring.
  • Consider delaying the chemical removal of your overseeded grass for several weeks. Larry Stowell, from PACE Turf recommends spraying when the average air temperature reaches 65 degrees and/or soil temperatures reach 70 degrees or higher at the 6inch depth.
  • In southern AZ and Palm Springs, the optimal time to spray out this season may be mid to late June. In southern NV, it may be late June to early July.
  • A later spray date allows for lower chemical rates while still offering complete removal of the overseed. A spray too early requires a full rate, which may delay bermudagrass recovery.
  • Don’t be shy with nitrogen. Soluble nitrogen at this time of year stresses the overseeded grass and will expedite bermudagrass recovery.

This year, more than any other, will NOT likely offer a seamless transition. You must nurture the relationships you have with the pro shop staff, general manager, board members and golfers and educate them on why this transition may be poor, even though you employed all the right management strategies.

Source: Brian Whitlark, or 480-215-1958

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