David M. Kopec, Extension Turfgrass Specialist
Switching back from ryegrass to bermudagrass is the timely topic for homeowners and landscapers in June and early July. There are many "home remedies" to try to speed this along. Some of them are good tricks, while others are bad. Most homeowners want to drastically get rid of the bermudagrass by either scalping the lawn, or drying the lawn out by turning off the water for one week.
Either of these will have a drastic effect on the appearance of the lawn, causing an "uneven" or "forced transition"! In the old days, you could scalp ryegrass in the late spring, and the scalping stress would severely weaken the ryegrass. At the Karsten Turfgrass Facility, we are in our second summer of testing scalping techniques coupled with different nitrogen fertilization applications in order to "force" the transition back to bermudagrass. The problem that has developed in the last ten years, is that many of the ryegrasses sold have much better heat tolerance, and persistency than previous varieties. They last longer in the early summer, and tolerate close mowing, and scalping to some extent. Note that if you scalp, you will scalp the underlying bermudagrass, as well. This occurs more so on common bermudagrass, than Tifway or Santa Ana. If you scalp, do it for 2-3 mowings, then mow as normal for the bermudagrass.
Shutting of the water will injure the ryegrass, but also drastically slows the "new" bermudagrass underneath as well. All winter and spring, the bermuda has been kept wet, even though it has been sleeping. Therefore, the bermudagrass is not drought hardy, compared to unwatered and non-overseeded bermudagrass. The sudden "drying out" of the bermudagrass will slow its regrowth, and thus have a slow transition also.
The ryegrass eventually becomes less competitive when the weather becomes humid, and the high night-time temperatures occur. This is usually mid-July (monsoon). At this point, the ryegrass is using up food reserves, both day and night. The end is near for the ryegrass. So, here's the scoop.
Delicate Transition: (Minimal loss of turf quality)
*Drop mowing height slowly for the normal height of the bermuda
(Common or seeded type 1¼" - 1½", Tifway " - ").
*Fertilize with nitrogen ½ - lb-N-/M every two weeks, until lawn is 90% bermuda.
Then apply ½ lb every three weeks, until early fall.
*Irrigate normally, do not let the lawn dry out.
Forced Transition: (Temporary Loss of Turf Quality)
*Fertilize the lawn with 1½ lbs-N-/M and water it in.
*Scalp the lawn.
*Let the lawn grow "up" again. Maintain irrigation.
*Scalp the lawn again.
*Shut off the water for five to seven days.
*Re-apply ½ - 1 lbs. of nitrogen/m. water in.
*Maintain normal mowing height for bermuda.
*Return to normal irrigation program.
Other things equal:
Annual ryegrass fades away much quicker than perennial ryegrass, since it is less heat tolerant in the late spring.
Tifway, Santa Ana and other low cut hybrids (all mowed at ¾"
or less) will have a better transition, than that of common bermudagrass
and other "like" seeded type bermuda's.
Issued in furtherance of Cooperative Extension work, acts of May 8 and June 30, 1914, in cooperation with the U.S. Department of Agriculture, James A. Christenson, Director, Cooperative Extension, College of Agriculture & Life Sciences, The University of Arizona. The University of Arizona is an equal opportunity, affirmative action institution. The University does not discriminate on the basis of race, color, religion, sex, national origin, age, disability, veteran status, or sexual orientation in its programs and activities.