Luke Dant, Nick E. Christians and Shui-zhang Fei
Introduction
Roundup® Ready creeping bentgrass (RRCB) could be the golf course superintendent's key to eliminating the invasion of seemingly uncontrollable weed species, particularly Poa annua, in golf course greens and fairways. Roundup® is considered to be a relatively safe herbicide to both the handler and the environment while at the same time providing superior weed control. Additionally, an integrated weed management program based on the use of Roundup® herbicide could be a cost effective alternative to conventional weed control methods.
Unfortunately, the complete renovation to RRCB would be costly and would render a golf course unplayable for a significant period of time. If it was possible to incorporate the overseeding of RRCB into regular maintenance processes, such as verticutting and aerification, existing greens and fairways could slowly be converted to RRCB. This would therefore eliminate costly renovation and the interruption of play.
The overall goal of this project is to determine at what time, in relation to the overseeding of RRCB, that the Roundup® susceptible turf should be removed with Roundup®, so that a successful conversion to RRCB can be achieved. This ideal time would minimize disturbance to the playing surface while still maintaining a satisfactory appearance of the golf course green or fairway.
Site
The study is being conducted at Veenker Memorial Golf Course in Ames, Iowa on one green and three fairways built on native soil. This area was built with the intent to conduct research, therefore, the research plots are not in play. The green is maintained at a height of 0.145 inches and the fairways are mown at 0.60 inches. The research area contains these existing turfgrass species:
Methods
The following treatments where selected in order to accomplish the goal of this study. All treatments were replicated three times on the putting green and three times on each fairway.
It should be noted that during the breeding process, a yield of only 50% RRCB is achieved, whereas the other 50% is conventional bentgrass. The Scotts Company recommends that a Roundup® application be made 4 weeks after seeding to eliminate competition from conventional bentgrass plants that are Roundup® susceptible.
Complete Renovation
Treatment 1 acted as a control in which a bare soil seedbed was prepared. As with the other treatments, RRCB seed was applied at a rate of 1.75 lb per 1000 sq. ft.
Conversion Using Aerificaiton and Verticutting
Green
Treatments 2-11 of the green study were core aerified in two directions using 5/8-inch tines and the aerification cores were harvested. The area was then verticut and topdressed to fill all aerification holes. RRCB seed was applied at a rate of 1.75 lb per 1000 sq. ft. To obtain good soil-to-seed contact the plot was lightly verticut and spiked.
Fairways
Core aerification with 5/8 tines took place on treatments 2-11 in two directions and the cores were broken up using a verticuter. The area was then dragged and seeded at a rate of 1.75 lbs RRCB seed per 1000 sq. ft. As with the green, the plot was lightly verticut and spiked.
Current Status of the Study
The study was started on August 17, 2002 and was seeded on September 3, 2002. On May 7, 2003 all of the plots were sprayed with Roundup® to determine the actual population of RRCB plants in each plot. Subsequent Roundup® applications will be made to the entire study during the current growing season to remove any unwanted plant species.
This research project will conclude at the end of the 2003 growing season and the results will be placed in the 2004 Iowa State University Research Report.
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ISU Turfgrass:2003 Turfgrass Report | College of Agriculture |
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