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January 6, 2011

The information below is a report on a Corsair Herbicide trial conducted by undergraduate student Shawn Fopma at Wakonda golf club in Des Moines during the 2010 season. It was part of a Horticulture 490 special studies course.

Corsair Herbicide Treatment
Shawn Fopma
Iowa State University

In 2008, a major re-grassing project took place on greens, fairways, bluegrass green surrounds and first cut of rough at Wakonda Club. Two years later, unsightly perennial ryegrass plants had begun to germinate throughout the newly seeded Pennlinks II/Penneagle II creeping bentgrass fairways. Due to the contrasting colors of bentgrass and ryegrass, a test plot was set up to test the effectiveness and efficiency of Corsair herbicide. Corsair is a selective herbicide, which controls tall fescue, ryegrass, and many broadleaf weeds in turfgrass. Corsair selective herbicide is a dispersible granule that, when mixed with water, can be applied as a spot or broadcast spray treatment. Also, Corsair is a very active compound at low rates, which needs adequate moisture by rainfall or irrigation to activate the herbicide.

For our test, a 6,000 ft2 test plot was set up on the 11th fairway, as well as, a 4,000 ft2 test plot on the fairway nursery. A 4’ x 8’ sheet of plywood was laid on each test plot to cover a section of grass, which we used as a control.

For the first test, a tank mix consisting of 0.18oz of Corsair, 0.4oz of buffer and 20 gallons of water was produced. A buffer product was added due to the high alkaline-levels in the water. Then, the Corsair was applied at an extremely low rate of 0.009oz/1000 ft2. Our plan was to start with a low rate and make multiple applications at this rate. The goal of this application was to see Corsair’s effectiveness at a low rate with multiple applications.

Approximately two weeks following the first application, another Corsair application was applied to the test plots at the same low-rate. That same day, another test plot similar to the first two was created to test Corsair at a higher rate. During this test, Corsair was applied at 0.03oz/1000 ft2. According to the label, this application would be considered a low-medium rate. The goal of this application was to see how the surrounding bentgrass reacted to a higher rate of Corsair.


Overall, the Corsair tests proved effective; notable reduction of ryegrass was seen in all plots, especially the test plot in which Corsair was applied at a higher rate. Little to no chlorotic effects were observed on bentgrass test plots. The only problematic area observed was an area in which cart traffic was heavy on multiple days of significant heat and humidity. Due to this past summer’s high disease pressure and negative weather conditions, turf conditions became undesirable so the program was not continued; however, it is expected to continue in 2011.