Nick Christians and Luke Dant
The purpose of this study is to evaluate the effectiveness of varying rates of Velocity (bispyrobac-sodium) herbicide. The study is being conducted at Veenker Memorial Golf Course on 'Cato' creeping bentgrass maintained at fairway height.
All plots in the trial were 5 ft by 5 ft and organized in a randomized complete block design. The initial treatments of Velocity herbicide were made on August 1, 2002. They were applied using a carbon dioxide backpack sprayer with #8002 flat fan TeeJet nozzles at 30-40 psi and diluted to a total spray volume of 3 gal per 1000 sq. ft. For the treatments of Velocity herbicide requiring split applications, the second treatment was made on August 14. Prograss was applied per label instructions at a rate of 0.75 lb per acre. Prograss was applied on October 8 and again on October 30.
The phytotoxic effects of Velocity were recorded two weeks after each herbicide application. A scale from 1 to 9 with 1 being complete turfgrass death and 9 being no damage was used. Beginning September 5, turfgrass quality was observed to track the recovery of damaged turf. Turfgrass quality was rated on a scale of 9-1 with 9 being excellent, 6 being acceptable and , 1 being the worst. On May 20, 2003 when Poa annua was most visible, the percentage of Poa annua covering each plot was recorded.
Data were analyzed using Statistical Analysis System and the Analysis of Variance procedure. Treatments effects were tested using Fisher's Significant Difference (LSD) test.
Table 1.
| Rate | Rate | Turfgrass Phytotoxicity | Turf Quality | % Poa Annua Coverage | ||||||||
|---|---|---|---|---|---|---|---|---|---|---|---|---|
| Trt | Material | g a.i./A | lb a/i. A | 8/6/02 | 8/14/02 | 8/22/02 | 8/29/02 | 9/5/02 | 9/20/02 | 10/4/02 | 10/25/02 | 5/20/03 |
| 1 | Untreated Control | N/A | N/A | 9 | 9 | 8 | 9 | 9 | 9 | 9 | 9 | 23 |
| 2 | Velocity 80WP | 30 | 0.066 | 6 | 8 | 7 | 7 | 9 | 9 | 9 | 9 | 20 |
| 3 | Velocity 80WP (Split Application) | 30 | 0.066 | 6 | 7 | 8 | 7 | 8 | 8 | 9 | 9 | 15 |
| 4 | Velocity 80WP | 45 | 0.099 | 6 | 7 | 9 | 9 | 9 | 9 | 9 | 9 | 17 |
| 5 | Velocity 80WP (Split Application) | 45 | 0.099 | 6 | 6 | 6 | 5 | 5 | 6 | 7 | 9 | 17 |
| 6 | Velocity 80WP | 60 | 0.132 | 6 | 6 | 8 | 8 | 9 | 9 | 9 | 9 | 15 |
| 7 | Velocity 80WP (Split Application) | 60 | 0.132 | 6 | 6 | 4 | 3 | 4 | 5 | 7 | 8 | 20 |
| 8 | Velocity 80WP | 90 | 0.198 | 6 | 4 | 8 | 8 | 8 | 9 | 9 | 9 | 17 |
| 9 | Prograss 1.5EC | N/A | 0.75 | 9 | 9 | 9 | 8 | 9 | 9 | 9 | 9 | 1 |
| LSD | 0 | 1.2 | 2.0 | 2.5 | 0.83 | 0.57 | 0.63 | NS | 9.25 | |||
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ISU Turfgrass:2003 Turfgrass Report | College of Agriculture |
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