Nick E. Christians and Luke Dant
The purpose of this study was to evaluate weed control and turf phytotoxicity of Scotts Weed-B-Gone and other competitive broadleaf herbicide formulations. The research was conducted at the Iowa State University Turfgrass Research Facility on 'Parade' Kentucky bluegrass.
The trial was arranged as a randomized complete block. Each treatment was replicated three times with plots being 5 ft x 5 ft. All products were supplied by Scotts Company. Non-Scotts products were applied at label rates. All treatments were applied using a carbon dioxide backpack sprayer with #8002 flat fan nozzles at 30-40 psi and diluted to a total spray volume of 3 gal per 1000 sq. ft. The herbicide application was made on May 14, 2002. The soil on the area is a Nicollett (fine-loamy, mixed, mesic Aquic Hapludoll) with 4.9 % organic matter, 6 ppm P, 171 ppm K, and a pH of 7.05.
Ratings of damage to dandelions were made at 1 and 3 days after application and at 1 and 3 weeks after application with a percentage scale ranging from 0 to 100. On June 4, five weeks after application, a percentage of dandelion coverage was taken. Turfgrass phytotoxicity was monitored at one and three weeks after application on a scale ranging from 9-1, with 9 being no damage and 1 being complete turf death.
Data were analyzed using Statistical Analysis System (SAS) and the Analysis of Variance procedure. Treatment effects were tested using Least Significant Difference (LSD) test.
No damage was observed on the Kentucky bluegrass turf at any time during the study (Table 1). All materials caused significant damage to weeds at 1 day after treatment. By the second day, the Trimec + Sulfentrazone was showing the most damage on weeds, followed by the Spectracide Weed Stop. All materials provided significant reduction in dandelion cover compared to the control. However, none of the treatments provided 100% control. There were no significant differences among the herbicide treatments in dandelion control, although WBG S-10304 provided the greatest numerical reduction.
Table 1. Postemergence control of dandelion by various broadleaf weed herbicides in 2002.
| Rate | Dandelion Phytotoxicity | % Dandelion Cover | Turf Phytotoxicity | |||||
|---|---|---|---|---|---|---|---|---|
| Material | Product/A (ounces) | 5/15 | 5/17 | 5/21 | 6/04 | 6/18 | 5/21 | 6/4 |
| Untreated Control | NA | 0 | 0 | 0 | 0 | 57 | 9 | 9 |
| Trimec + Sulfentrazone | 65.34 | 12 | 30 | 33 | 37 | 8 | 9 | 9 |
| S-10448 (Horsepower Conc.) | 141.57 | 12 | 23 | 23 | 22 | 9 | 9 | 9 |
| WBG FA Conc. S-10300 | 217.8 | 8 | 22 | 22 | 18 | 7 | 9 | 9 |
| WBG FA Conc. S-10301 | 217.8 | 10 | 17 | 25 | 23 | 6 | 9 | 9 |
| WBG S-10304 | 217.8 | 10 | 18 | 23 | 32 | 4 | 9 | 9 |
| WBG Weed Killer Conc. | 217.8 | 12 | 15 | 23 | 15 | 5 | 9 | 9 |
| Spectracide Weed Stop Weed Killer Conc. | 174.24 | 15 | 28 | 33 | 33 | 5 | 9 | 9 |
| Bayer All-In-One Weed Killer Conc. | 217.8 | 8 | 20 | 27 | 30 | 10 | 9 | 9 |
| LSD 0.05 | 7 | 6 | 8 | NS | 9 | NS | NS | |
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ISU Turfgrass:2003 Turfgrass Report | College of Agriculture |
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