Nick E. Christians and Luke Dant
This study was conducted in order to evaluate the effectiveness of and turf safety of Acclaim herbicide. The study was conducted at the Iowa State University Turfgrass Research Facility on 'Moonlight' Kentucky bluegrass. In order to maximize crabgrass germination, the plot area was overseeded with crabgrass in April 2002.
All treatments were replicated three times and the experimental design was a randomized complete block. Individual plots were 5 ft by 5 ft in size. All treatments were diluted to a total spray volume 3 gal per 1000 sq ft and applied using a carbon dioxide backpack sprayer with #8002 flat fan TeeJet nozzles at 30-40 psi. All treatments were applied on June 15. The soil on the area is a Nicollett (fine-loamy, mixed, mesic Aquic Hapludoll) with 3.0 % organic matter, 22 ppm P, 71 ppm K, and a pH of 7.95.
Turfgrass phytotoxicity was reported on June 20, June 26 and again on July 22 using a scale of 1-9 (1 = significant visual damage and 9 = no visual damage). In addition, crabgrass phytotoxicity was recorded on June 20 and 26 using the same scale as previously mentioned. On July 23 and again on August 23 crabgrass cover was estimated on a percentage of the plot covered by crabgrass with 0% being no crabgrass present and 100% being completely covered with crabgrass.
Data were analyzed using Statistical Analysis System (SAS) software and the Analysis of Variance procedure. Treatment effects were tested using the Least Significant Difference (LSD) test.
No damage was observed on the Kentucky bluegrass on June 20 or 26, but by July 22 each of the 3 Acclaim EW treatments were observed to discolor the bluegrass. All treatments significantly damaged crabgrass compared to the control on June 26. The Drive 75 DF caused the most visual damage to the crabgrass. All treatments significantly reduced crabgrass populations on July 23 and August 23, although there had been considerable recovery of crabgrass populations by August 23. While there were no statistically significant differences among treatments in crabgrass control, the Drive 75 DF at 0.75 lbs ai/A provided the greatest numeric reduction in crabgrass populations compared to the other treatments.
Table 1. Postemergence crabgrass control study 2002.
| Rate | Rate | Turfgrass Phytotoxicity | Crabgrass Phytotoxicity | % Crabgrass Cover | ||||||
|---|---|---|---|---|---|---|---|---|---|---|
| Material | lb a.i./A | Product/A | 6/20 | 6/26 | 7/22 | 6/20 | 6/26 | 7/23 | 8/23 | |
| 1 | Untreated control | N/A | NA | 9 | 9 | 9 | 9 | 9 | 83 | 88 |
| 2 | Acclaim EW | 0.089 | 20 oz | 9 | 9 | 5 | 8 | 5 | 33 | 60 |
| 3 | Acclaim EW | 0.124 | 28 oz | 9 | 9 | 4 | 7 | 4 | 19 | 55 |
| 4 | Acclaim EW | 0.174 | 39 oz | 9 | 9 | 3 | 4 | 2 | 16 | 50 |
| 5 | Drive 75DF | 0.75 | 1 lb | 9 | 9 | 8 | 3 | 1 | 9 | 36 |
| LSD 0.05 | NS | NS | 1.2 | 1.3 | 1.8 | 22 | 25 | |||
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ISU Turfgrass:2003 Turfgrass Report | College of Agriculture |
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