Nick E. Christians and Luke Dant
This study was conducted to evaluate the efficacy of several preemergence crabgrass herbicides. The research was completed at the Iowa State University Turfgrass Research Facility on 'Moonlight' Kentucky bluegrass. The designated plot area was seeded with crabgrass in April 2002 in order to make the trial as uniform as possible. 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.
The trial was conducted using a randomized complete block design. Each treatment was replicated three times with plots being 5 x 5 ft. The Scotts Company supplied treatments 2-8, treatments 9-11 were screened for Dow AgroSciences, treatments 12-17 for BASF and 18 and 19 for Syngenta. Treatment 1 was an untreated control. All liquid treatments 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. Granular materials were applied using 'shaker dispensers' in order to provide uniform application. All treatments were applied on April 22, 2002. The second application of treatment 9 was made on June 3.
Turf quality was taken on June 11 and 23 on a scale of 9-1 with 9 being excellent, 6 being lowest acceptable turf and 1 being the worst. Crabgrass cover was recorded on July 23 and again on August 23. This is reported as the percentage of the plot covered by crabgrass (0% = No crabgrass present and 100% = the plot was entirely 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.
There was no damage to the Kentucky bluegrass from any of the treatments during the study. The differences in quality recorded on May 11 and May 23 were due to differences in plant response to materials that contained nitrogen.
The crabgrass population was very high due to the sowing of crabgrass seed before treatments were applied. The control plots averaged 95% crabgrass cover at the August 23 rating date. Due to the very high crabgrass pressure, none of the treatments provided complete crabgrass control. The most effective materials were Dimension Ultra 40WP at 0.5 lbs ai/A, Barricade 65 WG at 0.5 lbs ai/A, and Barricade 4 FL at 0.65 lbs ai/A.
Table 1. Quality ratings and % crabgrass cover in the 2002 preemergence weed control study.
| Rate | Quality | % Crabgrass cover | |||||
|---|---|---|---|---|---|---|---|
| Trt. | Material | Active Ingredient | lb a.i./A | 5/11 | 5/23 | 7/23 | 8/23 |
| 1 | Untreated Control | N/A | NA | 5 | 4 | 88 | 95 |
| 2 | Scotts Turf Builder with Halts | Pendimethalin (1.29%) | 1.5 | 6 | 6 | 28 | 40 |
| 3 | Sta-Green Premium Crab-Ex | Dithiopyr (0.17%) | 0.252 | 6 | 7 | 43 | 57 |
| 4 | Vigoro Ultra Turf Crabgrass Preventer | Dithiopyr (0.17%) | 0.252 | 6 | 6 | 21 | 40 |
| 5 | Schultz Expert Gardener | Prodiamine (0.20%) | 0.314 | 7 | 7 | 50 | 77 |
| 6 | Sam's Choice Crabgrass Preventer | Prodiamine (0.28%) | 0.39 | 6 | 7 | 28 | 44 |
| 7 | Preen'n Green Lawns | Total a.i. =1.93%* | 3.03 | 6 | 6 | 31 | 53 |
| 8 | Lesco Dimension + Fertilizer | Dithioipyr (0.07%) | 0.128 | 6 | 6 | 28 | 67 |
| 9 | Dimension Ultra 40 WP (Split Applications) | Dithiopyr | 0.25 | 4 | 4 | 20 | 43 |
| 10 | Dimension Ultra 40 WP | Dithiopyr | 0.5 | 5 | 4 | 5 | 11 |
| 11 | Barricade 65 WG | Prodiamine | 0.5 | 4 | 4 | 13 | 32 |
| 12 | Pendulum 3.3 EC | Pendimethalin | 1.5 | 5 | 5 | 75 | 88 |
| 13 | Pendulum 3.3 EC | Pendimethalin | 2.0 | 5 | 4 | 72 | 92 |
| 14 | Pendulum 3.8 CS | Pendimethalin | 1.5 | 5 | 4 | 53 | 83 |
| 15 | Pendulum 3.8 CS | Pendimethalin | 2.0 | 5 | 5 | 65 | 78 |
| 16 | Pendulum 2 G | Pendimethalin | 1.5 | 5 | 4 | 43 | 62 |
| 17 | Pendulum 2 G | Pendimethalin | 2.0 | 5 | 4 | 22 | 23 |
| 18 | Barricade 4 FL | Prodiamine | 0.5 | 5 | 4 | 33 | 57 |
| 19 | Barricade 4 FL | Prodiamine | 0.65 | 6 | 5 | 5 | 14 |
| 20 | Untreated Control | N/A | NA | 5 | 4 | 93 | 94 |
| LSD 0.05 | .94 | .94 | 25 | 33 | |||
*Active ingredients include: Benefin (0.82%), Trifluralin (0.43%), Triclopyr (0.5%), Clopyralid (0.18%)
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ISU Turfgrass:2003 Turfgrass Report | College of Agriculture |
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