1998 Iowa Turfgrass Research Report
1997 Preemergence Annual Grass Control Study
Barbara R. Bingaman, Nick E. Christians, and Michael B. Faust
The objective of this study was to evaluate the efficacy of Team Pro as a preemergent annual weed herbicide in turfgrass. This study was conducted at the Iowa State University Horticulture Research Station north of Ames, IA. The experimental plot was in 'Nassau' Kentucky bluegrass. The soil in this area was a Nicollet (fine-loamy, mixed, mesic Aquic Hapludoll) with 2.2% organic matter, a pH of 6.7, 3 ppm P, and 54 ppm K. Irrigation was used to supplement rainfall and maintain the turf in good growing condition.
The study design was a randomized complete block. Individual plot size was 5 x 5 ft with three replications and one row per replication. DowElanco furnished five herbicide + fertilizer granular formulations for this study. Team Pro 0.86GR (0.43% benefin and 0.43% trifluralin) + fertilizer (NAF-324), Team 0.87GR (0.58% benefin and 0.29% trifluralin) + fertilizer (NAF-323), and Pendimethalin 0.86GR + fertilizer were applied in single preemergence (PRE) applications at 2.0 lb a.i./A and in split PRE and postemergence (POST) applications at 1.5 lb a.i./A. Dimension 0.09GR + fertilizer was applied in a single PRE application at 0.38 lb a.i./A and Barricade 0.22GR + fertilizer was applied in a single PRE application at 0.50 lb a.i./A. There were a total of nine treatments including an untreated control (Table 1).
The herbicides were applied with 'shaker dispensers' to ensure uniform distribution. Following the PRE applications, the materials were 'watered in' with the irrigation system. The plot was mowed regularly at 2 inches.
Initial applications were made preemergently on May 7 before crabgrass germination. Crabgrass germination was detected in the untreated control plots on June 18. Sequential (postemergent) applications were made on June 2, eight weeks after the initial applications.
Phytotoxicity data were taken on May 12 and May 15. Phytotoxicity was assessed using a 9 to 1 scale: 9 = no damage and 1 = dead grass (Table 1). Visual quality data were taken on May 21, June 5, June 10, June 18, and June 25 (Table 2). Visual turf quality was evaluated with a 9 to 1 scale: 9 = best, 6 = lowest acceptable, and 1 = worst turf quality. Crabgrass control was determined by estimating percentage crabgrass cover per plot and subsequently calculating percent reduction as compared with the untreated controls. Percentage cover data were taken on July 2, July 10, July 15, July 30, and August 20 (Table 3). Percentage crabgrass reduction data were calculated for each of these collection dates (Table 4)
Data were analyzed with the Statistical Analysis System (SAS, version 6.10) using the Analysis of Variance (ANOVA) procedure. Means were compared with Fisher's Least Significant Difference (LSD) test.
There were no phytotoxicity symptoms on treated bluegrass (Table 1). The visual quality of all treated bluegrass was significantly better from May 21 through August 20. The quality of treated bluegrass was the same from June 10 through July 2. After the sequential applications, significant quality differences were evident among the treatments for July 10 and July 15 (Table 2).
The mean quality of all treated bluegrass was significantly better than the untreated control. The best mean quality was for bluegrass treated with Team Pro (NAF-324) at 1.50 lb a.i./A followed by 1.50 lb a.i./A, Team Pro (NAF-324) at 2.00 lb a.i./A, Team (NAF-323) at 1.50 lb a.i./A followed by 1.50 lb a.i./A, and Pendimethalin 0.86GR at 1.50 lb a.i./A followed by 1.50 lb a.i./A (Table 2).
All herbicides significantly reduced percentage crabgrass cover from July 2 through August 20 when compared with the untreated control (Table 3). The mean percentage cover of all treated bluegrass was significantly lower than the untreated control. All products except Pendimethalin 0.86GR at 2.00 lb a.i./A maintained crabgrass cover below 20% through August 20. Bluegrass treated with Team Pro (NAF-324) at 2.00 lb a.i./A, Team (NAF-323) at 2.00 lb a.i./A, Dimension 0.09GR at 0.38 lb a.i./, and Barricade 0.22 GR at 0.50 lb a.i./A had the least percentage crabgrass cover as compared to other treated and untreated turf.
There were significant reductions in crabgrass cover from July 2 through August 20 in all treated bluegrass when compared with the untreated control (Table 4). Bluegrass treated with Dimension 0.09GR at 0.38 lb a.i./A, Team Pro (NAF-324) at 2.00 lb a.i./A, Team (NAF-323) at 2.00 lb a.i./A, and Barricade 0.22GR at 0.50 lb a.i./A maintained at least 85% reduction in crabgrass cover throughout the duration of the study.
Table 1. Kentucky bluegrass phytotoxicity1 for the 1997 Preemergence Annual Grass Control Study.
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[preemergent] |
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[postemergent] |
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(lb a.i./A) |
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(lb a.i./A) |
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Untreated control |
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Team Pro 0.86GR + fertilizer NAF-324 |
1.5 |
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Team Pro 0.86GR + fertilizer NAF-324 |
2.0 |
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Team 0.87GR + fertilizer NAF-323 |
1.5 |
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Team 0.87GR + fertilizer NAF-323 |
2.0 |
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Pendimethalin 0.86GR + fertilizer |
1.5 |
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Pendimethalin 0.86GR + fertilizer |
2.0 |
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Dimension 0.09GR + fertilizer |
0.38 |
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Barricade 0.22GR + fertilizer |
0.50 |
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LSD0.05 |
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1Phytotoxicity was assessed using a 9 to 1 scale: 9 = no damage and 1 = dead turf.
Initial (preemergent) applications were made on May 7 and sequentials (postemergent) on July 2, 1997 (8 WAT).
NS = means are not significantly different at the 0.05 level.
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ISU Horticulture:Publications:1998 Turfgrass Report | College of Agriculture |