1998 Iowa Turfgrass Research Report
1997 Non-selective Herbicide Study
Barbara R. Bingaman, Nick E. Christians, and Michael B. Faust
The objective of this study was to demonstrate trim and edging of cool season turfgrasses with non-selective herbicides. This study was designed as a demonstration plot for the 1997 Iowa State University Turfgrass Field Day on August 14 at the Horticulture Research Station north of Ames, IA. The plot was in an area of 'common' Kentucky bluegrass adjacent to an ornamental grass bed.
The study was designed with the treated plots in a single row. Each plot was a 0.5 x 8.0 ft. (4 ft2) strip with 0.5 x 1.0 ft. barrier strips between plots. This study was not replicated and the treatments were applied once. There were seven treatments including an untreated control (Table 1). Reward was applied alone at 2.0 pt. product/A and at 0.5, 1.0 and 1.5 pt. product/A in combination with Roundup Pro at 2 qt. product/A. Fusilade II at 4, 8, and 16 oz. product/A was combined with Reward at 1.0 pt. product/A. LESCO spreader/sticker was added to all treatments at 0.25% V/V.
The herbicides were mixed in 60 ml of water and applied at 30 psi using a CO2 backpack sprayer equipped with one TeeJet™ #8006 flat fan nozzle. Applications were made to ensure that there was no herbicide drift. Water was withheld from the plot for at least 24 hours post-treatment.
Plots were rated for plant damage using a 9 to 1 scale: 9 = 100% brown, 5 = 35-50% brown, and 1 = 100% green. Ratings were taken on August 1, August 4, August 6, August 14, August 21, August 28, September 5, September 12, September 18, and September 26 (Table 1). The percentage of damaged and dead plants per plot was also recorded on these dates. These data were recorded as the percent brown area per plot (Table 2). In addition, notes on species affected, species regrowth, and spreading of the herbicide affected areas were made on each collection day.
On August 1, broadleaf plants were slightly discolored (bleached) in turf treated with Reward alone at 2.0 pt. product/A and at 0.5 and 1.0 pt product/A in combination with Roundup Pro (Table 1). There was no discoloration of any treated turfgrass.
Turfgrass and broadleaves were damaged and turning brown in all treated plots by August 4. There were a few redroot pigweed plants treated with Reward at 1.0 pt product/A plus Fusilade II at 16 oz. product/A that were undamaged. There was still 25 - 40% green cover in plots treated with Reward alone, Reward at 0.5 pt. plus Roundup Pro at 2 qt. product/A, and Reward at 1.0 pt. product/A plus Fusilade II at 4 oz. product/A. In the other treated plots, 80 - 90% of the grass was brown (Table 2).
On August 6, 40% of the cover was still green within the plot treated with Reward at 0.5 pt. product/A plus Roundup Pro at 2 qt. product/A and 30% of the cover was green in the plot treated with Reward at 1.0 pt. product/A plus Fusilade II at 4 oz product/A. In other treated plots there was ¾ 20% green cover.
By August 14, in those plots treated with Reward + Roundup Pro the herbicide affected area had begun to widen. There was „ 70% dead plants in all treated plots. In addition, there was 100% brown cover in plots treated with Reward at 1.0 and 1.5 pt. product/A plus Roundup Pro at 2 qt. product/A.
On August 21, all herbicides had produced at least 80% brown plants except Reward alone at 2.0 pt. product/A. The pigweeds treated with Reward at 1.0 pt. product/A plus Fusilade II at 16 oz. product/A were still undamaged.
By August 28, the grass had begun to spread back into some of the treated plots. The plot treated with Reward at 2.0 pt. product/A was 50% overgrown with grass and the Reward + Fusilade II plots were beginning to fill in with grass. The plots treated with Reward at 0.5, 1.0, and 1.5 pt. product/A plus Roundup Pro at 2.0 qt. product/A were completely brown.
By September 5 (5 WAT), there was 75% green cover in the plot treated with Reward at 1.0 pt. product/A plus Fusilade II at 4 oz. product/A. Regrowth of 50% was recorded in plots treated with either Reward at 20 pt. product/A or Reward at 1.0 pt. product/A plus Fusilade II at 8.0 oz. product/A. There was < 5% grass regrowth in plots receiving Reward at 0.5, 1.0, and 1.5 pt. product/A plus Roundup Pro at 2 qt. product/A.
The turf plots treated with Reward at 0.5, 1.0, and 1.5 pt. product/A plus Roundup Pro at 2 qt. product/A still had very little regrowth on September 12 (6 WAT). There was 90% regrowth in the plot treated with Reward at 1.0 pt. product/A plus Fusilade II at 4 oz. product/A.
Table 1. Damage ratings1 for grass and broadleaf species in Kentucky bluegrass treated for the 1997 Nonselective Herbicide Study.
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1 |
Reward |
2.0 pt |
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2 |
Reward + Roundup Pro |
0.5 pt |
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3 |
Reward + Roundup Pro |
1.0 pt |
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4 |
Reward + Roundup Pro |
1.5 pt |
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5 |
Reward + Fusilade II |
1.0 pt |
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6 |
Reward + Fusilade II |
1.0 pt |
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7 |
Reward + Fusilade II |
1.0 pt |
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LESCO Spreader/Sticker was added to all treatments at 0.25% v/v = 0.15 ml/plot.
1Damage was assessed using a 9 to 1 scale: 9 = 100% brown, 5 = 50% brown and 1 = 100% green.
Table 2. Percentage brown plant cover per plot1 in Kentucky bluegrass treated for the 1997 Nonselective Herbicide Study.
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------------------------------------------- % ----------------------------------------- |
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1 |
Reward |
2.0 pt |
5 |
75 |
80 |
80 |
60 |
50 |
50 |
40 |
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2 |
Reward + Roundup Pro |
0.5 pt |
5 |
60 |
60 |
75 |
90 |
100 |
95 |
90 |
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3 |
Reward + Roundup Pro |
1.0 pt |
5 |
80 |
90 |
100 |
100 |
100 |
95 |
95 |
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4 |
Reward + Roundup Pro |
1.5 pt |
0 |
90 |
90 |
100 |
100 |
100 |
100 |
95 |
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5 |
Reward + Fusilade II |
1.0 pt |
0 |
70 |
70 |
70 |
80 |
70 |
25 |
10 |
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6 |
Reward + Fusilade II |
1.0 pt |
0 |
90 |
80 |
85 |
90 |
90 |
50 |
30 |
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7 |
Reward + Fusilade II |
1.0 pt |
0 |
90 |
80 |
85 |
95 |
95 |
90 |
80 |
LESCO Spreader/Sticker was added to all treatments at 0.25% v/v = 0.15 ml/plot.
1Percentage brown cover
represents the area covered by brown damaged and dead plants
per plot.
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ISU Horticulture:Publications:1998 Turfgrass Report | College of Agriculture |