1998 Iowa Turfgrass Research Report
Effect of Primo on Kentucky Bluegrass Sod Establishment
Barbara R. Bingaman, Nick E. Christians, and Michael B. Faust
The objective of this study was to determine the impact of the growth regulator, Trinexapac-ethyl (Primo), on the establishment of 'Majestic' Kentucky bluegrass sod. This study was conducted at the Iowa State University Horticulture Research Station north of Ames, Iowa. The soil in this area was a Nicollet (fine-loamy, mixed, mesic Aquic Hapludoll) with 4.0% organic matter, a pH of 7.30, 2 ppm P, and 79 ppm K. This study was a repeat of a 1996 study. Rainfall was sporadic throughout the duration of this study. Supplemental irrigation was used to maintain the bluegrass in good growing condition and to facilitate sod root development
The study was designed as a randomized complete block with four replications. Individual plots were 5 x 5 ft. Primo 1EC was applied at three treatment regimes. All Primo 1EC applications were made at 0.75 fl oz/1000 ft2, the label rate for Kentucky bluegrass. The four treatments included an untreated control, applications of Primo 1EC two weeks prior to sod harvest, two weeks after sod establishment, and a combination treatment of two weeks prior plus two weeks after establishment (Table 1). Primo 1EC was applied at 30 psi with a CO2 powered backpack sprayer equipped with TeeJet™ #8006 flat fan nozzles. The Primo was mixed in 283 ml of water which translates to an application rate of 3 gal/1000 ft2. The two weeks before sod cutting treatments were made on June 11. The two weeks after sod cutting treatments were applied on July 10.
The bluegrass on the entire experimental plot was cut on June 26 using an 18-inch sod cutter. Within each individual plot, sod pieces were cut that matched the outside diameter of 12 x 12 in. wooden frames with 18 mesh bottom screens. The pieces were trimmed and transplanted into the frames. The frames with the sod pieces were returned to the holes and placed flush with the soil surface. There were four frames per individual plot, one in each of four quadrants.
The study was watered thoroughly upon completion and was watered on a regular basis to prevent the sod from drying. One frame per plot was sampled on each of four collection dates beginning July 10, two weeks after establishment. The other frames were harvested at two week intervals on July 21, August 6, and August 20 (Table 1).
Root development was measured using a hydraulic sod pulling apparatus equipped with steel cables that could be attached to screw hooks on the corners of wooden frames (Figure 1). The tensile strength required to 'pull' a frame from the soil was measured in pounds per square inch (psi).
Visual quality data were taken on June 18, June 25, July 2, July 9, July 15, July 21, July 30, August 6, and August 20 (Table 2). Visual quality was assessed using a 9 to 1 scale: 9 = best, 6 = lowest acceptable, and 1 = worst quality.
Data were analyzed using the Statistical Analysis System (SAS, Version 6.10) and the Analysis of Variance (ANOVA) procedure. Means were compared with Fisher's Least Significant Difference (LSD) test.
There were no differences in turf quality between the treated and untreated plots (Table 2). No bluegrass phytotoxicity was detected during the study. There were no tensile strength differences in sod harvested on either July 10, July 21, or August 6 (Table 1). On August 20, the sod treated with Primo 1EC two weeks before cutting had significantly more root development than sod receiving the other Primo treatment regimes and the untreated control.
Table 1. Root tensile strength and knitting of Kentucky bluegrass sod growing in frames in the 1997 sod production study measured by the number of pounds per square inch (PSI) required to pull 1 ft2 frames.
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1 |
Untreated control |
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2 |
Primo 1EC |
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3 |
Primo 1EC |
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4 |
Primo 1EC |
0.75 |
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LSD0.05 |
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Two weeks prior to cutting sod treatments were applied on June 11. Sod was cut and put into frames on June 26. Two weeks after sod establishment treatments were made on July 10. Sod frames were pulled on July 10, July 22, August 6, and August 20.
NS = means are not significantly different at the 0.05 level.
Table 2. Visual quality1 of Kentucky bluegrass sod growing in frames in the 1997 sod production study.
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1 |
Untreated control |
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2 |
Primo 1EC |
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3 |
Primo 1EC |
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4 |
Primo 1EC |
0.75 |
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LSD0.05 |
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Two weeks prior to cutting sod treatments were applied on June 11. Sod was cut and put into frames on June 26. Two weeks after sod establishment treatments were made on July 10.
1Visual quality was assessed using a 9 to 1 scale: 9 = best, 6 = lowest acceptable, and 1 = worst quality.
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ISU Horticulture:Publications:1998 Turfgrass Report | College of Agriculture |