Introduction
This study was conducted on a mature stand of creeping bentgrass (Agrostis stolonifera) and Poa annua at the Valentine Turfgrass Research Center, Penn State University, University Park, PA. The objective of the study was to determine the efficacy of plant growth regulators and bio-stimulants by color ratings and determinations of plant height and foliar yield.

Methods and Materials

This study was a randomized complete block design with three replications. All treatments were applied on June 5, June 19, July 2, July 16, July 31, 2002 using a three foot CO2 powered boom sprayer calibrated to deliver 40 gpa using two, flat fan, 11004 nozzles at 40 psi. The test site was maintained
similar to that of a golf course putting green with respect to irrigation, fertilization and mowing. Turfgrass height was measured using a Turfcheck 1 prism. After the June 5 application date Coron was substituted for ammonium sulfate as a nitrogen source.
A soil test was conducted on the test site on April 10, 2002 by the Agricultural Analytical Services Laboratory, Penn State University, University Park PA. The soil test revealed a soil pH of 6.1, phosphorus concentration of 61 ppm, and potassium concentration of 115 ppm. The soil test report recommended the site receive 2 lb K2O/M for optimum growing conditions. Therefore, 1 lb K2O/M was applied to the site on April 24 and May 7, 2002 from an 0-0-60 basic fertilizer using a three foot drop spreader. On May 7, 2002 1 lb P2O5/M was applied using a three foot drop spreader from a 0-46-0 basic
fertilizer.
On April 10, 2002 1.5 lbs N/M was applied to the test site using a three foot drop spreader. The nitrogen source was IBDU 31-0-0 (Par Ex IBDU greens grade) with an analysis of 27% water insoluble nitrogen and 4% urea nitrogen.
The soil of the test site was also evaluated for particle size using the pipette method. The test revealed this particle size percent by weight; gravel (>2mm) 1.6, very coarse sand (2 - 1mm) 3.6, coarse sand (1 - 0.5mm) 25.1, medium sand (0.5 - 0.25mm) 33.3, fine sand (0.25 - 0.15mm) 12.4, very fine sand
(0.15 - 0.05mm) 3.8, silt (0.05 – 0.002mm) 14.7, and clay (< 0.002mm) 5.7.
A tank mix of Bravo Ultrex (2.6 oz/M), Chipco GT (2oz/M), and Bayleton 50 (0.11 oz/M) was applied on June 4, 2002 as dollar spot had been identified on the test site. On June 19, 2002 Cleary’s 3336 (3 oz/M) and Fungo (2 oz/M) were tank mixed and applied to the test site to control dollar spot again. In order to control cutworms found in the test site, Scimitar was applied on June 20, 2002 at a rate of 10 oz/A. Dollar spot was again identified and Banner Maxx (2 oz/M) was applied to the test site on July 2, 2002.

Two preventive fungicide applications of a tank mix of Bravo Ultrex (2.6 oz/M), Chipco GT (2oz/M), and Bayleton 50 (0.11 oz/M) were applied to the test site on July 21 and Aug 6, 2002. On Aug 5, 2002 Scimitar (10 oz/A) was applied to control cut worms that had been identified on the test site. All applications were made with a Toro Multi Pro 5500 with 11, ¼ TT J10-VS flood jet nozzles spaced at 20 inches and calibrated to deliver two gpm.

Results and Discussion

At no time did color ratings reveal that treated turf was in an unacceptable condition (Table 1). However, on June 10, turf treated with Primo Maxx, Kick, Potent-Sea, N-Hance, Base One, and Coron tended to have poorer color than untreated turf. Throughout the course of the study, there was a consistent tendency for turf that was treated with all materials to have color better than the untreated control.
On some dates, significant differences were found for height measurements (Table 2). For example, on June 10, turf treated with Primo Maxx, Astron, and Coron; Primo Maxx, Kick, Potent-Sea, N-Hance, Base One, and Coron; Primo Maxx, MacroSorb Foliar, and Coron; Primo Maxx and Coron; Primo Maxx and Gary’s Green 18-3-4; and Primo Maxx, Gary’s Green 18-3-4, and Gary’s Green PK Plus 3-21-18 had lower height than untreated turf. However, by June 24 turf treated with Primo Maxx, Kick, Potent-Sea, N-Hance, Base One and Coron was found to have a height higher than untreated turf.
On July 8, turf treated with Primo Maxx was shorter than untreated turf and turf that had received Coron and Gary’s Green 18-3-4 with Primo Maxx. On July 16, only turf treated with Primo Maxx was shorter than the untreated turf. The other two dates on which a treated turf was found to have a height difference from the untreated turf was on August 12. On this date, turf treated with Primo Maxx plus Coron was shorter than the untreated turf. However, on August 19 the reverse response was found.
With exception of turf treated with Coron or that treated with Primo Maxx and Gary’s Green 18-3-4, all other treated turf had lower clipping yields than untreated turf on June 10, 17, and 24 (Table 3). By July 1, only turf treated with Primo Maxx; Primo Maxx, Astron and Coron; Primo Maxx and Coron; and Primo Maxx, Gary’s Green 18-3-4 plus Gary’s PK Plus 3-21-18 had lower clipping yields. On July 8, only turf treated with Coron alone and that treated with Primo Maxx, Kick, Potent-Sea, N-Hance, Base One and Coron had clipping yields similar to the untreated check, all other treatments caused significantly lower clipping yields. On July 16, no treatments caused significantly lower yields than untreated turf, however, turf treated wit Primo Maxx alone had less yield than turf treated with Coron alone. On July 22, only turf treated with Coron alone and Primo Maxx with Gary’s Green 18-3-4 plus Gary’s PK Plus 3-21-8 had yields similar to the untreated turf, all other treated turf had lower yields than the untreated turf. On Aug 5, turf treated with Primo Maxx had less clipping yield than the untreated turf. In addition, turf treated with Primo Maxx, produced less yield than turf treated with Primo Maxx, Astron, and Coron; Primo Maxx, Kick, Potent-Sea, N-Hance, Base One, and Coron; Primo Maxx, MacroSorb Foliar, and Coron; and Coron alone. On August 12, only turf treated with Primo Maxx had less yield than untreated turf. By August 19, turf treated with Primo Maxx, Kick, Potent-Sea, N-Hance, Base One, and Coron; Primo Maxx, MacroSorb Foliar, and Coron; Primo Maxx plus Coron; and Primo Maxx, Gary’s Green 18-3-4, and Gary’s Green PK Plus 3-21-18, had yields that were significantly higher than untreated turf.
For the first application of treatments (applied on June 5), ammonium sulfate 21-0-0 was used at a rate of 0.125 lb N/M as a nitrogen source. On June 6, severe discoloration was observed (Table 4). Therefore, Coron was used as the nitrogen source for the remainder of the study.

Table 1. Color ratings on a scale of 0-10 where 0 = brown, 7= acceptable, and 10 = dark green of PGR’s applied to creeping bentgrass taken in 2002.

Table 1 (Continued). Color ratings on a scale of 0-10 where 0 = brown, 7=acceptable, and 10 = dark green of PGR’s applied to creeping bentgrass taken in 2002.

Table 1 (Continued). Color ratings on a scale of 0-10 where 0 = brown, 7=acceptable, and 10 = dark green of PGR’s applied to creeping bentgrass taken in 2002.

Table 2. Height ratings (in inches) of PGR’s applied to creeping bentgrass taken in 2002.

Table 2 (Continued). Height ratings (in inches) of PGR’s applied to creeping bentgrass taken in 2002.

Table 2 (Continued). Height ratings (in inches) of PGR’s applied to creeping bentgrass taken in 2002.

Table 3. Fresh clipping weight ratings (in grams) of PGR’s applied to creeping bentgrass taken in 2002.

Table 3 (Continued). Fresh clipping weight ratings (in grams) of PGR’s applied to creeping bentgrass taken in 2002.

Table 3 (Continued). Fresh clipping weight ratings (in grams) of PGR’s applied to creeping bentgrass taken in 2002.

Table 4. Discoloration ratings on a scale of 0-10 where 0 = worst, 7= acceptable, and 10 = best of PGR’s applied to creeping bentgrass taken in 2002.