Rye
Objective: Field evaluation of phosphite-based products challenged with heat stress and Pythium.
Conclusions: This site was an in-play golf course fairway consisting of perennial
ryegrass. There were virtually no differences in turf color or density. Reduction in turf quality was due primarily to injury caused by Pythium blight. Pythium blight began to develop at the test site around mid July and became severe in early to mid August.
Significant disease pressure was observed on August 1 and August 12.
GRIGG BROS: All treatments containing Grigg Bros products provided excellent control of Pythium blight. Means of individual treatments were not statistically separated. Graph (PO3-3rye-05_griggpythium) shows the mean percent disease of plots treated with either Grigg Bros products or fertilizer alone.
Bentgrass
Objective: Evaluate overall performance of phosphite-based products challenged with heat stress and Pythium.
Conclusions: In this trial, there was little separation of means of all rating dates and data types. Plots were visually rated for quality, color, turf density, percent disease on June 4, June 14, June 29, July 18, July 29, and August 5. Algae cover was also visually estimated on July 18, July 29, and August 5. Tissue samples were collected and analyzed for superoxide dismutase (SOD), a ubiquitous antioxidant enzyme that serves as the first line of defense against superoxide and single oxygen radicals, on July 24 and September 9. Photochemical efficiency was measured using on Opti-Science GFP-Meter on
July 6 and September 9.
There was no significant Pythium blight pressure at any rating date throughout the season.
Several attempts were made to inoculate the plots with active isolates of Pythium spp., however, disease did not develop.
GRIGG BROS: Due to high variation within replications, there was little statistical separation in most ratings. There were some consistent numerical trends, however.
The general trend was that treatment with Grigg Bros products resulted in higher turf quality than those treated with soluble fertilizer alone. Though there was little separation statistically, turf quality increased from 5.45 when only fertilized to 6.5 or higher on July 18 when treated with a Grigg Bros product. At most ratings, Grigg Experimental #1 at 6 fl oz/1000ft2 and PK Plus alone performed at or near the top. With the exception of the July 18 rating date, Grigg Experimental #2 did not noticeably increase the quality. Color was not significantly impacted at any rating date with any Grigg Bros product. Turf density was also not significantly impacted, with the exception of Grigg Experimental #1 at 6 fl oz/1000ft2 on August 5, when density averaged 7.13 as
opposed to 5.7 in the plots receiving fertilizer alone.
There was no significant Pythium pressure in this trial.
Algae was rated on July 18, July 29, and August 5. There was no statistical separation due to high variability in the first two ratings. However, there were very noticable differences in some plots. In plots treated with either PK Plus or Grigg Experimental #1 at 6 fl oz/1000ft2, there was virtually no algae. Algae cover averaged 11, 7, and 9.5% in fertilized plots alone, while only 0, 0, 0.8% of plots treated with Grigg Experimental #1 at 6 fl oz/1000ft2 were covered with algae at each rating date, respectively.
In this trial, PK Plus or Grigg Experimental #1 at 6 fl oz/1000ft2 performed better than other products. PK Plus alone outperformed PK Plus tank mixed with Gary's Green Ultra on turf quality, density, and algae suppression. Grigg Experimental #1 did not perform as consistantly at 4 fl oz/1000ft2 as it did when applied at 6 fl oz/1000ft2. Grigg Experimental #2 did not perform as well as Experimental #1 or PK Plus.
