PROGRESS REPORT (June 3, 2016)

Transcription

1 GEORGIA GOLF ENVIRONMENTAL FOUNDATION PROGRESS REPORT (June 3, 2016) TEMPORAL, CULTURAL, BIOLOGICAL, AND CHEMICAL PRACTICES TO ENHANCE SPRING DEAD SPOT (SDS) CONTROL OF BERMUDAGRASS IN GEORGIA Principal Investigator: Dr. Alfredo Martinez Project Coordinator: Mr. Brian Vermeer Address: Department of Plant Pathology, Griffin Campus, 1109 Experiment Street, The University of Georgia. Griffin, GA Telephone: (706) Fax: (706) COMBINATION OF TEMPORAL, CULTURAL, AND CHEMICAL PRACTICES FOR THE CONTROL OF SPRING DEAD SPOT AND EVALUATION OF NEW CHEMISTRIES PROGRESS: Introduction In experimental design and data collection has been consistent with previously described protocols. We continue using the SDS trials selected at the onset of this grant. One site is located at a bermudagrass 419 rough area on the 10 th hole and on the fairway of 17 th hole at Towne Lake Hills Golf Club in Woodstock GA (Figure 1). A second trial is located at the University of Georgia- Griffin campus on TifSport bermudagrass sward with SDS history (Figure 1). Materials and Methods Fall 2015: As per the original protocol, the areas were either core-aerated or not core-aerated (cultural treatment) using 1-inch solid tines. Two fungicide applications were performed on Oct 06, 2015 and Nov 03, 2015 at Towne Lake Hills Golf Club and on Oct 9, 2015 and Nov 10, 2015 at the Griffin location. The fungicide applications closely follow the proposed protocol of average soil temperatures in the primary root zone consistently above 60 F. A nontreated control was added for comparison. A light irrigation (0.25 inches) was applied immediately following fungicide applications. Visual ratings were performed at 15 to 30 day intervals from the initial application date and depending on disease activity. Visual estimates of SDS disease severity were made using a modified Horsfall-Barratt rating scale (0 to 11) that then are transformed to percent disease severity (0 = 1.17%, 5=37.5%, 11=98.82%). Turf Quality was rated using a percent (0=bad, unsightly quality; 100=excellent quality). Visual ratings and data have been recorded during disease incidence and when conditions for disease development existed (seven times since October 2015 through June 2016). Additional ratings are being conducted at this time and will continue through the end of summer of Digital photography has been taken along with visual ratings. Penthiopyrad (Velista) at 0.5 oz per 1000 sq ft. was added this year (fall 2015 and spring 2016) to the fungicide trials. This inclusion was outside of the proposed grant proposal but included due to a recent SDS fungicide labeling. Spring 2016: As per the original protocol, the areas were either core-aerated or not core-aerated (cultural treatment) using 1-inch solid tines. Two fungicide applications were performed on March 29, 2016 and April 26, 2016 at Towne Lake Hills Golf Club. The spring trial was performed at a fairway of # 17 th hole in Towne Lake. The fungicide applications were performed at the Griffin location on March 24, 2016 and April 20, Visual ratings were performed as described in the above paragraph. Digital photography is being taken along with visual ratings. Fungicide treatments consisted of: Tebuconazole (Torque) at 0.6 fl oz/1000 ft 2 Metconazole (Tourney) at 0.6 fl oz/1000 ft 2 Azoxystrobin + propiconazole (Headway) at 3 fl 1

2 oz/1000 ft 2 Azoxystrobin + difenconazole (Briskway) at 0.75 fl oz/1000 ft 2 Pyraclostrobin + triticonazole (Pillar) at 3 lb/1000 ft 2 Fenarimol (Rubigan) at 6 fl oz/1000 ft 2 Fluoxapyroxad (Xzemplar) at 0.26 fl oz/1000 ft 2 Tebuconazole (Torque) at 0.6 fl oz/1000 ft 2 + wetting agent (Revolution) at 6 fl oz /1000 ft 2 Non-treated control Figure 1. Overall view of Towne Lake Hills Golf Club and UGA Griffin Campus SDS Trials. PRELIMINARY RESULTS Field experiments have been finalized as of June 6, 2016 in both experimental locations. A massive amount of data has been collected from each of the trials at the two locations (2 locations, 2 timings, 2 cultural practices, 9 treatments, 4 replications, numerous observation dates =@ 3000 data points). Data is currently being sorted out and analyzed. 1. Core aereation (solid tine) cultural practice before fungicide application was statistically similar to non-core aereation in both, fall and spring. Thus, core aereation did not increased fungicide efficacy in spring or fall applications in any of the sites. Solid tine did not negatively impact fungicide efficacy either, neither promoted disease severity data indicates that, all fungicides treatments provided statistically significant Spring Dead Spot suppression when compared to the untreated control at both locations and times (Fig 2A and 2B). 3. There were statistically significant differences in disease suppressing among fungicide treatments both in fall and in spring. 4. Based on preliminary data analysis of disease suppression and disease suppression consistency in fall and in spring, fungicides were divided in three TIERS (Table 1) 5. TIER 1. Fluoxapyroxad (Xzemplar) at 0.26 fl oz/1000 ft2, Fenarimol (Rubigan) at 6 fl oz/1000 ft 2, and Azoxystrobin + difenconazole (Briskway) at 0.75 fl oz/1000 ft 2 provided the most significant and consistent control. 6. TIER 2. Tebuconazole (Torque) at 0.6 fl oz/1000 ft 2 + wetting agent (Revolution) at 6 fl oz /1000 ft 2, Metconazole (Tourney) at 0.6 fl oz/1000 ft 2 formed the second most efficacious group of fungicides. 7. TIER 3. Tebuconazole (Torque) at 0.6 fl oz/1000 ft 2, Azoxystrobin + propiconazole (Headway) at 3 fl oz/1000 ft 2, and pyraclostrobin + triticonazole (Pillar) at 3 lb/1000 ft 2 8. Preventive management of SDS using two fall fungicide applications provided significant disease suppression with the use of new (er) chemistries as well as with previously proven efficacious chemistries. 9. Spring fungicide applications proved to suppress SDS severity up to 60% compared to the untreated control resulting in the acceleration of turfgrass recovery up to 47-2

3 77 days (days to acceptable quality=foliar canopy was uniform in color and density). 10. An unforeseen benefit of spring fungicide applications is the control and /or prevention 10/06/14 10/31/14 04/07/15 of other diseases especially dollar spot and large patch. 05/06/15 05/20/15 06/05/15 06/24/15 A 10/01/14 04/08/15 06/25/15 06/30/15 B Figure 2. Fungicide Efficacy on SDS Control at UGA Griffin-Campus (A) and Towne Lake Hills Golf Club (B)

4 Table 1. Grouping of Fungicide by Efficacy on SDS. 2. EVALUATE THE EFFECT OF SOIL FERTILITY-WITH EMPHASIS OF NITROGEN SOURCE AND FUNGICIDE ALTERNATIVES FOR THE CONTROL OF SDS. Introduction Field experiments have been finalized as of June 3, 2016 in both experimental locations. Since the last report, monthly applications of different sources of nitrogen and bio-fungicides/organic products were performed during the remainder of summer and early fall of 2015 at a bermudagrass 419 fairway area on the 15 th hole at Towne Lake Hills Golf Club in Woodstock GA and at University of Georgia-Griffin campus on TifSport bermudagrass sward with SDS history. Materials and Methods At the Towne Lake Hills location, the monthly applications of the products where performed in 2015: 5 May, 2 Jun, 30 Jun, 28 Jul, 31 Aug. At the UGA Griffin location monthly applications were performed in 2015: 1 May, 30 May, 26 Jun, 24 Jul, 21 Aug, 18 Sept. Visual ratings were performed at 30- day intervals from the initial application date and depending on disease activity. using a modified Horsfall-Barratt rating scale (0 to 11) (where 0 = 1.17%, 5=37.5%, 11=98.82%). Turf Quality was rated using a percent (0=bad, unsightly quality; 100=excellent quality). Fertilizers and organic treatments consisting of a monthly application of: Ammonium nitrate, at a rate of 1 lb/1000 ft 2 Calcium nitrate, at a rate of 1 lb/1000 ft 2 Ammonium sulfate, at a rate of 1 lb/1000 ft fertilizers at a rate of 1 lb/1000 ft 2 Companion at 6 fl oz/1000 ft 2 (Bacillus subtillis GB03) Essential plus at 3 oz /1000 ft 2 (Humic acid, Plant extracts, sugars, kelp, organic N) Regalia at 3 oz fl oz /1000 ft 2 (Extract of Reynoutria sacchalinensis) Holganix at 7 fl oz /1000 ft 2 (Compost tea, Endo and Ectomycorrhizae) PRELIMINARY RESULTS: 1. These trials started during the summer which is the peak of the growing season. In general disease incidence was low in both locations. The highest disease severity only reached 10.5 %. 2. The effect of these different nitrogen sources and bio-fungicides/organic products was best observed when analyzing turf quality/turf recovery and after the second year of evaluation. 3. Monthly applications of calcium nitrate 1 lb/1000 ft 2, Ammonium nitrate,1 lb/1000 ft 2 and fertilizer 1 lb/1000 ft 2 provided statiscally significantly better turf quality/turf recovery (Fig 3). 4. Companion (Bacillus subtillis GB03) at 6 fl oz/1000 ft 2 and Holganix ft 2 (Compost tea, Endo and Ectomycorrhizae) at 7 fl oz /1000 4

5 also provided acceptable turf quality/turf recovery. fungicides/organic products were divided in TIERS (Table 2) 5. Based on preliminary data analysis of disease suppression and turfgrass quality different sources of nitrogen and bio- Figure 4. Effect of different sources of nitrogen and bio-fungicides/organic products on A) SDS disease severity and B) turfgrass quality

6 Table 2. Grouping of different sources of nitrogen and bio-fungicides/organic products by turfgrass quality/recovery and efficacy on SDS. PATH FORWARD 1. We will continue collecting data through July Currently we are compiling, analyzing and categorizing more than 3000 data entries. 3. Results from this research will provide information on preventative and curative management of SDS utilizing a multiprong-multiyear integrated strategy tailored specifically for Georgia. ACKNOWLEDGEMENTS 1. This research is being supported by the Georgia Golf Environmental Fund (GGEF). 2. We thank Mr. Richard Staughton (Towne Lake Hills Golf Club) for his valuable help and assistance while these SDS trials were carried out. 6