Introduction

The purpose of this trial was to evaluate the effectiveness of various fungicides and fungicide programs in controlling anthracnose (Colletotrichum cereale) on annual bluegrass putting greens.

Materials and Methods

The trial was initiated on June 26th on an annual bluegrass putting green located at Emerald Valley Golf Club in Cresswell, Oregon. Subsequent fungicide applications were applied every 3 weeks on July 18th, August 8th, August 29th, and September 19th.

The site is used daily as a chipping green with the first rep located on a sand base and the last two reps on a soil base. The course has a history of anthracnose problems with documented strobilurin and thiophanate methyl resistance (2006 analysis at Turf Pathology Laboratory at University of California at Riverside).

Individual plots measured 25 sq ft (5 X 5). Products were applied with a CO2-powered sprayer using TeeJet 80015 nozzles at 30 psi producing a total spray volume of two gallons per 1,000 square feet. Treatments are listed in table 1.

The green was mowed daily at 0.125 inches using a triplex greens mower. Before the trial started, the green had been fertilized on a biweekly schedule of 0.25 lbs nitrogen per 1,000 square feet. After initiation of the trial, fertilizer was withheld until the first week of August. Biweekly fertilizer applications were resumed at that time. Irrigation was applied with a RainBird irrigation system with supplemental hand watering. Light sand topdressing was applied on a biweekly basis.

Percent disease and plot quality ratings were made on all fungicide application dates plus a final rating on October 1. Data from each rating date were subjected to analysis of variance using a randomized complete block design with 3 replications. Differences between means were determined by LSD at the 5% level.

Results

Disease symptoms were first observed in mid-July. By August 8th, the untreated check plots averaged 9.3 percent disease, and by October 1st, the untreated plots averaged nearly 32% disease coverage. Disease ratings are presented in table 1 and figure 1 shows several treatments with variable amounts of disease.

Seven treatments had 0.4% or less disease:

# 5 A7402 @ 0.62 oz
# 6 A7402 @ 0.94 oz
# 15 Lynx @ 1.5 oz
# 16 Lynx @ 2.0 oz
# 18 Signature + Lynx @ 4.0 oz + 1.0 oz
# 19 Lynx @ 1.5 oz rotated with Signature and Daconil Ultrex @ 4.0 oz + 3.2 oz
# 20 Lynx @ 1.5 oz in June, Signature plus Daconil Ultrex @ 4.0 oz + 3.2 oz in July and August, and Lynx again @ 1.5 oz in September.

Three of the above treatments had no disease - the two Lynx treatments and the treatment with Lynx rotated with Signature and Daconil.

Two treatments had less than 1% disease:

# 13 Instrata (propiconazole, chlorothalanil, and fludioxonil) @ 6.0 oz
# 14 Trinity @ 1.0 oz

The disease level in the above two treatments would be tolerable to some superintendents but the turf quality was in the low 6 range compared with the first seven treatments that had turf quality generally in the 7.0 to 8.0 range. Instrata at the 6 oz rate produced excellent turf quality in the middle of the trial (8/29) which rated 8.0, but the quality declined to 6.3 by October 1st. Trinity had turf quality ratings of 6.8 and 7.0 on August 29th and September 18th, respectively. Both of these treatments would be effective in a fungicide rotation program.

Two treatments had less than 2 % disease:

# 3 A7402 @ 0.31 oz
# 12 Instrata @ 4.5 oz

Disease control of these treatments was better than the untreated check plots, but this level of disease would be unacceptable at most golf clubs.

Two treatments had 3.3 to 4.3 % disease on Oct 1:

# 2 A7402 at the 0.16 oz
# 11 Concert (propiconazole and chlorothalanil) @ 6.0 oz

This level of disease would be generally unacceptable. Concert actually held up well through August (0.9 percent disease on August 29th) before faltering in the latter part of the trial.

Treatments with more than 6 % disease:

# 6 Banner Maxx @ 0.5 oz
# 7 Banner Maxx @ 1.0 oz
# 8 Banner Maxx @ 1.5 oz
# 9 A6780 @ 0.5 oz
# 10 A6780 @ 1.0 oz
# 17 Signature + Daconil Ultrex @ 4.0 oz + 3.2 oz

All of these treatments produced unacceptable Anthracnose control throughout the trial. Banner Maxx, which has been a key product for Anthracnose control gave surprisingly poor control. We believe this was due to the low rates used in the trial and is not likely an indication of resistance to this fungicide. Minimum rates of Banner Maxx should probably be 2 oz or higher to ensure control.

Turf Quality Ratings

High turf quality ratings correlated very closely with low percent disease ratings (tables 1 & 2). Top treatments rated 7 or higher by the end of the trial, while the untreated check plots averaged a woeful 2.7.

For organization purposes, we have broken turf quality ratings into three tiers: excellent or very good turf quality, acceptable, and unacceptable.

Excellent to very good turf quality (7 or higher):

# 16 Lynx @ 2 oz
# 19 Lynx @ 1.5 oz rotated with Signature & Daconil Ultrex @ 4 oz + 3.2 oz
# 15 Lynx @ 1.5 oz
# 18 Signature @ 4 oz + Lynx @ 1 oz oz
# 5 A7402 @ 0.94 oz
# 20 Lynx @ 1.5 oz in June, Signature + Daconil @ 4.0 oz + 3.2 oz in July & August, and Lynx @ 1.5 ounces in September

Acceptable turf quality (5.8 to 6.7):

# 4 A7402 @ 0.62 #13 Instrata @ 6.0 oz
#14 Trinity @ 1.0 oz # 3 A7402 @ 0.31 oz
#12 Instrata @ 4.5 oz

Unacceptable turf quality (5.0 or lower).

# 1 Untreated check
# 2 A7402 @ 0.16 oz # 6 Banner Maxx @ 0.5 oz
# 7 Banner Maxx @ 1.0 oz
# 8 Banner Maxx @ 1.5 oz # 9 A6780 @ 0.5 oz
# 10 A6780 @ 1.0 oz
# 11 Concert @ 6.0 oz
# 17 Signature + Daconil Ultrex @ 4.0 oz + 3.2 oz

Poor turf quality in these plots reflects poor disease control and may be exaggerated by the low nitrogen fertility levels maintained during the trial. Once fertilizer applications were resumed plot quality did improve in all plots.

Table 1: Anthracnose disease ratings     %DiseaseCoverage      18-Jul8-Aug29-Aug18-Sep1-OctTrt #Treatment"Rates/1000sq ft" AvgAvgAvgAvgAvg1ChecknaFL oz0.89.316.72531.72A74020.16FL oz0.10.93.73.74.33A74020.31FL oz0.10.31.71.21.74A74020.62FL oz0.30.20.40.10.35A74020.94FL oz00000.26Banner Maxx 1.3 ME0.5FL oz0.11.357.712.77Banner Maxx 1.3 ME1FL oz01.96.28.39.38Banner Maxx 1.3 ME1.5FL oz02.46.26.310.79A67800.5FL oz0.13.556.71010A67801FL oz0.13559.311Concert6FL oz00.30.91.43.312Instrata4.5FL oz00.311.41.513Instrata6FL oz0.200.20.40.814Trinity1FL oz00.70.70.20.715Lynx1.5FL oz0.3000016Lynx2FL oz0.2000017Signature + Daconil4 + 3.2WT oz0.41.83.756.718Signature + Lynx4 + 1WT /Liq oz00.20.20.20.119Lynx rotated with Signature + Daconil1.5/4 + 3.2FL oz/WT oz0000020Lynx in June/Sig + Dac in July & Aug/Lynx in Sept1.5/4 + 3.2FL oz/WT oz000.10.50.4   LSD @ .050.32.73.74.95.6

Table 2: Plot Quality: 1 – 9; 9 = best Plot Quality     18-Jul8-Aug29-Aug18-Sep1-OctTrt#Treatment"Rates/1000 sq ft" AvgAvgAvgAvgAvg1ChecknaFL oz64.33.23.22.72A74020.16FL oz5.7654.84.73A74020.31FL oz5.76.25.86.25.84A74020.62FL oz5.76.76.776.75A74020.94FL oz5.76.777.276Banner Maxx 1.3 ME0.5FL oz5.85.74.54.23.77Banner Maxx 1.3 ME1FL oz5.55.34.74.74.28Banner Maxx 1.3 ME1.5FL oz6.35.74.74.549A67800.5FL oz64.74.74.3410A67801FL oz654.74.54.211Concert6FL oz67.36.75.8512Instrata4.5FL oz67.376.35.813Instrata6FL oz6.37.386.86.314Trinity1FL oz5.76.76.876.215Lynx1.5FL oz677.87.77.516Lynx2FL oz6.37.38.37.7817Signature + Daconil4 + 3.2WT oz65.74.84.54.518Signature + Lynx4 + 1WT /Liq oz5.86.37.27.77.219Lynx rotated with Signature + Daconil1.5/4 + 3.2FL oz/WT oz67.387.57.820Lynx in June/Sig + Dac in July & Aug/Lynx in Sept1.5/4 + 3.2FL oz/WT oz67.77.26.87   LSD @ .050.71.51.31.21.3

Figure 1: Relative disease activity from selected treatments