Evaluation of Experimental fungicide applications on dollar spot disease caused by Sclerotinia homoeocarpa In creeping bentgrass maintained as a golf course fairway
HOST – CREEPING BENTGRASS (Agrostis stolonifera ‘Providence’) DISEASE – Dollar spot (Sclerotinia homoeocarpa)
J. Roberts, G. Achenef, J. Doherty and C. Beckley
12 8 17 18 20 6 1 15 10 21 7 3 19 16 14 13 11 2 5 9 4 13 17 14 19 11 5 6 18 3 1 20 16 9 21 4 12 10 8 15 2 7 11 8 5 21 3 2 19 7 16 9 15 14 10 18 20 17 1 6 12 13 4 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 # Treatment Rate
oz. 1000 ft-2 Spray Interval
1. A7087 0.5 fl 14 d 2. A22063 0.5 fl 14 d 3. A21705 4.34 fl 14 d 4. A19275 2.0 fl 14 d 5. A7087 0.5 fl 21 d 6. A22063 0.5 fl 21 d 7. A21705 4.34 fl 21 d 8. A19275 3.0 fl 21 d 9. A19649 A22063 0.118 fl 0.359 fl 21 d 10. A19649 A22063 0.157 fl 0.359 fl 21 d 11. A19649 A22063 0.176 fl 0.359 fl 21 d 12. A20866 0.21 fl 21 d 13. A19649 A22063 0.157 fl 0.5 fl 28 d 14. A19649 A22063 0.209 fl 0.5 fl 28 d 15. A19649 A22063 0.236 fl 0.5 fl 28 d 16. A20866 0.26 fl 28 d 17. A19649 A22063 0.157 fl 0.5 fl 35 d 18. A19649 A22063 0.209 fl 0.5 fl 35 d 19. A19649 A22063 0.236 fl 0.5 fl 35 d 20. A20866 0.26 fl 35 d 21. Non-treated check
Experimental fungicides were evaluated for control of dollar spot disease, caused by Sclerotinia homoeocapra. This trial was conducted at the Paint Branch Turfgrass Research Facility in College Park, MD on ‘Crenshaw’ creeping bentgrass maintained under fairway height conditions. Mowing was performed 3 times weekly at a height of 0.40 in. Irrigation was applied to prevent drought stress. The entire plot area received 3.0 lb N 1000 ft-2over the past year. Dimension (i.e., dithiopyr) was applied at 0.55 oz 1000 ft-2on 17 May to prevent weed encroachment.
Treatments were arranged in a randomized complete block design with 4 replications. Treatments were applied to 3’ x 6’ plots using TeeJet AI9508E (2 gal 1000 ft-2) air induction nozzles powered by a
CO2 pressurized backpack sprayer. All treatments were initiated on 15 May. Treatments having a 14 d
application schedule were reapplied on 30 May, 12, and 26 June, 10 and 17 July. Treatments having a 21 d application schedule were reapplied on 6 and 26 June, 17 July. Treatments having a 28 d application schedule were reapplied on 12 June and 10 July. Treatments having a 35 d application schedule were applied on 19 June and 23 July. The experimental area was evaluated every 7-14 days throughout the growing season and ratings included counts of dollar spot infection centers, turf quality (scale 1-9: 1=dead, 9=best, and 6=minimum acceptable), and turf color using NDVI.
Dollar spot disease developed naturally in the experimental area and progressed rapidly in the non-treated control plots. All fungicide treatments, irrespective of their application interval, showed significant reduction in dollar spot compared to the non-treated check. Of the experimental products tested using a 14 d interval, all nearly eliminated dollar spot compared to the non-treated with the exception of A19275, which had significantly higher dollar spot than all other 14 d treatments on 5 of 7 rating dates and when comparing AUDPC. A19275 behaved similarly when comparing 21 d single and tank mix applications. All other 21 d treatments had little dollar spot development with the exception of and A7087, which tended to have breakthrough when extending intervals beyond 14 d. All tank mix combinations and A20866 applied alone were very effective at both 21 and 28 d intervals. Some breakthrough was observed when extending A20866 to 28 d application intervals and even more when applied at 35 day intervals. The additional tank mix combinations tested at 35 d intervals developed considerable dollar spot (i.e. >20 ICs) when extended the second third application beyond 28 d. Turf quality results followed similar trends with disease ratings and all products improved turf quality when compared to the non-treated check. Turf color ratings were also similar to turf quality ratings as turf color was a component of turf quality ratings.
Table 1.
Influence of experimental fungicide applications on dollar spot disease caused by Sclerotinia
homoeocarpa in creeping bentgrass maintained as a golf course fairway
Treatmenty and Rate
1000 ft2 App Interval
# Dollar Spot Disease
05-24-17 05-30-17 06-06-17 06-19-17 06-26-17 07-10-17 07-25-17 A7087 0.50 fl oz 14 day 6.2Z a 1.1 d-g 0.0 g 0.0 e 0.0 f 0.2 gh 0.0 e A22063 0.50 fl oz 14 day 13.0 a 4.3 bcd 0.5 fg 0.0 e 0.2 ef 0.6 gh 0.6 de A21705 4.34 fl oz 14 day 20.3 a 1.7 c-f 1.4 ef 0.2 e 0.0 f 2.7 efg 0.3 de A19275 2.00 fl oz 14 day 7.1 a 32.0 a 9.2 bc 0.7 de 25.0 c 62.4 b 44.1 bc A7087 0.50 fl oz 21 day 10.1 a 5.5 bc 7.4 cd 3.8 c 70.6 b 27.3 bc 2.0 d A22063 0.50 fl oz 21 day 9.5 a 2.6 b-e 2.6 e 2.6 cd 28.5 c 6.4 de 1.6 de A21705 4.34 fl oz 21 day 10.2 a 1.9 c-f 2.9 de 0.6 de 15.3 c 5.6 def 2.2 d A19275 3.00 fl oz 21 day 5.2 a 7.2 b 19.5 b 2.5 cd 58.7 b 15.1 cd 0.6 de A19649 0.118 fl oz A22063 0.359 fl oz 21 day 5.6 a 0.3 fg 0.2 fg 0.0 e 0.2 ef 1.2 fgh 0.0 e A19649 0.157 fl oz A22063 0.359 fl oz 21 day 3.8 a 0.0 g 0.0 g 0.0 e 0.0 f 0.2 gh 0.0 e A19649 0.176 fl oz A22063 0.359 fl oz 21 day 8.8 a 0.2 fg 0.0 g 0.2 e 0.0 f 0.0 h 0.0 e A20866 0.21 fl oz 21 day 4.5 a 0.4 efg 7.7 cd 0.6 de 1.1 de 0.0 h 0.0 e A19649 0.157 fl oz
A22063 0.500 fl oz 28 day 4.2 a 0.2 fg 0.0 g 0.0 e 0.0 f 4.3 def 0.9 de A19649 0.209 fl oz
A22063 0.500 fl oz 28 day 7.9 a 0.4 efg 0.4 fg 0.0 e 0.0 f 5.7 def 0.9 de A19649 0.236 fl oz
A22063 0.500 fl oz 28 day 6.3 a 0.2 fg 0.0 g 0.0 e 0.0 f 4.6 def 0.0 e A20866 0.26 fl oz 28 day 4.2 a 0.9 efg 1.3 ef 0.3 e 0.0 f 12.1 cd 2.7 d A19649 0.157 fl oz
A22063 0.500 fl oz 35 day 7.7 a 0.0 g 0.0 g 4.5 c 0.2 ef 1.6 e-h 23.0 c A19649 0.209 fl oz
A22063 0.500 fl oz 35 day 6.4 a 0.7 efg 0.0 g 2.5 cd 0.2 ef 1.4 e-h 59.8 bc A19649 0.236 fl oz
A22063 0.500 fl oz 35 day 9.3 a 0.3 fg 0.0 g 2.5 cd 0.0 f 1.3 e-h 59.9 bc A20866 0.260 fl oz 35 day 11.1 a 2.1 b-f 2.6 e 32.6 b 2.3 d 2.1 e-h 81.9 ab Untreated Check 14.1 a 72.7 a 93.8 a 121.1 a 205.6 a 214.7 a 211.3 a
Source of Variation Pr>F
Treatment NS *** *** *** *** *** ***
YTreatments were applied at the specified intervals from 15 May 2017 using a CO2 backpack sprayer equipped with a Teejet AI9508E nozzle.
ZValues are means of 4 replicates. Means within columns followed by the same letter are not significantly different according to LSD test (p<0.05) *Significant at 0.05 probability
Table 1. Cont.
Influence of experimental fungicide applications on dollar spot disease caused by Sclerotinia homoeocarpa in creeping bentgrass maintained as a golf course fairway
Treatmenty and Rate 1000 ft2
App Interval
# Dollar Spot Disease 08-11-17 AUDPCX A7087 0.50 fl oz 14 day 0.0Z e 32.75 hi A22063 0.50 fl oz 14 day 0.2 e 113.75 hi A21705 4.34 fl oz 14 day 0.0 e 204.50 hi A19275 2.00 fl oz 14 day 13.9 a 2885.25 b A7087 0.50 fl oz 21 day 2.7 a-e 1937.00 cd A22063 0.50 fl oz 21 day 9.1 ab 902.75 e-h A21705 4.34 fl oz 21 day 6.9 a-d 569.13 f-i A19275 3.00 fl oz 21 day 7.7 abc 1446.38 cde A19649 0.118 fl oz
A22063 0.359 fl oz 21 day 1.3 b-e 74.50 hi A19649 0.157 fl oz A22063 0.359 fl oz 21 day 0.9 de 28.50 i A19649 0.176 fl oz A22063 0.359 fl oz 21 day 0.0 e 35.63 i A20866 0.21 fl oz 21 day 0.2 e 137.75 hi A19649 0.157 fl oz A22063 0.500 fl oz 28 day 0.4 e 194.63 hi A19649 0.209 fl oz A22063 0.500 fl oz 28 day 0.0 e 253.75 hi A19649 0.236 fl oz
A22063 0.500 fl oz 28 day 1.9 b-e 110.79 hi A20866 0.26 fl oz 28 day 0.3 e 302.88 ghi A19649 0.157 fl oz
A22063 0.500 fl oz 35 day 0.0 e 716.88 e-i A19649 0.209 fl oz
A22063 0.500 fl oz 35 day 0.3 e 1123.38 d-g A19649 0.236 fl oz
A22063 0.500 fl oz 35 day 0.2 e 1187.50 def A20866 0.260 fl oz 35 day 1.0 cde 2060.25 bc Untreated Check 12.6 a 11676.75 a Source of Variation Pr>F
Treatment *** ***
XArea under disease progress curve (AUDPC) values were calculated using the trapezoidal method as defined by Madden et al., 2007.
YTreatments were applied at the specified intervals from 15 May 2017 using a CO2 backpack sprayer equipped with a Teejet AI9508E nozzle.
ZValues are means of 4 replicates. Means within columns followed by the same letter are not significantly different according to LSD test (p<0.05) *Significant at 0.05 probability
Table 2.
Influence of experimental fungicide applications on turf quality of creeping bentgrass maintained as a golf course fairway
Treatmenty and Rate 1000 ft2
App Interval
Turf Quality (1 to 9; 6=acceptable)
05-24-17 05-30-17 06-06-17 06-19-17 06-26-17 07-10-17 07-25-17 A7087 0.50 fl oz 14 day 5.75Z a 6.25 a 7.00 a 7.25 a 7.38 ab 7.25 ab 6.75 abc A22063 0.50 fl oz 14 day 5.38 a 5.75 abc 6.25 b-e 7.00 ab 7.75 a 7.63 a 6.63 a-d A21705 4.34 fl oz 14 day 5.00 a 5.88 abc 5.75 de 6.00 d 6.50 cde 6.50 b-e 5.88 def A19275 2.00 fl oz 14 day 5.63 a 4.75 d 5.63 ef 6.88 abc 5.88 efg 5.25 g 5.13 fgh A7087 0.50 fl oz 21 day 5.38 a 5.63 bc 5.63 ef 6.63 a-d 4.88 h 5.63 fg 6.50 a-d A22063 0.50 fl oz 21 day 5.38 a 5.88 abc 6.0 cde 6.25 bcd 5.50 fgh 6.25 c-f 6.63 a-d A21705 4.34 fl oz 21 day 5.38 a 6.00 ab 5.88 cde 6.13 cd 5.75 efg 6.50 b-e 6.38 bcd A19275 3.00 fl oz 21 day 6.00 a 5.38 c 5.0 f 6.75 a-d 5.13 gh 6.13 c-f 7.25 a A19649 0.118 fl oz
A22063 0.359 fl oz 21 day 5.75 a 6.13 ab 6.50 abc 6.75 a-d 6.75 bcd 6.63 bcd 6.75 abc A19649 0.157 fl oz
A22063 0.359 fl oz 21 day 6.13 a 6.25 a 6.75 ab 7.00 ab 7.13 abc 7.13 ab 7.13 ab A19649 0.176 fl oz
A22063 0.359 fl oz 21 day 5.38 a 5.75 abc 6.5 abc 7.13 a 7.35 ab 7.13 ab 6.75 abc A20866 0.21 fl oz 21 day 5.88 a 6.00 ab 5.75 de 7.13 a 7.13 abc 6.88 abc 6.75 abc A19649 0.157 fl oz
A22063 0.500 fl oz 28 day 6.00 a 6.25 a 6.38 a-d 6.88 abc 7.38 ab 6.50 b-e 6.00 cde A19649 0.209 fl oz
A22063 0.500 fl oz 28 day 5.63 a 6.13 ab 6.38 a-d 6.88 abc 7.50 ab 6.50 b-e 6.13 cde A19649 0.236 fl oz
A22063 0.500 fl oz 28 day 5.63 a 6.13 ab 6.38 a-d 6.63 a-d 6.88 bcd 6.13 c-f 6.13 cde A20866 0.26 fl oz 28 day 5.75 a 6.13 ab 6.00 cde 6.25 bcd 6.38 cde 5.75 efg 5.38 efg A19649 0.157 fl oz
A22063 0.500 fl oz 35 day 5.63 a 6.00 ab 6.25 b-e 6.50 a-d 7.13 abc 6.88 abc 4.88 gh A19649 0.209 fl oz
A22063 0.500 fl oz 35 day 5.75 a 6.00 ab 6.50 abc 6.25 bcd 6.88 bcd 6.50 b-e 4.88 gh A19649 0.236 fl oz
A22063 0.500 fl oz 35 day 5.38 a 6.00 ab 6.25 b-e 6.25 bcd 6.50 cde 6.25 c-f 4.63 gh A20866 0.260 fl oz 35 day 5.38 a 6.00 ab 5.88 cde 5.00 e 6.25 def 6.00 d-g 4.38 h Untreated Check 5.38 a 4.25 d 3.88 g 3.63 f 3.38 i 3.00 h 3.38 i
Source of Variation Pr>F
Treatment NS *** *** *** *** *** ***
YTreatments were applied at the specified intervals from 15 May 2017 using a CO2 backpack sprayer equipped with a Teejet AI9508E nozzle.
ZValues are means of 4 replicates. Means within columns followed by the same letter are not significantly different according to LSD test (p<0.05) *Significant at 0.05 probability
Table 2. Cont.
Influence of experimental fungicide
applications on turf quality of creeping bentgrass maintained as a golf course fairway
Treatmenty and Rate
1000 ft2 App Interval
Turf Quality (1 to 9; 6=acceptable) 08-11-17 AUQPCX A7087 0.50 fl oz 14 day 8.00Z a 556.81 a A22063 0.50 fl oz 14 day 7.83 ab 548.75 ab A21705 4.34 fl oz 14 day 7.33 a-d 489.87 d-g A19275 2.00 fl oz 14 day 5.83 g 443.56 hi A7087 0.50 fl oz 21 day 6.17 efg 465.06 ghi A22063 0.50 fl oz 21 day 6.33 d-g 484.31 efg A21705 4.34 fl oz 21 day 6.83 b-g 490.19 d-g A19275 3.00 fl oz 21 day 6.00 fg 482.19 e-h A19649 0.118 fl oz
A22063 0.359 fl oz 21 day 6.67 c-g 520.81 a-e A19649 0.157 fl oz
A22063 0.359 fl oz 21 day 7.00 a-f 548.12 ab A19649 0.176 fl oz
A22063 0.359 fl oz 21 day 6.67 c-g 535.61 abc A20866 0.21 fl oz 21 day 7.17 a-e 528.44 a-d A19649 0.157 fl oz
A22063 0.500 fl oz 28 day 6.17 efg 510.87 b-f A19649 0.209 fl oz
A22063 0.500 fl oz 28 day 6.17 efg 511.19 b-f A19649 0.236 fl oz
A22063 0.500 fl oz 28 day 6.00 fg 497.75 c-g A20866 0.26 fl oz 28 day 7.17 a-e 476.44 f-i A19649 0.157 fl oz
A22063 0.500 fl oz 35 day 6.80 b-g 493.04 d-g A19649 0.209 fl oz
A22063 0.500 fl oz 35 day 7.67 abc 491.94 d-g A19649 0.236 fl oz
A22063 0.500 fl oz 35 day 7.33 a-d 474.62 f-i A20866 0.260 fl oz 35 day 6.33 d-g 440.69 i Untreated Check 4.67 h 291.00 j
Source of Variation Pr>F
Treatment *** ***
XArea under quality progress curve (AUQPC) values were calculated using the trapezoidal method as defined by Madden et al., 2007.
YTreatments were applied at the specified intervals from 15 May 2017 using a CO2 backpack sprayer equipped with a Teejet AI9508E nozzle. ZValues are means of 4 replicates. Means within columns followed by the same
letter are not significantly different according to LSD test (p<0.05) *Significant at 0.05 probability
Table 3.
Influence of experimental fungicide applications on turf color of creeping bentgrass maintained as a golf course fairway
Treatmenty and Rate 1000 ft2
App Interval
Turf Color (1 to 9; 6=acceptable)
05-30-17 06-06-17 06-19-17 07-10-17 07-25-17 08-11-17 AUCPCX A7087 0.50 fl oz 14 day 0.88Z b-e 0.88 ab 0.86 a 0.84 abc 0.86 a 0.89 a 68.01 ab A22063 0.50 fl oz 14 day 0.89 abc 0.88 ab 0.85 ab 0.85 a 0.85 abc 0.88 ab 68.19 a A21705 4.34 fl oz 14 day 0.88 b-e 0.87 b 0.83 cd 0.84 a-d 0.83 cde 0.88 abc 67.07 bcd A19275 2.00 fl oz 14 day 0.88 cde 0.88 ab 0.85 abc 0.83 bcd 0.84 b-e 0.87 cd 67.21 abc A7087 0.50 fl oz 21 day 0.88 cde 0.87 ab 0.85 abc 0.84 a-d 0.85 a-d 0.87 bcd 67.40 abc A22063 0.50 fl oz 21 day 0.88 de 0.87 b 0.84 bcd 0.84 abc 0.86 a 0.88 abc 67.42 abc A21705 4.34 fl oz 21 day 0.88 cde 0.87b 0.84 a-d 0.84 abc 0.85 abc 0.88 abc 67.52 abc A19275 3.00 fl oz 21 day 0.89 abc 0.88 ab 0.85 ab 0.85 a 0.86 a 0.88 abc 68.12 a A19649 0.118 fl oz
A22063 0.359 fl oz 21 day 0.88 b-e 0.87 ab 0.85 abc 0.83 a-d 0.85 ab 0.88 abc 67.59 abc A19649 0.157 fl oz
A22063 0.359 fl oz 21 day 0.88 b-e 0.88 ab 0.84 a-d 0.84 abc 0.86 a 0.88 abc 67.79 abc A19649 0.176 fl oz
A22063 0.359 fl oz 21 day 0.88 cde 0.88 ab 0.84 a-d 0.84 abc 0.83 cde 0.88 abc 67.33 abc A20866 0.21 fl oz 21 day 0.88 b-e 0.88 ab 0.85 ab 0.85 ab 0.85 ab 0.88 ab 68.09 a A19649 0.157 fl oz
A22063 0.500 fl oz 28 day 0.89 ab 0.89 a 0.85 ab 0.84 a-d 0.84 b-e 0.88 abc 67.73 abc A19649 0.209 fl oz
A22063 0.500 fl oz 28 day 0.89 abc 0.88 ab 0.85 abc 0.83 a-d 0.84 b-e 0.87 cd 67.40 abc A19649 0.236 fl oz
A22063 0.500 fl oz 28 day 0.88 b-e 0.88 ab 0.84 abc 0.83 a-d 0.85 ab 0.87 cd 67.52 abc A20866 0.26 fl oz 28 day 0.88 b-e 0.87 ab 0.84 bcd 0.82 bcd 0.82 e 0.88 abc 66.93 cd A19649 0.157 fl oz
A22063 0.500 fl oz 35 day 0.89 abc 0.88 ab 0.85 ab 0.84 abc 0.83 de 0.88 abc 67.55 abc A19649 0.209 fl oz
A22063 0.500 fl oz 35 day 0.90 a 0.89 a 0.84 a-d 0.84 abc 0.83 cde 0.89 a 67.53 abc A19649 0.236 fl oz
A22063 0.500 fl oz 35 day 0.90 a 0.87 ab 0.84 a-d 0.82 cd 0.82 e 0.88 abc 66.82 cd A20866 0.260 fl oz 35 day 0.89 a-d 0.87 b 0.83 d 0.81 d 0.82 e 0.87 cd 66.11 d Untreated Check 0.75 e 0.85 c 0.79 e 0.74 e 0.79 f 0.86 d 63.30 e
Source of Variation Pr>F
Treatment ** * *** *** *** * ***
XArea under Color progress curve (AUCPC) values were calculated using the trapezoidal method as defined by Madden et al., 2007. YTreatments were applied at the specified intervals from 15 May 2017 using a CO2 backpack sprayer equipped with a Teejet AI9508E
nozzle.
ZValues are means of 4 replicates. Means within columns followed by the same letter are not significantly different according to LSD test (p<0.05)
*Significant at 0.05 probability
