1998 Iowa Turfgrass Research Report

1998 Iowa Turfgrass Research Report

Evaluation of Fungicides for Control of Dollar Spot in Penncross Creeping Bentgrass - 1997

Mark L. Gleason

Trials were conducted at the turfgrass research area of Iowa State University's Horticulture Research Station north of Ames, Iowa. Fungicides were applied to Penncross creeping bentgrass maintained at 5/32-inch cutting height, using a modified bicycle sprayer at 30 psi and a dilution rate of 5 gal/1000 ft². The experimental design was a randomized complete block with four replications. All plots measured 4 ft x 5 ft.

Initial inoculation with the dollar spot pathogen was not fully successful, so fungicide applications were suspended July 2. After inoculation of the entire plot with pathogen-infested rye grain on August 4, spray applications began on August 8. Subsequent applications were made at specified intervals on August 27, August 29, September 5, and September 10.

Dollar spot symptoms appeared in the plot by August 18. Disease development was severe during late August and early September. Most, but not all, treatments exhibited significantly better dollar spot control than the untreated check on all three rating dates (see Table 1). No phytotoxicity symptoms were observed during the trial.

Table 1. 1997 Dollar Spot Trial at ISU Horticulture Station. Plot size 20 ft², 4 plots/trt; 80 ft² per treatment.

			Interval	% plot infected1
Trt.	Product	Rate/1000 ft2	(days)	Aug 29	Sept 7	Sept 14
1	Check	-----	----	42.5	42.5	40.0
2	Lynx 25 DF	0.5 oz	14	2.8	1.1	1.9
	+ chlorothalonil 4 F	3.0 fl oz
3	Lynx 25 DF	0.5 oz	21	19.3	4.5	11.8
	+ Heritage 50 DF	0.2 oz
4	Lynx 1% G	24.0 oz	28	18.0	13.0	8.3
5	Bayleton 25 DF	0.5 oz	14	8.0	2.8	9.5
	+ Chlorothalonil 4 F	3.0 fl oz
6	Bayleton 25 DF	0.5 oz	21	16.8	8.3	22.5
	+ Heritage 50 DF	0.2 oz
7	Bayleton 25 DF	0.5 oz	14	25.0	8.3	19.3
8	Thalonil 4 L	4.0 fl oz	14	37.5	23.8	26.3
	+ Heritage 50 WG	0.2 oz
9	Thalonil 4 L	6.0 fl oz	14	9.8	4.3	10.0
	+ Heritage 50 WG	0.2 oz
10	Thalonil 4 L	4.0 fl oz	14	40.0	31.8	41.3
11	Thalonil 4 L	6.0 fl oz	14	22.0	7.3	13.8
12	CONFIDENTIAL	-----	---	20.0	23.8	30.0
13	CONFIDENTIAL	-----	---	16.3	9.0	18.8
14	CONFIDENTIAL	-----	---	30.3	16.3	24.0
15	CONFIDENTIAL	-----	---	1.0	0.0	0.1
16	CONFIDENTIAL	-----	---	11.3	3.5	9.5
17	CONFIDENTIAL	-----	---	3.5	0.5	1.1
18	CONFIDENTIAL	-----	---	1.5	0.1	0.1
19	Daconil Ultrex 82.5 WDG	3.8 oz	14	6.5	2.5	5.5
20	IB 11522	4.1 oz	14	18.3	8.3	14.5
21	Daconil Ultrex 82.5 WDG	3.0 oz	14	7.8	4.4	10.8
	+ Heritage 50 WG	0.2 oz
22	Heritage 50 WG	0.2 oz	28	31.3	36.3	41.3
23	EXP 10790 (26 GT) 2 SC	3.0 fl oz	14	33.3	22.8	23.0
	ALTERNATE WITH
	Heritage 50 WG	0.2 oz	28
	+EXP 10790(26 GT) 2 SC	3.0 fl oz
24	Daconil Ultrex 82.5 WDG	3.1 oz	14	12.3	5.0	11.8
	ALTERNATE WITH
	Heritage 50 WG	0.2 oz	28
	+ Daconil Ultrex 82.5 WDG	3.1 oz
25	Chipco Aliette Signature 80 WG	4.0 oz	14	37.5	25.0	37.5
	+ EXP 10790 (26 GT) 2 SC	3.0 fl oz
	ALTERNATE WITH
	Heritage 50 WG	0.2 oz	28
	+ Chipco Aliette Signature 80 WC	4.0 oz
	+ EXP 10790 (26 GT) 2 SC	3.0 fl oz
26	Chipco Aliette Signature 80 WC	4.0 oz	14	31.3	21.5	20.0
	+ EXP 10790 (26 GT) 2 SC	3.0 fl oz
	3336 F	2.0 fl oz	14	2.0	0.0	0.0
	+ Chipco 26019 FLO	2.0 fl oz
28	CTM 90 WDG	4.0 oz	14	0.9	0.0	0.0
29	CTM 90 WDG	8.0 oz	14	0.03	0.0	0.0
30	Turfcide 400	4.5 fl oz	14	45.0	23.8	21.3
31	Turfcide 75 WC	3.0 oz	14	30.0	22.0	25.0
32	Turfcide 75 WC	3.0 oz	14	13.8	9.0	11.3
	+ Daconil Ultrex 82.5 WDG	2.0 oz
33	Daconil Ultrex 82.5 WDG	2.0 oz	14	27.5	21.8	28.8
34	Turfcide 75 WG	3.0 oz	14	23.8	14.0	21.8
	+ Spotrete 75 WDC	3.0 oz
35	Spotrete 75 WDG	3.0 oz	14	30.0	31.3	37.5
36	Turfcide 75 WG	3.0 oz	14	18.8	5.3	20.0
	+ Terraguard 50 W	2.0 oz
37	Terraguard 50 W	2.0 oz	14	6.9	3.5	9.3
38	Eagle 40 W	0.6 oz	21	4.0	1.4	5.3
39	Eagle 40 W	0.6 oz	14	1.8	0.3	2.0
	ALTERNATE WITH
	Fore 75 DG	6.0 oz	14
	LSD2			1637	10.5	11.9

¹n = 4

²Least Significant Difference, P=0.05.

ISU Horticulture:Publications:1998 Turfgrass Report

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