1999 Iowa Turfgrass Research Report

Trials were conducted at Veenker Memorial Golf Course on the campus of Iowa State University. Fungicides were applied to creeping bentgrass maintained at 5/32-inch cutting height, using a modified bicycle sprayer at 30 psi and a dilution rate of 5 gal/1,000 ft². The experimental design was a randomized complete block with four replications. All plots measured 4 ft x 5 ft. All plots were bordered on opposite sides by 1-ft-wide strips of untreated turf in order to help create uniform disease pressure.

Fungicide applications began on May 22 (Bio-Trek treatments only). The remainder of the treatments received the first application on June 10. Subsequent applications were made on June 17, 19, and 24; and July 1, 8, 15, and 22.

Brown patch symptoms were first observed on June 29. Disease development on untreated check plots &emdash; expressed on a 0-5 scale (0=no disease, 1=1=5%, 2=5-10%, 3=10-25%, 4=25-50%, 5=>50%) &emdash; was light on June 29 and moderate on July 10 and 22. Most, but not all, fungicide treatments exhibited significantly (LSD, P=0.05) less disease than the untreated check.

Phytotoxicity (browning of tips of grass blades) on plots treated with AMV 300 became progressively worse during July, and was more severe at the higher rate of product.

Table 1. 1998 Brown Patch Trial - WOI creeping bentgrass greens, Veenker Memorial Golf Course, ISU.

			Interval	Mean disease ratinga
Trt	Product	Rate/1,000 ft2	(days)	June 29	July 10	July 22
1	-----	------	--	1.75	3.25	2.50
2	Bio-Trek G	1.5 lb	late May	1.25	0.00	0.25
	Bio-Trek G	1.5 lb	4 wks later
	Bio-Trek WP	6 oz	10 days later
	Heritage	0.2 oz	21
3	Bio-Trek G	1.5 lb	late May	0.25	0.25	0.00
	Bio-Trek G	1.5 lb	4 wks later
	Bio-Trek WP	3.0 oz	10 days later
	Heritage	0.2 oz	21 days
4	3336 50 WP	4 oz	14	0.25	0.00	0.00
5	Spectro 90 WDG	8 oz	14	0.00	0.00	0.00
6	WAC 75	5 oz	14	0.25	0.00	0.00
7	WAC 76	5.3 oz	14	0.00	0.00	0.00
8	Thalonil 90 DF	3.5 oz	7	0.00	0.00	0.00
9	TRA-0232	3.5 oz	7	0.25	0.00	0.75
10	Thalonil 90 DF	3.5 oz	14	0.00	0.00	0.00
11	TRA-0232	3.5 oz	14	0.25	0.25	0.25
12	BAS 500 2.09 EC	0.42 fl oz	14	0.50	0.25	0.25
13	BAS 505 DF	0.21 oz	14	1.00	0.25	0.00
14	CGA 279202 50 WG	0.1 oz	14	0.25	0.25	0.50
15	CGA 279202 50 WG	0.15 oz	14	0.00	0.00	0.50
16	CGA 279202 50 WG	0.1 oz	14	0.50	0.50	0.25
	+ Banner MAXX	1 fl oz
17	Chipco 26 GT 2 SC	4 fl oz	14	1.00	0.00	0.25
18	EXP 10830A 4.17 SC*	0.3 fl oz	14	0.50	1.75	0.50
19	EXP 10830A 4.17 SC*	0.6 fl oz	14	0.00	0.00	0.25
20	EXP 10830A 4.17 SC*	1 fl oz	14	0.00	0.00	0.00
21	Chipco Triton 1.67 SC (=80318)	1 fl oz	14	0.25	1.00	0.25
22	Chipco Triton 1.67 SC	1 fl oz	21	0.75	0.00	0.75
23	Heritage 50 WG	0.2 oz	14	0.50	0.00	0.00
24	Heritage 50 WG	0.2 oz	14	0.00	0.00	0.00
	+Daconil Ultrex	3.8 oz
25	Heritage 50 WG	0.4 oz	28	0.25	0.50	1.50
	ALTERNATE WITH
	Daconil Ultrex	3.8 oz	14
26	Eagle 50 WP	0.6 oz	14	0.25	0.00	0.00
	+ Fore 75 DG	6 oz
27	ZeroTol	0.5 fl oz/80 ft2	7	0.50	1.00	3.00
28	ProStar 50 WP	3 oz	14	0.75	1.0	0.50
29	ProStar 70 WP	2.25 oz	14	0.50	0.00	0.50
30	ProStar 70 WP	1.5 oz	14	0.25	0.00	0.00
	+ Heritage 50 WG	0.2 oz
31	S-8172	4 fl oz	14	0.00	1.50	1.00
32	S-8172	8 fl oz	14	0.00	0.50	0.00
33	S-8206	3.2 fl oz	14	0.75	0.50	0.50
34	S-8206	6.4 fl oz	14	0.00	0.00	0.00
35	AMV 300	1 fl oz	14	0.75	0.25	3.25
36	AMV 300	2 fl oz	14	0.25	0.00	0.00
37	UCC-A1562 20 SC	1 fl oz	14	1.50	1.50	0.50
38	UCC-A1562 20 SC	4 fl oz	14	0.50	1.00	1.50
39	UCC-A1562 20 SC	8 fl oz	14	0.25	0.25	0.25
	Least Significant Differenceb			1.02	0.98	0.93

^aRating Scale: 0 = no disease; 1 = 1-5%; 2 = 5-10%; 3 = 10-25%; 4 = 25-50%; and 5 = >50% of plot diseased.

^bP = 0.05. n = 4 replications.

ISU Horticulture:Publications:1999 Turfgrass Report

College of Agriculture