1998 Iowa Turfgrass Research Report
Evaluation of Fungicides for Control of Pythium Blight in Perennial Ryegrass - 1997
Mark L. Gleason
Trials were conducted on a perennial ryegrass fairway at Veenker Memorial Golf Course in Ames, IA. Fungicides were applied with a modified bicycle sprayer at 30 psi and a dilution rate of 5 gal/1,000 ft2. Experimental design was a randomized complete block with 4- x 5-ft subplots and 4 replications per treatment. All treatments began on June 13, when active Pythium mycelium was noted in the grass. Additional applications were made on June 20 and 27 and July 4, 11, 18, and 25.
Weather during late June, and again in late July, was moderately conducive to Pythium blight (daytime temperatures 80-95° F, nights 70-80° F, prolonged periods of high relative humidity). Disease development in the untreated check plots was light on both rating dates (July 24 and 31). Most treatments showed no symptoms, and had significantly less disease than the check treatment.
No symptoms of phytoptoxicity were observed during the course of the study.
Table 1. 1997 Pythium Blight Trial. Perennial ryegrass fairway at Iowa State University's Veenker Memorial Golf Course, Ames, Iowa. Plot size = 20 ft2, 4 plots/trt; 80 ft2 per treatment
Interval
Number of infection centers per
plot1
Trt.
Product
Rate/1000 ft2
(days)
July 24
July 31
1
Check
-----
----
2.0
1.8
2
Heritage 50 WG
0.4 oz
14
0.0
0.0
3
Heritage 50 WG
0.3 oz
14
0.0
0.0
4
Heritage 50 WG
0.2 oz
14
0.0
0.3
5
Terrazole 35 W
2.0 oz
7
0.0
0.0
6
Terrazole 35 W
4.0 oz
7
0.0
0.8
7
Terrazole 35 W
6.0 oz
7
0.0
0.0
8
Confidential 1
-----
----
0.3
0.0
9
Confidential 2
-----
----
1.0
0.0
10
Confidential 3
-----
----
1.3
2.5
11
Confidential 4
-----
----
0.0
1.0
12
Confidential 5
-----
----
0.0
0.0
13
Heritage 50 WG
600 g ai/ha
10
0.0
0.0
14
Aliette 80 WP
9,765 g ai/ha
10
0.0
0.0
LSD2
1.01
1.60
1n = 3.
2Least significant difference
(P = 0.05).
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ISU Horticulture:Publications:1998 Turfgrass Report | College of Agriculture |