1998 Iowa Turfgrass Research Report
1997 Preemergence Annual Weed Control Study
Barbara R. Bingaman, Nick E. Christians, and Michael B. Faust
The objective of this study was to screen various preemergent (PRE) and postemergent (POST) herbicides for their efficacy in controlling annual weeds in turfgrass. The study was conducted at the Iowa State University Horticulture Research Station north of Ames, IA. The experimental plot was in 'common' Kentucky bluegrass. The soil in this area was a Nicollet (fine-loamy, mixed, mesic Aquic Hapludoll) with 2.4% organic matter, a pH of 6.5, 7 ppm P, and 97 ppm K.
The experiment was arranged in a randomized complete block design. Individual plots were 5 x 5 ft with three replications. There were 38 treatments including an untreated control (Table 1). Eleven of the treatments were screened in combination with methylene urea (39-0-0). Barricade 65WG, Pendimethalin 60WDG, and Dimension 1EC were screened at various rates in single preemergent (PRE) and split PRE and postemergent (POST) applications in combination with fertilizer. Three granular Dimension plus fertilizer formulations (AND444, AND445, and AND442) and a fertilized control also were included. Turf that received treatments two through twelve was given an equivalent amount of nitrogen at the time of both PRE and POST applications.
Three granular herbicides from The Scotts Company (S-7135, S-6619, and S-2452) were included. These materials were applied in single PRE and split PRE plus POST treatments. Preclaim 3.09EC was screened as an early-post and mid-postemergence material at two different rates for AgrEvo. Acclaim Extra 0.57EW also was included as an early-postemergence treatment and Pendimethalin 60WDG was applied as a PRE material. An experimental formulation from Rhone-Poulenc, MY-100, was applied as a PRE treatment at three different rates. Barricade 65WG was screened at various rates in single PRE and in split PRE and POST applications for Novartis. In addition, Pendimethalin and Dimension 1EC were applied in single PRE and split PRE and POST treatments. Ronstar 2G was screened as a PRE material.
Granular formulations were applied using 'shaker dispensers'. Liquids were applied at 30 psi using a CO2 backpack sprayer equipped with TeeJet™ #8006 flat fan nozzles. Preemergent (PRE) treatments were made on May 1. Crabgrass germination was noted on June 7. This was considerably later than usual for this location. Sequential applications of treatments 2 - 12 were made on July 3, 60 days after the initial application (Table 1). Postemergent applications of treatments 14, 16, and 18 were made on June 18, six to eight weeks after the initials. Early-postemergence applications of treatments 19, 20, and 23 were made on June 11 when the crabgrass was in the 1- to 4-leaf stage. Mid-postemergence applications of treatments 21 and 22 were made on July 10 when the crabgrass had one to three tillers. Postemergent applications of treatments 35 - 38 were made on July 3, 60 days after the initial application.
Visual turf quality data were taken May 12 through August 20 (Tables 2 and 3). Visual quality was assessed using a 9 to 1 scale: 9 = best, 6 = lowest acceptable, and 1 = worst turf quality. Crabgrass control was reported as the percentage of area per plot covered by crabgrass. Crabgrass data were taken on July 2, July 10, July 15, July 30, and August 20 (Table 4). In addition, these data were converted to express percentage reduction in crabgrass cover as compared with the untreated control (Table 5).
All data were analyzed with the Statistical Analysis System (SAS, Version 6.10) and the Analysis of Variance (ANOVA) procedure. Fisher's Least Significant Difference (LSD) test was used to compare visual quality and crabgrass control means.
Turf that received the herbicide plus methylene urea treatments (Barricade 65WG, Pendimethalin 60WDG, and Dimension 1EC), the 'AND' Dimension plus fertilizer formulations (AND444, AND445, and AND442), and the fertilized control had significantly better quality than the untreated control and turf treated with the other herbicides for the entire season (Tables 2 and 3). Bluegrass treated with the other materials exhibited quality similar to the untreated control.
Throughout the season on each data collection date, at least 36 of the herbicides significantly reduced crabgrass cover when compared with the untreated control (Table 4). Crabgrass cover reductions „ 90% (when compared with the untreated control) were reported in turf treated with 20 herbicides on July 2, 23 on July 10, and 15 on July 15 (Table 5). By August 20, only 11 materials produced crabgrass reductions at this same level. Seven treatments produced reductions „ 90% for the entire season.
Table 1. Materials, rates, and application dates for herbicides and fertilizers used in the 1997 Pre- & Postemergence Annual Weed Control Study.
|
|
|
(PRE)2 |
|
45-60 DAT (POST)2 |
||
|
|
Materials |
lb a.i./A. |
(39-0-0) |
|
lb a.i./A. |
(39-0-0) |
|
1 |
Untreated control |
NA |
NA |
|
NA |
NA |
|
2 |
Barricade 65WG1 |
0.650 |
45.20 g |
|
none |
45.20 g |
|
3 |
Pendimethalin 60WDG1 |
1.500 |
45.20 g |
|
none |
45.20 g |
|
4 |
Dimension 1EC1 |
0.250 |
45.20 g |
|
none |
45.20 g |
|
5 |
Dimension 1EC1 |
0.380 |
45.20 g |
|
none |
45.20 g |
|
6 |
Dimension 1EC1 |
0.125 |
45.20 g |
|
0.125 |
45.20 g |
|
7 |
Dimension 1EC1 |
0.250 |
45.20 g |
|
0.125 |
45.20 g |
|
8 |
AND444 Dimension FG 0.072 + fertilizer1 |
0.125 |
none |
|
none |
45.20 g |
|
9 |
AND445 Dimension FG 0.164 + fertilizer1 |
0.250 |
5.52 g |
|
none |
45.20 g |
|
10 |
AND442 Dimension FG 0.035 + fertilizer1 |
0.060 |
0.57 g |
|
0.060 |
0.57 g |
|
11 |
AND444 Dimension FG 0.072 + fertilizer1 |
0.125 |
none |
|
0.125 |
none |
|
12 |
Fertilized control1 |
NA |
45.20 g |
|
NA |
45.20 g |
|
|
|
Initial Application |
|
Sequential Application |
|
|
|
Rate |
|
Rate |
|
13 |
S-71353 |
1.19 |
|
none |
|
14 |
S-71353 |
1.19 |
|
1.19 |
|
15 |
S-66193 |
1.14 |
|
none |
|
16 |
S-66193 |
1.14 |
|
1.14 |
|
17 |
S-24523 |
0.92 |
|
none |
|
18 |
S-24523 |
0.92 |
|
0.92 |
|
|
Materials |
Rate |
Timing of applications6 |
|
19 |
Preclaim 3.09 EC5 |
1.54 |
EARLY POST |
|
20 |
Preclaim 3.09 EC5 |
2.06 |
EARLY POST |
|
21 |
Preclaim 3.09 EC5 |
2.06 |
MID POST |
|
22 |
Preclaim 3.09 EC5 |
3.09 |
MID POST |
|
23 |
Acclaim Extra 0.57 EW5 |
0.06 |
EARLY POST |
|
24 |
Pendimethalin 60WDG5 & 7 |
1.50 |
PRE |
|
|
|
product/ |
Timing of applications8 |
|
25 |
MY - 100 (30% SC)7 |
3.00 |
PRE |
|
26 |
MY - 100 (30% SC)7 |
4.50 |
PRE |
|
27 |
MY - 100 (30% SC)7 |
6.00 |
PRE |
|
|
|
Initial Application |
Sequential Application |
|
|
|
Rate |
Rate |
|
28 |
Barricade 65WG10 |
0.32 |
none |
|
29 |
Barricade 65WG10 |
0.38 |
none |
|
30 |
Barricade 65WG10 |
0.48 |
none |
|
31 |
Barricade 65WG10 |
0.65 |
none |
|
32 |
Pendimethalin 60WDG10&11 |
1.50 |
none |
|
33 |
Ronstar 2G10 |
2.00 |
none |
|
34 |
Dimension 1EC10 |
0.25 |
none |
|
35 |
Barricade 65WG10 |
0.25 |
0.25 |
|
36 |
Barricade 65WG10 |
0.33 |
0.17 |
|
37 |
Pendimethalin 60WDG10&11 |
0.75 |
0.75 |
|
38 |
Dimension 1EC10 |
0.125 |
0.125 |
1These materials were screened for Rohm & Haas. Methylene urea (39-0-0) was the nitrogen source in the 'AND' materials and was used as the fertilizer blank. Fertilizers were applied at 4 lb product/1000 ft2 for each of 2 applications.
2Initial applications (PRE) were made on May 1 before crabgrass germination and POST applications were applied 45 to 60 days later on June 30.
3These products were screened for The Scotts Company.
4PRE applications were made on May 1 before crabgrass emergence and POST applications were made 6 - 8 weeks later on June 18.
5These materials were screened for AgrEvo.
6PRE applications were made on May 1 before crabgrass germination, EARLY POST on June 11 when the crabgrass was in the 1- to 4-leaf stage, and MID POST on July 10 when the crabgrass had 1 to 3 tillers.
7These materials were screened for Rhone-Poulenc Ag Company.
8PRE applications were made on May 1 before crabgrass germination.
9PRE applications were made on May 1 before crabgrass germination and Post were made 60 days later on July 3.
10These materials were screened for Novartis.
11Pendimethalin 60WDG was substituted for Pendulum 60DG.
PRE applications were made on May 1 (treatments 1-18, 24-27, and 28-38). Crabgrass germination was on June 7.
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ISU Horticulture:Publications:1998 Turfgrass Report | College of Agriculture |