TITLE:
Peanut Tolerance to Strongarm Applied Postemergence at AG-CARES, Lamesa, TX 2001.
AUTHORS:
Peter Dotray, Jarred Karnei, Wayne Keeling, Associate Professor, Graduate Research Assistant, Professor
MATERIALS AND METHODS:
Plot Size: 4 rows by 35 ft.
Soil Type: Amarillo fine sandy loam
Planting Date: May 1, 2001
Variety: Flavor Runner 458
Irrigation: Preplant 2.75"; In-season 18.45"
Application Dates: Early postemergence - May 18, 2001
Mid postemergence - June 14, 2001
Harvest Date: October 31, 2001
RESULTS AND DISCUSSION:
Strongarm received a full registration label before the 2000 growing season. Research prior to registration indicated that Strongarm had good activity on pigweed, devil’s-claw, morningglory, and nutsedges. In addition, good crop tolerance was reported. During its launch year in 2000, significant peanut injury was observed from many preplant incorporated and preemergence treatments. Injury came in the form of stand loss and/or chlorosis and necrosis. A supplemental label was issued for Texas, Oklahoma, and New Mexico in 2001 restricting Strongarm use on soils with a pH of 7.2 or greater, which is most of West Texas. This study was established to evaluate peanut tolerance to Strongarm applied postemergence. Strongarm was applied at 0.047, 0.032, 0.016, and 0.008 lb ai/A early postemergence and mid postemergence. Cadre at 0.063 was applied at each timing for comparison purposes. All treatments contained a non-ionic surfactant at 0.25% v/v. All plots were maintained weed-free to accurately assess herbicide injury.
No peanut injury was observed from any Strongarm rate or timing. No reduction in peanut height or width was observed. Peanut yield ranged from 3620 to 4210 lb/A, but was not affected by any Strongarm application. Similar results were reported at the Western Peanut Growers farm near Denver City, where this experiment was repeated. These results indicate that Flavor Runner 458 has excellent tolerance to Strongarm applied postemergence. Additional tolerance and weed control studies are needed to support a Strongarm postemergence label; however, at the current time, Strongarm use in peanut is restricted to preplant incorporated and preemergence applications, with the previously mentioned soil pH resistrictions.
|
Table 1. Peanut injury, height, width, and yield as affected by Strongarm and Cadre applied postemergence. |
|||||||||
|
|
|
|
Peanut Injury |
Peanut Ht |
Peanut Wd |
Yield |
|||
|
Treatment |
Rate |
Timing* |
6-1 |
6-28 |
7-26 |
8-30 |
8-30 |
8-30 |
10-31 |
|
|
(lb/A) |
|
--------------%-------------- |
-----------inches----------- |
lb/A |
||||
|
Strongarm |
0.008 |
EP |
0 |
0 |
0 |
0 |
9 |
34 |
4210 |
|
Strongarm |
0.016 |
EP |
0 |
0 |
0 |
0 |
8 |
34 |
3790 |
|
Strongarm |
0.032 |
EP |
0 |
0 |
0 |
0 |
8 |
34 |
4050 |
|
Strongarm |
0.047 |
EP |
0 |
0 |
0 |
0 |
8 |
34 |
3980 |
|
Cadre |
0.063 |
EP |
0 |
0 |
0 |
0 |
8 |
34 |
4080 |
|
Strongarm |
0.008 |
MP |
0 |
0 |
0 |
0 |
8 |
34 |
3620 |
|
Strongarm |
0.016 |
MP |
0 |
0 |
0 |
0 |
8 |
34 |
3880 |
|
Strongarm |
0.032 |
MP |
0 |
0 |
0 |
0 |
9 |
34 |
4120 |
|
Strongarm |
0.047 |
MP |
0 |
0 |
0 |
0 |
8 |
33 |
3690 |
|
Cadre |
0.063 |
MP |
0 |
0 |
0 |
0 |
8 |
34 |
3690 |
|
Non-treated |
0 |
– |
0 |
0 |
0 |
0 |
9 |
34 |
3810 |
|
LSD |
|
|
NS |
NS |
NS |
NS |
0.8 |
0.8 |
620 |
*EP = early postemergence (May 18); MP = mid postemergence (June 14).