TITLE:

Peanut Tolerance to Outlook and Dual Magnum applied PPI, PRE, AT-CRACK, and POST at AG-CARES, Lamesa, TX in 2002.

AUTHORS:

Peter Dotray, Wayne Keeling, Trent Murphree, John Everitt, Associate Professor, Professor, Graduate Research Assistant, Research Associate

MATERIALS AND METHODS:

             Plot Size:                        4 rows by 50', 3 replications

             Soil Type:                      Amarillo fine sandy loam

             Planting Date:                May 2, 2002

             Variety:                          Flavor Runner 458

             Application Dates:         PPI - April 11 and incorporated with spring tooth harrow

                                                    PRE - May 2

                                                    At-Crack - May 13

                                                    Post - May 30

             Rainfall in-season;         4.9 inches

             Irrigation in-season:       15.5 inches

             Digging Date:                October 10

             Harvest Date:                 October 16

RESULTS AND DISCUSSION:

Weed control is critical to peanut production on the Texas High Plains. Chloroacetamide herbicides, such as Dual Magnum, Lasso, and Outlook, have good activity on annual grasses, small-seeded broadleaf weeds, and yellow nutsedge. Growers, however, have expressed concern regarding the injury potential of these soil applied herbicides. In light of the recent injury observed from Strongarm applied to the soil, this study was designed to examine peanut tolerance to the newest chloroacetamide herbicide, Outlook, when applied preplant incorporated (PPI), preemergence (PRE), at ground cracking (AT-CRACK), and postemergence (POST). At each application timing, Dual Magnum was applied for comparison purposes. All plots were kept weed-free.

At all rating dates in May through July, Outlook PRE at 0.75 and 0.84 lb/A injured peanut. Peanut injury was 20% in May, but decreased to 3% in July. Slight injury (2 to 5%) from PPI applications were observed in June and July. No injury was observed following any AT-CRACK or POST application. By September, no visual injury was observed following any treatment. A decrease in peanut yield was observed following Outlook PRE at 0.75 and 0.84 lb/A.