2006 CORN ROOTWORM EFFICACY TRIAL

 YIELDGARD ROOTWORM COMPARISON TO SOIL INSECTICIDES AND SEED TREATMENTS¹

Final Report

University of Nebraska

Agricultural Research and Development Center

Mead, Nebraska

Lance J. Meinke, Jim Brown,

 Laura Campbell, Bill McCormick

Department of Entomology

University of Nebraska

Lincoln, Nebraska 68583-0816

¹ The data presented in this report are not to be released to the public without the written

   permission of the Department of Entomology, University of Nebraska, Lincoln, Nebraska.

Background information pertaining to the experiment conducted at the ARDC, near Mead, Nebraska during 2006.

Agronomic

            Hybrids:                                    DKC 60-17, DKC 60-13

            Row Spacing:                           30 inches

            Planting Date:                           27 April 2006

            Planter:                                     Kinze model 2100, 4 row cone

            Planting Depth:                         2 inches

            Application Equipment:            Granular insecticide

                                                              Planting: planter mounted cone-belt system

                                                            Liquid insecticide

                                                              Planter mounted CO₂ pressurized sprayer

            Field Preparation:                     10 March 2006 - chopped and disked, 18 April 2006 - disked

            Herbicides Applied:                  28 April 2006: Cintch ATZ, 2.6qt/ac, pre emerge

                                                              5 June 2006: Spirit 1.0 oz/ac

            Fertilizer Applied:                     150 lb. N per acre applied as NH_3, 13 April 2006 

            Previous Crop:                          Continuous corn (trap crop)

            Soil Information: 

                  Type:                                  Silty clay loam 

                  Ph:                                              6.4 

                  CEC:                                        29.4                                 

                  % organic matter:                        2.8 

                  % clay:                                      29.05 

                  % silt:                                        66.67                               

                  % sand:                                       4.28 

            Plant Population:                 There were no significant differences (P > 0.05) among treatment stand count means at V3-V4 growth                                                                     stage (Hanway 1997). The overall mean number of plants per 33.5 ft + SEM = 41.9 + 0.4

            Insecticide History:                   Insecticide free: 1999, 2001, 2003, 2005

                                                               Multiclass soil insecticide trials: 1998, 2000, 2002, 2004

Entomological

Species present:                 Northern corn rootworm, Diabrotica barberi Smith and

Lawrence, and western corn rootworm, D. virgifera virgifera LeConte. Initial rootworm egg hatch occurred between 27-29 May 2006 (predominantly western corn rootworm).

Root Evaluation:                  0-3 root rating scale (Oleson et al. 2005) was used to evaluate larval corn rootworm damage in each treatment. Five roots per replication were evaluated in each treatment.

Root Evaluation Date:          12 July 2006

Experimental Design

            Design:                                   Randomized complete block design

                                                                    Replicated four times

                                                                    Single-row treatments

            Row Length:                            33.5 feet

            Statistical Analysis:                  Root ratings, stand: Used SAS Mixed Procedure; Protected LSD

test was used for mean separation (P ≤ 0.05) .

Environmental

            Conditions at planting:

                  Air temperature:                               26°C

                  Wind speed:                                     10 mph at 5 ft height

                  Wind direction:                                 W

                  Soil temperature 2" depth:                19°C

                  Soil temperature surface:                  29°C

                  Soil moisture, 0-3" depth:                 not recorded

                  % cloud cover:                                 25 % cloud cover

                  % relative humidity:                          not recorded

                  Residue on surface:                          30% of soil surface covered with crop residue; soil

moist, some clods on surface

Rainfall

Irrigation (through August 2006):

Sprinkler irrigation was applied as needed throughout the season.

June       1   1.00 inches                                       August 04 1.5 inches

15  1.0                                       

            30  2.0

July        7  1.0 inches

26  1.25

Table 1. 2006 Corn Rootworm Soil Insecticide Experiment 1.

University of Nebraska Agricultural Research and Development Center, near Mead, NE

Root Damage Evaluation

^a Rate presented as oz ai per 1000 row ft except where other units listed:

            TB = T-band, 7-inch band placed over the open seed furrow;

             I = placed in the open seed furrow;

            ST = seed treatment.

            A14974 250 CS is a liquid formulation of tefluthrin

^b Root rating scale used: 0 - 3 scale (Oleson et al. 2005); within columns, mean root rating values

  followed by the same letter are not significantly different from each other (Fisher’s protected LSD test

 @ 0.05 significance level). No plant lodging was observed in any treatment on 10 July 2006.