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2001 CORN ROOTWORM SOIL INSECTICIDE EVALUATIONS
AGRICULTURAL RESEARCH AND DEVELOPMENT CENTER
MEAD, NEBRASKA

Lance J. Meinke, Jim Brown, Jenny Stebbing, Bill McCormick
Department of Entomology
University of Nebraska
Lincoln, Nebraska 68583-0816

Background Information - AgronomicBackground Information - Entomology
Experimental DesignEnvironmental Conditions at Planting
Environmental Conditions: Aztec ApplicationsRainfall and Irrigation
Experimental Compounds TestedRoot Damage Evaluations

Background Information -Agronomic

Hybrid: Pioneer 33G26
Row Spacing: 30 inches
Planting Date 27 April 2001
Planter: Kinze model 2100, 4 row
Planting Depth: 2 inches
Application Equipment: Granular Insecticides
Planting: Planter mounted cone-belt system
Liquid Insecticides
CO2planter-mounted CO2 pressurized sprayer
Field Preparation: Spring 2001 - disked and harrowed
Herbicides Applied: 9 May 2001: Bicep II Magnum, 2.1 qt./A, pre-emerge
8 June 2001: 0.66 oz Accent, 4 oz Distinct/A
Fertilizer Applied: 150 lb. N/A applied as NH3 April 2001
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: Overall mean number of plants/33.5' ± SEM = 48.72 ± 0.26
Phytotoxicity: There were no significant differences (P > 0.05) among treatment stand count means or among number of abnormal plants/treatment at V2-3 growth stage (Hanway 1997).
Insecticide History: Insecticide free: 1989 - 1992, 1994 - 1996, 1998, 2000
Multiclass soil insecticide trials: 1993, 1997, 1999

Background Information - Entomology

Species Present: Northern corn rootworm, Diabrotica barberi Smith and Lawrence, and western corn rootworm, D. virgifera virgifera LeConte. Initial rootworm egg hatch detected 28 May 2001 (predominantly western corn rootworm)
Root Evaluation: 1-6 (Hills and Peters, 1971) and 0 - 3 (J. Oleson, Iowa State University) root rating scales were used to evaluate larval corn rootworm damage in each treatment. Five roots were evaluated in each treatment and replication. (See Nebguide G92-1108-A and http://www.ent.iastate.edu/pest/rootworm/nodeinjury/nodeinjury.html for rating scale descriptions.)
Root Evaluation Date: 11 July 2001

Experimental Design

Design: Randomized complete block design
Replicated four times
Single row treatments
Row Length: 33.5 feet
Statistical Analysis: Plant Stands, Root Ratings: Standard ANOVA procedures; LSD test was used for mean separation where statistical differences (P less than or equal to 0.05) occurred.

Environmental Conditions at Planting

Air Temperature:26oC
Wind speed:5mph at 5 ft. height
Wind direction:S - SW
Soil temperature 2" depth:22oC
Soil temperature surface:25oC
Soil moisture, 0-3" depth:21.7% water (gravimetric method)
% cloud cover:clear, 0% cloud cover
% relative humidity:not recorded
Residue on surface:10 - 15% of soil surface covered with crop residue; soil very moist, somewhat cloddy

Environmental Conditions: Aztec BD 2.1 applied at cultivation (7 June 01)

Air temperature:28oC
Wind speed:5 - 10 mph at 5 ft. height
Wind direction:NE
Soil temperature 2" depth:25oC
Soil temperature surface:34oC
Soil moisture, 0-3" depth:19.6% water (gravimetric method)
% cloud cover:30% cloud cover
% relative humidity:not recorded
Soil surface condition:10 - 15% of soil surface covered with crop residue

Rainfall and Irrigation

April 3 0.16 inch  
  5 0.04 inch  
  6 0.04 inch  
  10 0.51 inch  
  11 0.79 inch  
  20 0.04 inch  
  21 0.12 inch  
  22 0.59 inch  
  30 0.04 inch  
Total     2.33 inches
May 2 0.24 inch  
  3 1.50 inch  
  4 1.58 inch  
  5 1.02 inch  
  6 0.12 inch  
  12 0.04 inch  
  20 1.73 inch  
  25 0.04 inch  
  30 1.97 inch  
  31 0.12 inch  
Total     8.36 inches
June 1 0.04 inch  
  3 0.20 inch  
  4 0.16 inch  
  5 0.24 inch  
  10 0.08 inch  
  13 0.04 inch  
  14 0.67 inch  
  19 0.16 inch  
  20 0.04 inch  
Total     1.63 inches
July 3 0.59 inch  
  11 0.08 inch  
  19 0.08 inch  
  27 0.04 inch  
Total     0.79 inches
August 14 0.12 inch  
  15 1.30 inch  
  24 0.95 inch  
Total     2.37

Irrigation 2001:
Irrigation was applied periodically between planting and root damage evaluation.
June 27 0.5 inch  
  29 0.5 inch  
July 2 1.0 inch  
  6 1.0 inch  
  13 1.0 inch  
  18 1.0 inch  
  23 1.0 inch  
  30 1.0 inch  
August 3 1.0 inch  

Experimental Formulations/Applications Evaluated - 2001

CompoundCompany
Capture 1.15GFMC

Root Damage Evaluation

Insecticide Rate/Placementa
oz ai/1000 ft.		 Mean Root Damage Rating b
  (1-6 scale)(0 - 3 scale)
   
Aztec 4.67G 0.14 I smartbox appl. 2.10 a 0.09 a
Aztec 4.67G 0.14 TB smartbox appl. 2.10 a 0.08 a
Force 3G 0.12 TB 2.10 a 0.10 a
Aztec BD 2.1G 0.141 I 2.15 a 0.10 a
Aztec BD 2.1G 0.141 C 2.30 ab 0.13 a
Regent 4SC see footnote c 2.30 ab 0.16 ab
Force 3G 0.12 I 2.35 a-c 0.18 a-c
Aztec BD 2.1G 0.141 TB 2.40 a-c 0.21 a-d
Capture 2EC see footnote d 2.40 a-c 0.19 a-c
Capture 2EC see footnote e 2.45 a-c 0.24 a-d
Lorsban 15G 1.2 TB 2.45 a-c 0.23 a-d
Counter 20CR 1.2 TB 2.50 a-c 0.18 a-c
Regent 4SC see footnote f 2.55 a-c 0.17 ab
Fortress 5G 0.15 I smartbox appl. 2.75 b-d 0.40 a-e
Capture 1.15G 0.09 TB 2.75 b-d 0.26 a-d
Fortress 5G 0.15 TB smartbox appl. 2.75 b-d 0.39 a-e
Counter 20CR 1.2 I 2.85 c-e 0.34 a-d
Lorsban 15G 1.2 I 2.85 c-e 0.48 b-f
Thimet 20G 1.2 TB 3.10 d-f 0.70 ef
Capture 1.15G 0.09 I 3.15 d-f 0.50 c-f
Untreated   3.30 ef 0.54 d-f
Untreated   3.50 f 0.77 f

a placement:
TB = T-band, 7-inch band placed over the open seed furrow
I = Placed in the open seed furrow
C = first cultivation application on 7 June 2001

bRoot rating scales used: 1 - 6 scale (Hills and Peters 1971); 0 - 3 scale (J. Oleson, Iowa State University); 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).

cRegent 4SC: rate: 0.13 lb ai/A; volume: 4 gallons 10-34-0 fertilizer/A through microtube into open seed furrow

dCapture 2EC: rate: 0.075 oz ai/1000'; volume: 5 gallon water/A, TB application.

eCapture 2EC: rate: 0.075 oz ai/1000'; volume: 2 gallon water/A through microtube into open seed furrow.

fRegent 4SC: rate: 0.13 lb ai/A; volume: 1 gallon water/A through microtube into open seed furrow.

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