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�Alsen� HRSW Response to AMS 21619 Fungicide Rate

 

S. Halley, Langdon Research Extension Center-North Dakota State University, Box 310 Hwy 5 E Langdon, North Dakota 58249

*Corresponding author PH: (701) 256-2582, E-mail: shalley@ndsuext.nodak.edu

 

OBJECTIVES

 

To determine the effectiveness of rate on efficacy of fungicide, AMS21619 (Bayer experimental), applied to �Alsen� HRSW.

 

Introduction

 

A new fungicide AMS 21619, prothioconazole, has shown improved efficacy in the control of Fusarium head blight (FHB) on durum and hard red spring wheat and reductions in DON levels (deoxynivalenol) over most of the currently labeled fungicides on small grains. Research is needed so growers will know the consequences of different rates under different environmental conditions and infections from different causal organisms.

 

MATERIALS AND METHODS

 

Cultivar �Alsen� HRSW was planted for AMS 21619 fungicide rate evaluation in a field at the Langdon Research Extension Center in spring 2002. An area was planted with a Melroe double-disk grain drill, disks spaced 6-inches apart. The area was divided to plots 12 ft. wide by 20 ft. long in a RCB design with six replicates. Recommended production practices for Northeast North Dakota were followed. Three weeks prior to heading a Fusarium spawn grown on spring wheat was hand broadcast at a rate of approximately 200 grams/plot.

 

AMS 21619 rates were:

1.      Untreated

2.      0.125 X (0.7 fl. oz/acre)

3.      0.25 X (1.4 fl. oz/acre)

4.      0.5 X (2.85 fl. oz/acre)

5.      1 X (5.7 fl. oz/acre)

6.      2 X (11.4 fl. oz/acre)

7.      3 X (22.8 fl. oz/acre)

 

Treatments were applied by a modified SPRAYAIR� tractor sprayer. The sprayer was modified to distribute the solution from orifices angled 30 degrees downward from horizontal oriented forward and backward to maximize spike coverage. The solution carrier was CO2 delivering volume of 19.2 gpa into the air stream. The tractor traveled on the left half of the plot area. This area also provided border to reduce off target drift between treatment areas. Visual estimation of FHB incidence and field severity, 20 samples per plot, (spikelet count per individual head multiplied times FHB infected spikes per head) and flag leaf necrosis, 3 samples per plot, were determined 20 days after fungicide application. A flag leaf necrosis sample was one leaf and a head sample was one spike. Each plot was harvested with a Hege plot combine and the grain sample cleaned and processed for yield and test weight measurement. Data was analyzed with the general linear model (GLM) in SAS. Least significant differences (LSD) were used to compare means at the 5% probability level.

 

RESULTS AND DISCUSSION

 

Reduction in incidence of FHB was quite linear with rate. Rates less than recommended 1X rate were not different. Two and three X rates significantly reduced FGB incidence. FHB field severity was similar. Rates greater than 0.5X maximized FHB field severity reductions although 0.5X was not different from 1X rate. All rates except 0.125X rates and untreated were equal for flag leaf necrosis. Leaf disease levels were considerably less than most years in the Langdon area, researcher�s observation. Yields were also linear with rate, increasing as fungicide rate increased. One X, 2X, and 3X rates had the same yields, significantly greater than untreated (10-14 bu/acre). Test weight also increased as fungicide rate increased.

 

AMS 21619

FHB

Flag Leaf

Yield

Test

Rate

Incidence

Severity

Necrosis

 

Weight

 

%

%

%

bu/acre

lb/bu

 

 

 

 

 

 

Untreated

72.5 a

15.3 a

35.5 a

45.3 a

57.3 a

 

 

 

 

 

 

0.125  X

77.4 a

15.2 a

22.2 b

49.3 b

57.7 a

0.25  X

70.0 a

  10.0 ab

  11.6 bc

  52.2 bc

58.3 b

0.5 X

  63.3 ab

13.8 a

  4.2 c

  52.8 bc

58.4 b

 

 

 

 

 

 

1 X

52.5 b

    5.7 bc

  4.5 c

  55.7 cd

  58.8 bc

2 X

30.0 c

  3.9 c

  4.8 c

57.3 d

  59.1 cd

3 X

22.5 c

  1.4 c

  2.4 c

59.1 d

59.7 d

 

 

 

 

 

 

LSD P>0.05

14.2

5.4

12.8

3.9

0.7

% C.V.

22

49

89

6

1

 

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