Objective:

To evaluate application timings and rates of Headline for the control of stripe rust in winter wheat.   

Results:

Headline was applied to Decade winter wheat at two rates (6 and 9 fl oz/A) and two growth stages (two tiller and flag leaf), either as single or sequential applications on May 1 and May 20, respectively (Table 2). The application of Headline resulted in significant differences for percent stripe rust infection, yield, and test weight. Stripe rust infection averaged 25.2%, and ranged from 7.7% to 61.7 percent. Most treatments afforded commercially acceptable control. However, the 6 oz/A rate applied at the two tiller stage of growth produced infection levels comparable to the non-treated check. In turn, yields were statistically equivalent between these two treatments.

An analysis was performed to evaluate the economic feasibility of sequential fungicide applications. The highest adjusted gross return ($497.20) was obtained with 9 oz/A applied as a single application at flag leaf (Table 3). Conversely, the least profitable fungicide treatment ($413.50) was 9 oz/A applied sequentially. This occurred despite having the highest level of stripe rust control. In short, there was not a direct relationship between stripe rust control and profitability.

Further, there was not a direct relationship between yield and profitability. Although the sequential application at 6 fl oz/A afforded the highest yield at 109.9 bu/A, the adjusted gross return was $495.60 per acre. The benefit of making two applications at the 6 fl oz/A rate compared to a single application at flag leaf was $4.70. In comparison the financial loss of sequential applications at the 9 fl oz/A compared to the single application at flag leaf was $83.70/A.

Summary: 

Headline was effective at controlling stripe rust and the most economical application timing was at flag leaf at 9 fl oz/A. 

Table 1. Materials and Methods

Seeding Date: 9/29/2014 Harvest Date: 7/28/2015
Julian Date: 272 Julian Date: 209
Seeding Rate: 80 lb/A Soil Type: Creston SiL
Previous Crop: Canola Soil Test: 29-10-158
Tillage: Conventional Fertilizer: 9-40-70, 130-0-0 TD
Irrigation: None Herbicide: Huskie 11 oz/A

Table 2. Effect of Headline on agronomic performance of winter wheat, Kalispell, MT - 2015.

Application Timing Rate
fl oz/A		 HD
Julian		 SR
%		 LOD
%		 YLD 
bu/A1		 PRO
%2		 TWT
lb/bu1
Two Tillers + Flag Leaf 9 153.0 7.7 0.0 97.9 10.2 61.6
Two Tillers + Flag Leaf 6 153.3 10.7 0.0 109.9 9.8 62.1
Flag Leaf 9 153.7 10.7 0.0 107.0 10.1 61.3
Flag Leaf 6 153.0 15.0 0.0 103.6 10.1 61.7
Two Tillers 9 153.0 24.3 0.0 96.5 9.7 60.9
Two Tillers 6 153.3 46.7 0.0 88.2 9.5 60.9
Check 152.7 61.7 2.7 78.8 938 59.7
Mean 153.1 25.2 0.4 97.4 9.9 61.1
CV 0.5 63.4 375.6 10.2 3.5 1.3
LSD ns 28.5 ns 17.7 ns 1.4
Pr>F 0.7783 0.0079 0.2622 0.0269 0.2849 0.0380

HD: heading date; SR: stripe rust; LOD: lodging; YLD: yield; PRO: protein; TWT: test weight; ns: non-significant

1 adjusted to 13% moisture

2 adjusted to 12% moisture

Table 3. Economic analysis for the application of Headline fungicide to winter wheat for stripe rust control.

Application
timing		 Rate
fl oz/A		 YLD
bu/A		 Gross Return
$5.00/bu		 Headline Cost/A
$3.67/oz		 Application Cost/A
$5.00		 Adjusted Gross Return
$/Acre
Flag Leaf 9 107.0 535.20 33.00 5.00 497.20
Two Tillers + Flag Leaf 6 109.9 549.60 44.00 10.00 495.60
Flag Leaf 6 103.6 517.90 22.00 5.00 490.90
Two Tillers 9 96.5 482.30 33.00 5.00 444.30
Two Tillers 6 88.2 441.00 22.00 5.00 414.00
Two Tillers + Flag Leaf 9 97.9 489.60 66.10 10.00 413.50
Check 78.8 393.90 0.00 0.00 393.90
Mean 97.4 487.07 . . 449.90
CV 10.2 10.2 . . 11.1
LSD 17.7 88.4 . . 88.4
Pr>F 0.0269 0.0269 . . 0.0942

YLD: yield