Objective:

To evaluate the effects of fungicides and application timing on stripe rust control in spring wheat. 

Results:

The efficacy of three fungicides were evaluated for the control of stripe rust in spring wheat. Fungicides were applied at the three tiller (3T) stage on June 5th, and at early boot (EB) on June 17th, or sequentially at 3T and EB (Table 2). The experimental design was a randomized complete block with three replications.

Stripe rust infection level was low, with the non-treated check experiencing 30% infection. As a result, no significant differences in stripe rust control were detected among the treatments. Nevertheless, significant differences were observed for yield. Prosaro applied at 6.5 fl oz/A at EB afforded the greatest yield at 77.8 bu/A, which was significantly greater than the non-treated check at 56.2 bu/A. All other treatments produced yields equivalent to the non-treated check.

Summary:

Dry weather conditions kept stripe rust infection levels low and prevented an accurate determination of fungicide efficacy.

Table 1. Materials and Methods.

Seeding Date: 5/6/2015 Harvest Date: 8/11/2015
Julian Date: 126 Julian Date: 223
Seeding Rate: 110 lbs/A Soil Type:  Creston SiL
Previous Crop: Spring Wheat Soil Test: 431-40-258
Tillage: Conventional Fertilizer: 0-30-0
Irrigation: None Herbicide: Huskie Complete 13.7 oz/A

Table 2. Efficacy of fungicide application rate and timing in the control of stripe rust in spring wheat.

Treatment Rate Timing SR % LOD % YLD bu/A1 PRO %2 TWT %1
Check 30.0 0.0 56.2 12.7 60.8
Stratego
Induce 90 SL		 4 floz/A
0.13% v/v		 3T 19.3 0.0 65.5 12.5 61.2
Prosaro 421 SC
Induce 90 SL		 5 floz/A
0.13% v/v		 EB 2.7 0.0 64.2 12.9 61.3
Prosaro 421 SC
Induce 90 SL		 6.5 floz/A
0.13% v/v		 EB 2.7 0.0 77.8 13.5 62.1
Stratego
Induce 90 SL
Prosaro 421 SC
Induce 90 SL		 4 floz/A
0.13% v/v
6.5 floz/A
0.13% v/v		 3T

EB		 2.3 0.0 60.9 12.8 61.4
Headline 6 floz/A EB 3.7 0.0 69.8 13.2 61.7
Mean 10.1 0.0 65.7 12.9 61.4
CV 193.4 0.0 9.2 5.3 1.4
LSD ns ns 11.0 ns ns
Pr>F 0.4235 1.000 0.0201 0.5648 0.5757

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

3T = 3 tiller on June 5; EB: early boot on June 17