Control of stripe rust of winter wheat with various foliar fungicides

Authors: Chen, Xianming; Evans, Conrad; LIU, YUMEI - Washington State University

Submitted to: Plant Disease Management Reports
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 2/10/2014
Publication Date: 3/29/2014
Publication URL: http://www.plantmanagementnetwork.org/pub/trial/pdmr/reports/2014/CF023.pdf
Citation: Chen, X., Evans, C.K., Liu, Y. 2014. Control of stripe rust of winter wheat with various foliar fungicides. Plant Disease Management Reports. 8:CF023.

Interpretive Summary: A total of 19 foliar fungicide treatments were tested for their efficacy in control of stripe rust on winter wheat during the 2012-2013 crop season. The experimental field near Pullman, WA was planted with a susceptible winter wheat variety on October 30, 2012. A randomized complete block design experiment with four replications was used including a non-treated check treatment. Fungicides were applied on two dates and crop growth stages depending upon the treatments. Disease severity was assessed from each plot five times during the disease season under the natural infection of stripe rust. Area under the disease progress curve (AUDPC) was calculated for each plot using the five sets of severity data. Relative AUDPC was calculated as percentage of the non-treated control. Grain yield and test weight were measured. Rust severity, relative AUDPC, test weight, and yield data were subjected to analysis of variance and means were compared to determine the difference among the treatments. Stripe rust started early, but developed slowly due to the hot and dry weather conditions, and eventually reached 100% severity at dough stage and caused more than 40% yield loss in the non-treated control plots. All fungicide treatments, but one, significantly reduced rust AUDPC and increased test weight. Except four treatments, all treatments increased grain yield compared to the non-treated control. Some of the treatments provided better control than others. Yield increases of the fungicide applications ranged from 1% to 73%. Some of the new formulations could be registered for control of stripe rust.

Technical Abstract: The study was conducted in a field with Palouse silt loam under natural infection of stripe rust near Pullman, WA. Susceptible ‘PS 279’ winter wheat was seeded in rows spaced 14 in. apart at 60 lb/A (99% germination rate) with a drill planter on 30 Oct 12. Fungicides were applied in 16 gal water/A on different dates and stages depending upon the treatment. The first fungicide application timing at jointing stage (Feeks 5) was done on 20 May when stripe rust was 0-5% severity in the field. The second application was done at boot stage (Feeks 10) on 11 Jun when stripe rust in the plots without first fungicide application reached 8-35% severity. A randomized block design was used with four replications. Disease severity (percentage of diseased foliage per whole plot) was assessed from each plot on 20 May, 10 Jun, 17 Jun (data not shown), 25 Jun, and 3 Jul or on the day of fungicide application and 21, 28, 36, and 44 days after the first fungicide application timing, respectively. Plots were harvested on 5 Aug when kernels had 3-5% kernel moisture and test weight of kernels was measured. Area under disease progress curve (AUDPC) was calculated for each plot using the five sets of severity data. Relative AUDPC (rAUDPC) was calculated as percent of the non-treated control. Rust severity, rAUDPC, test weight, and yield data were subjected to analysis of variance and means were separated by Fisher’s protected LSD test. The first fungicide was applied as stripe rust began to develop and the second application was applied little bit later as the disease reached 8-35% severity in the plots without the first application. Stripe rust reached 100% severity in the non-treated check plots about 44 days after the first application, slower than in the past several years as the weather was hot and dry during the late growing season. All fungicide treatments significantly reduced rust severity compared to the non-treated control at milk stage. The rAUDPC values of all treatments were significantly less than the non-treated control, except the treatment of Topguard 10 fl oz/A at Feeks 10, and there were significant differences among the treatments. Not all treatment with one application at Feeks 10 provided less control than those with two applications at both Feeks 5 and 10. Among all treatments, the treatments of Aproach 3.0 fl oz/A at Feeks 5 followed by Aproach Prima 6.8 fl oz/A at Feeks 10 provided the best control of the disease, but the treatments of Topguard 5 fl oz/A at Feeks 5 followed by Topguard 5 fl oz/A at Feeks 10, A18126 4.76 ozwtpr/A at Feeks 10, and A15457 4.1 fl oz/A plus Tilt 4.0 fl oz/A and Quadris 6.0 fl oz/A at Feeks 10 had the similar control. Among the treatments with only one application of a single fungicide at Feeks 10, A18126 4.67 ozwtpr/A, Aproach Prima 6.8 fl oz/A, Quilt Xcel 10.5 fl oz/A, A18126 2.86 ozwtpr/A, A18993 9 fl oz/A, Aproach Prima 3.4 fl oz/A, Custodia 8.6 fl oz/A, Aproach 6.0 fl oz/A, and Aproach Prima 5.0 fl oz/A provided similar levels of control better than others. All treatments, except Topguard 14 fl/A at Feeks 10, significantly increased test weight compared to the non-treated control. The treatment of A15457 4.1 fl oz/A + Tilt 4.0 fl oz/A + Quadris 6 fl oz/A at Feeks 10 produced the highest test weight, and the test weights of eight other treatments were not significantly different from the highest. Except treatments with Topguard 14 fl oz/A at Feeks 10, Aproach 6.0 fl oz/A at Feeks 10, Aproach Prima 5.0 fl oz/A at Feeks 10, and Bumper 4 fl oz/A at Feeks 10, all other treatments significantly increased yield compared with the non-treated check. The treatments with Aproach 3.0 fl oz/A at Feeks 5 followed by Aproach Prima 6.8 fl oz/A at Feeks 10 and Topguard 5 fl oz/A at Feeks 5 followed by Topguard 5 fl oz/A at Feeks 10 produced the highest yields, increasing by 73.6% and 58.0%, respectively c