Fungicide seed treatments for reducing yield losses caused by stripe rust on spring wheat, 2006

Authors: Chen, Xianming; Wood, David

Submitted to: Scientific and Technical Review
Publication Type: Research Technical Update
Publication Acceptance Date: 3/1/2007
Publication Date: 4/1/2007
Citation: Chen, X., Wood, D.A. 2007. Fungicide seed treatments for reducing yield losses caused by stripe rust on spring wheat, 2006. Plant Disease Management Reports. 1:ST006.

Interpretive Summary: The study was conducted in a field under natural infection of stripe rust near Pullman, WA. Urea (46-0-0) was applied at the time of cultivation. Seed of susceptible ‘Fielder’ spring wheat was treated with Raxil, Dividend Extreme, Apron XL, and various rates of BAS 595XEF combined with Apron XL with or without Charter at 400 ml/100 kg. Non-treated seed served as check. The treated seed was planted with an experimental drill planter on 28 Apr. Harmony Extra 4.16 g plus Buctril with Agridex was applied on 30 May at tillering stage. Stripe rust severity (percent of diseased foliage) was assessed for each plot on 29 Jun at late boot stage; 10 Jul at flowering stage; and 24 Jul at soft dough stage. Plots were harvested on 15 Aug when kernels were naturally dry, and test weight of kernels was measured for each plot. All treatments, except for the treatments of Raxil MD and Apron XL, significantly reduced stripe rust severity compared to the non-treated check at the first note on 29 Jun at late boot stage. At the second note on 10 Jul at flowering stage, all treatments were significantly lower than the non-treated check. At the third note on 24 Jul at soft dough stage, all treatments and the check had 100% of rust severity. All treatments did not significantly increase grain test weight compared to the non-treated check. All treatments increased grain yield by 4.9 to 26.8% compared to the non-treated check. However, the increases by Dividend, Raxil MD, and Apron XL were not significant, while those of the other treatments were significant. The results show that BAS 595XEF can be used to reduce early infection of and grain yield losses caused by stripe rust on spring wheat.

Technical Abstract: The study was conducted in a field with Palous silt loam under natural infection of stripe rust near Pullman, WA. Urea (46-0-0) was applied at 11.3 kg/ha at the time of cultivation. Seed of susceptible 'Fielder' spring wheat was treated with Raxil, Dividend Extreme, Apron XL, and various rates of BAS 595XEF combined with Apron XL at 5.56 ml/100 kg with or without Charter at 400 ml/100 kg. Non-treated seed served as check. The treated seed was planted at 11.3 kg/ha in rows 0.3 m apart with an experimental drill planter on 28 Apr. Harmony Extra 4.16 g plus Buctril 0.17 L/ha with Agridex at 1% of spray volume was applied on 30 May at tillering stage. A randomized block design was used with four replications for each treatment. Stripe rust severity (percent of diseased foliage) was assessed for each plot on 29 Jun at late boot stage; 10 Jul at flowering stage; and 24 Jul at soft dough stage. Plots were individually measured at the time of harvest and plot area ranged from 6.2 to 7.3 m2. Plots were harvested on 15 Aug when kernels were naturally dry, and test weight of kernels was measured for each plot. Area under disease progress curve (AUDPC) was calculated for each plot using the three sets of rust severity data. Relative AUDPC was calculated as percent of the non-treated check. Rust severity, relative AUDPC, test weight, and yield data were subjected to analysis of variance and means were separated by Fishers protected LSD test. Mean severity of stripe rust in non-treated check plots was 42.5, 100.0, and 100.0% on 29 Jun, 10 Jul, and 24 Jul, respectively. All treatments, except for the treatments of Raxil MD and Apron XL, significantly reduced stripe rust severity compared to the non-treated check at the first note on 29 Jun at late boot stage. At the second note on 10 Jul at flowering stage, all treatments were significantly lower than the non-treated check. At the third note on 24 Jul at soft dough stage, all treatments and the check had 100% of rust severity. AUDPC values of all fungicide treatments were significantly different from the non-treated check. BAS 595XEF combined with Apron XL had the best stripe rust control measured by AUDPC. All treatments did not significantly increase grain test weight compared to the non-treated check. All treatments increased grain yield by 4.9 to 26.8% compared to the non-treated check. However, the increases by Dividend, Raxil MD, and Apron XL were not significant, while those of the other treatments were significant. The results show that BAS 595XEF can be used to reduce early infection of and grain yield losses caused by stripe rust on spring wheat.