Fungicide seed treatments for reducing yield losses caused by stripe rust on winter 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 winter wheat, 2006. Plant Disease Management Reports. 1:ST007.

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 'PS 279' winter wheat was treated with Raxil, Dividend Extreme, and various rates of Alio BAS combined with Apron XL. Seed treated with Apron XL served as a check. The treated seed was planted with an experimental drill planter on 5 Oct 05. Harmony Extra 4.16 g plus Buctril with Agridex was applied on 18 May 06 at stem elongation stage. Stripe rust severity (percent of diseased foliage) was assessed for each plot on 15 Jun at heading stage; 22 Jun at flowering stage; and 28 Jun at soft dough stage. Plots were harvested on 9 Aug when kernels were naturally dry, and test weight of kernels was measured for each plot. Stripe rust severity in Apron-treated check plots was 30.0, 82.5, and 100% on 15 Jun, 22 Jun, and 28 Jun, respectively. All treatments, except for the treatment of Raxil MD, Dividend Extreme, and Alios BAS at the rate of 83.3 ml/100 kg, significantly reduced stripe rust severity compared to the Apron-treated check at the first note on 15 Jun at heading stage. At the second note on 22 Jun and at flowering stage, none of the treatments were significantly different from the Apron check. At the third note on 28 Jun at soft dough stage, all treatments had 100% of rust severity. The treatments were not significantly different in grain test weight. All treatments increased grain yield by 3.8 to 21.3% compared to the Apron-treated check. However, treatments of Alio BAS at rate 333.0 ml/100 kg, 250.0 ml/100 kg, 167.0 ml/100 kg, and Raxil MD had yield significantly higher than that of the Apron check, while the increases by the other treatments were not significant.

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 ‘PS 279’ winter wheat was treated with Raxil, Dividend Extreme, and various rates of Alio BAS combined with Apron XL at 2.78 ml/100 kg. Seed treated with Apron XL at 2.78 ml/100 kg served as a check. The treated seed was planted at 11.3 kg/ha in rows 0.3 m apart with an experimental drill planter on 5 Oct 05. Harmony Extra 4.16 g plus Buctril 0.17 L/ha with Agridex at 1% of spray volume was applied on 18 May 06 at stem elongation 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 15 Jun at heading stage; 22 Jun at flowering stage; and 28 Jun at soft dough stage. Plots were individually measured at the time of harvest and plot area ranged from 6.9 to 7.3 m2. Plots were harvested on 9 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 severity data. Relative AUDPC was calculated as percent of the Apron treatment as 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. Stripe rust severity in Apron-treated check plots was 30.0, 82.5, and 100% on 15 Jun, 22 Jun, and 28 Jun, respectively. All treatments, except for the treatment of Raxil MD, Dividend Extreme, and Alios BAS at the rate of 83.3 ml/100 kg, significantly reduced stripe rust severity compared to the Apron-treated check at the first note on 15 Jun at heading stage. At the second note on 22 Jun and at flowering stage, none of the treatments were significantly different from the Apron check. At the third note on 28 Jun at soft dough stage, all treatments had 100% of rust severity. AUDPC values of the treatments were not significantly different from the Apron check and also not significant different from each other except between treatments of Alio BAS at rate 333.0 ml/100 kg and at 83.3 ml/100 kg. The treatments were not significantly different in grain test weight. All treatments increased grain yield by 3.8 to 21.3% compared to the Apron-treated check. However, treatments of Alio BAS at rate 333.0 ml/100 kg, 250.0 ml/100 kg, 167.0 ml/100 kg, and Raxil MD had yield significantly higher than that of the Apron check, while the increases by the other treatments were not significant.