Evaluation of foliar fungicides for management of wheat diseases in Indiana, 2008.

摘要

Foliar fungicides of wheat were evaluated at the Purdue Agronomy Center for Research and Education (ACRE) in Tippecanoe County and at the Southeast Purdue Agricultural Center (SEPAC) in Jennings County. Before seeding at ACRE, 17gal of 10-34-00 fertilizer plus 3 gal/A of 28-0-0 was incorporated into the soil. The soft red winter wheat cultivar Pioneer 25R78 was drilled at 7.5-in. row spacing on 12 Oct 07 at ACRE and 22 Oct 07 at SEPAC. Plots were 6.4 ft wide and 20 ft long at eachlocation, and the experiment was designed as a randomized complete block with four replications. Plots were top-dressed on 25 Mar with 125 lb/A of nitrogen at ACRE, and Harmony Extra at 0.5 fl oz/A was applied in the early spring to control weeds.Plots at SEPAC were top-dressed on 13 Mar with 324 lb/A of 28-0-0, and Harmony Extra at 0.5 fl oz/A with 1 pt/100 gal of nonionic surfactant was applied on 16 Apr for weed control. Fungicide treatments were applied with a CO2-pressurized backpacksprayer and a hand-held boom fitted with paired TJ 8001VS nozzles directed forward and backward at a 45° angle, to deliver 27 gal/A at 40 psi. Fungicides were applied 24 April at both locations when the first node was visible (Feekes growth stage 6), andagain on 9 May when the flag leaf was visible (FGS 9) at ACRE and 7 May at SEPAC. A third application when boots were swollen (FGS 10) was made on 13 May at ACRE and 9 May at SEPAC. The last application at each location at the beginning of flowering (FGS10.51) was intended to manage Head blight (HB) and was applied on 27 May at ACRE and 16 May at SEPAC.Disease developed from natural inoculum at both locations. Severity of Septoria blotch (SB) was visually assessed using the 0-9.5 Septoria scale. Leaf rust was visually assessed by percent infection (0-100%) of the flag leaf. Plots were harvested with asmall plot research combine on 26 Jun at ACRE and 2 Jul at SEPAC. Grain yield, moisture content, and test weight werecollected, and yields were adjusted to 13.5% grain moisture before analysis. Data were subjected to analysis of variance andmeans were compared at the 0.05 significance level using Fisher’s protected least significant difference (LSD) test. A sub-sampleof grain from each plot at ACRE was sent to the University of Minnesota for analysis of deoxynivalenol (DON) content.