Authors: Juliet M. Marshall 1,2, Sidrat Abdullah 2,Linda Jones 2, and Tod Shelman2
1. University of Idaho, Idaho Falls, ID 83402
2. University of Idaho, College of Agricultural and Life Sciences, Aberdeen Research and Extension Center, Aberdeen, ID 83210
Corresponding Author: Juliet M. Marshall, jmarshall@uidaho.edu
Presenting Author: Sidrat Abdullah
Abstract
The trial at the University of Idaho research farm in Aberdeen, ID used soft white spring wheat 'WB6211CLP' (highly FHB-susceptible) to evaluate fungicide efficacy against Fusarium Head Blight (FHB). In order to optimize disease development, experimental plots were set up in a randomized full block design with four replications, planted on May 1, 2024, under irrigation. An additional supplementary sprinkler system was installed across the experimental plot to create an environment conducive for disease infection and development at anthesis. Different fungicide combinations were used as treatments applied at 50% anthesis and 4-6 days later, following the UFT protocol. Treatments 1 (untreated check) and 4 (Miravis Ace 13.7 oz/A applied with NIS Induce at anthesis) were requested by USWBSI, Bayer and Syngenta. A Fusarium graminearum spore suspension (100,000 spores/ml) was used in the afternoon of July 8, the same day as the anthesis fungicide treatments were applied that morning. The second fungicide application occurred 15 July for treatments 8 and 9. The FHB index was calculated as (incidence × severity) / 100. FHB ratings, including incidence and severity, were recorded 23 days after anthesis. There was no evidence of phytotoxicity after fungicide treatments. Plots were harvested on 6 Sept with a small plot combine. Yield and test weight was determined utilizing the HarvestMaster system on the combine. Analysis used PROC GLIMMIX in SAS 9.4 with LSD (α = 0.05) for mean comparisons. Even while untreated check plots achieved an FHB score of 47%, the results indicated that cooler, wet spring conditions reduced FHB growth. Fungicide treatments effectively decreased FHB incidence, severity, and index as compared to untreated plots, with significant reductions (P<0.01) observed across disease and yield metrics. The untreated check plot had a lower test weight (55 lbs/bu) and the lowest grain yield (77 bu/A). All fungicide treatments had yields that were statistically comparable, but Treatment 8, which included Miravis Ace and Sphaerex, produced the highest yield at 100 bu/A. Mean FHB incidence, severity, and index ranged from 15 to 70%, 17 to 68%, and 3 to 47%, respectively, with untreated plots showing the highest values. Test weight (P<0.0001), yield (P<0.01), FHB incidence (P<0.01), FHB severity (P<0.0001), and FHB index (P=0.0001) all showed significant differences. DON results are pending. All fungicide applications successfully decreased FHB infection. Fungicide treatments improved yield and grain quality while effectively controlling FHB, thus supporting their role in FHB management strategies for spring wheat.