Sujan Gautam 1, Stephen Wegulo 1, Katherine Frels 2, Heather Hallen-Adams 3, and Kent Eskridge 4
1. Department of Plant Pathology,
2. Department of Agronomy and Horticulture,
3. Department of Food Science and Technology,
4. Department of Statistics, University of Nebraska–Lincoln, Lincoln, Nebraska
Corresponding Author: Stephen Wegulo, swegulo2@unl.edu
Gautam, Sujan
Fusarium head blight (FHB), primarily caused by Fusarium graminearum, continues to be a challenge for wheat production in the US Great Plains. We evaluated the effects of combining cultivar resistance with fungicide application on FHB intensity and yield in winter wheat under field conditions at the University of Nebraska-Lincoln Havelock Research Farm (40°51'17.7"N 96°36'32.2"W). A split-plot randomized complete block design was implemented with four replications. The cultivars served as whole plots: Overland and Zenda, which are moderately resistant, and Wesley and Siege, which are susceptible. There were six subplot fungicide treatments: untreated inoculated check, Prosaro®, Miravis Ace®, Prosaro Pro®, Sphaerex®, and untreated non-inoculated check. Fungicides were applied with a CO2-powered backpack sprayer during anthesis and plots were spray-inoculated with F. graminearum at a concentration of 1 × 10⁵ conidia mL⁻¹ 24 hr after fungicide application. Corn kernel inoculum was applied weekly, starting three weeks before anthesis. FHB index was assessed 21 days after fungicide application. Fusarium-damaged kernels (FDK) and deoxynivalenol (DON) were measured. Mixed-model ANOVA revealed a significant main effect of fungicide treatment on FHB index (F₅, ₆₀ = 5.29, p = 0.0004) and on FDK (F₅, ₆₀= 3.34, p = 0.010). There was a marginal cultivar × treatment interaction for FHB index (p = 0.091). Tukey separation, pooled across cultivars, indicated that the untreated inoculated check had the highest FHB index. All fungicide treatments resulted in significantly (P = 0.05) lower FHB index compared to the untreated non-inoculated check. Prosaro Pro® had the lowest FDK. DON concentrations were consistently low or negligible across all treatments and cultivars at < 0.20 ppm, and there were no effects of cultivar, fungicide treatment or their interaction. Linear regression showed no significant relationship between the FHB index and DON (R² = 0.003, p = 0.622). The low to negligible DON levels were due to low FHB intensity caused by unfavorable environmental conditions for FHB development. Yield and test weight showed no significant differences among fungicide treatments (p> 0.05). 1000-kernel weight varied by cultivar (F₃,₁₂ = 22.16, p < 0.001) but not by fungicide treatment (p = 0.27). Overall, the results support use of fungicide application at anthesis combined with cultivar resistance as an effective management strategy for FHB.
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