Quantifying the Effects of Fusarium Head Blight on Grain Yield and Test Weight in Soft Red Winter Wheat

Abstract

Fusarium head blight (FHB), caused by the fungus Fusarium graminearum, is known to negatively affect wheat grain yield (YLD) and test weight (TW). However, very little emphasis has been placed on formally quantifying FHB-YLD and FHB-TW relationships. Field plots of three soft red winter wheat cultivars-'Cooper' (susceptible to FHB), 'Hopewell' (susceptible), and 'Truman' (moderately resistant)-were grown during the 2009, 2010, 2011, and 2012 seasons, and spray inoculated with spore suspensions of F. graminearum and Parastagonospora nodorum to generate a range of FHB and Stagonospora leaf blotch (SLB) levels. FHB index (IND) and SLB were quantified as percent diseased spike and flag leaf area, respectively, and YLD (kg ha(-1)) and TW (kg m(-3)) data were collected. Using IND as a continuous covariate and cultivar (CV) and SLB as categorical fixed effects, linear mixed-model regression analyses (LMMR) were used to model the IND-YLD and IND-TW relationship and to determine whether these relationships were influenced by CV and SLB. The final models fitted to the data were of the generic form y=a+b (IND), where a (intercept) or b (slope) could also depend on other factors. LMMR analyses were also used to estimate a and b by combining the studies from these 4 years with an additional 16 experiments conducted from 2003 to 2013, and bivariate random-effects meta-analysis was used to estimate population mean b ([Formula: see text]) and a (ā) for the IND-YLD relationship. YLD and TW decreased as IND increased, with b ranging from -3.2 to -2.3 kg m(-3) %(-1) for TW. For the IND-YLD relationship, [Formula: see text] was -51.7 kg ha(-1) %IND(-1) and ā was 4,426.7 kg ha(-1). Neither cultivar nor SLB affected the IND-YLD relationship but SLB affected a of the IND-TW regression lines, whereas cultivar affected b. Plots with the highest levels of SLB (based on ordinal categories for SLB) had the lowest a and Hopewell had the highest b. The level of IND at which a 50-kg m(-3) reduction in TW was predicted to occur was 19, 16, and 22% for Cooper, Hopewell, and Truman, respectively. A yield loss of 1 MT ha(-1) was predicted to occur at 19% IND. The rate of reduction in relative TW or YLD per unit increase in IND was between -0.39 and -0.32%(-1) for TW and -1.17%(-1) for YLD. Results from this study could be integrated into more general models to evaluate the economics of FHB management strategies.

Modeling of Yield Losses and Risk Analysis of Fungicide Profitability for Managing Fusarium Head Blight in Brazilian Spring Wheat

“…neither wheat cultivar nor the presence of foliar disease Stagonospora leaf blotch (SLB) significantly affected the slopes (Salgado et al 2015).…”

“…The profitability tended to increase in general after the 1990s, when a single fungicide spray, but not often two sprays, was more likely to pay-off. Caution is needed in interpretation because we are not taking into account the effect of fungicide sprays on other traits affected by FHB such as test weight and mycotoxin, which downgrade grain value (Salgado et al 2014(Salgado et al , 2015.…”

“…Thus, these efforts have generated a large amount of epidemiological data (Kazan et al 2012;McMullen et al 2012;Shah et al 2018). These large data sets have enabled the use of meta-analytic approaches to study the effects of fungicides on disease control, yield increase and mycotoxin reduction, as well as to explore empirical relationships between FHB index and wheat yield or mycotoxin levels (Madden and Paul 2009;Salgado et al 2011Salgado et al , 2014Salgado et al , 2015. Meta-analysis has become standard for studying empirical relationships between disease and yield data for other diseases like soybean rust (Dalla Lana et al 2015), soybean white mold (Lehner et al 2017) and soybean target spot (Edwards Molina et al 2018).…”

“…The majority of studies on the relationship between FHB intensity and variables like yield or mycotoxin have been conducted in the temperate regions in North American cropping conditions (Madden and Paul 2009;Salgado et al 2011), which differ from subtropics of South America in both abiotic and biotic factors, as well as management practices Spolti et al 2014). In North America, for example, the relationship between FHB index and yield was quantified using field trials from multiple location-years to estimate damage coefficients (percent reduction in yield per percent point increase in FHB index) for winter wheat (Madden and Paul 2009;Salgado et al 2015) and spring wheat (Madden and Paul 2009).…”

Do single, double or triple fungicide sprays differentially affect the grain quality in winter wheat?

“…4) suggests that other factors such as environmental conditions or interactions between environment and genotype might play a role in this variability (Khalil et al, 2002). As FHB plays a role in TW (Salgado et al, 2015), another possible reason for the lower TW values in Burmerange in 2007 can be attributed to the extremely high level of FHB detected in that year in the country. In addition, Burmerange was the location with the highest average severity of infected spikelets per head found in the country.…”