Efficacy and Economics of Integrating In-Field and Harvesting Strategies to Manage Fusarium Head Blight of Wheat

Abstract

A b s tra c t Salgado, J. D., Madden, L. V., and Paul, P. A. 2014. Efficacy and economics of integrating in-field and harvesting strategies to manage Fusarium head blight of wheat. Plant Dis. 98:1407-1421.Fusarium head blight (FHB), a fungal disease of wheat caused by Fusarium graminearum, and its associated toxins, particularly deoxynivalenol (DON), are best managed by integrating multiple strategies. Experiments were established in 2011 and 2013 to evaluate the effects of integrating cultivar resistance, fungicide application, and grain har vesting strategy on FHB index (IND; field severity), DON, grain yield (YLD), and grain test weight (TW; weight per unit volume). Plots of two moderately resistant and two susceptible cultivars were either treated with 19% tebuconazole + 19% prothioconazole or left un treated, and then inoculated with F. graminearum. IND was rated as the mean percentage of diseased spikelets per spike. Separate subsets of the plots of each cultivar-treatment combination were harvested with one of two combine harvester configuration: C 1 (the default, set at a fan speed of 1,375 rpm and a shutter opening of 70 mm) and C4 (modified, with the same fan speeds but a wider shutter opening of 90 mm). YLD and TW data were collected, and grain samples were rated for percent Fusarium-damaged kernels (FDK) and tested for DON. Results from linear mixed-model analyses showed that the cultivartreatment interaction was significant for all FHB-related responses, with the magnitude of the difference in mean arcsine-square-root-trans formed IND and FDK (arcIND and arcFDK) and log-transformed DON (logDON) between treated and untreated being higher for sus ceptible than moderately resistant cultivars. Plots harvested with the C4 combine configuration had significantly higher mean TW than those harvested with Cl. Treated plots had significantly higher YLD and TW than untreated plots, regardless of cultivar and configuration. Relative to the reference management program (untreated, susceptible cultivar, harvested with Cl), the greatest percent reduction in FDK and DON and increase in YLD was observed for programs that included moderate resistance and fungicide treatment. The greatest percent increase in TW relative to the reference was observed when C4 ad justed combine setting was integrated with resistance and fungicide. Overall, the most effective management programs all included fungi cide treatment, two included moderate resistance, and two included C4 combine setting. Relative to the reference management program, these programs resulted in 30 to 51% reduction in total estimated price dis count, $127 to 312 ha-1 increase in gross cash income, and economic benefit of $31 to 272 ha-1, depending on the level of FHB IND (5 to 15%), grain price ($118 to 276 metric ton-1), and fungicide application cost ($40 to 96 ha-1).

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

“…Consequently, grain contaminated with DON above 2 ppm (threshold established by the United States Food and Drug Administration) may be rejected or priced down by grain buyers (25,26). Further price discounts are usually applied to grain lots with Fusarium-damaged kernels (FDK) above and test weight below established thresholds (26,40,41).…”

“…Many of the moderately resistant soft red winter wheat cultivars have low-to-moderate yield potential when compared with some of the susceptible cultivars. Consequently, producers may earn less as a result of lower grain yield if a resistant cultivar is planted in a low-disease year (40). Similarly, because fungicides are not 100% effective against FHB (11,33,49), producers may incur the costs associated with spraying their fields without seeing the benefits in terms of disease and toxin reduction and grain yield and quality increase.…”

“…However, the development of such models requires knowledge, understanding, and quantitative estimates of losses caused by this disease, as well as quantitative estimates of the effects of different management strategies on FHB, DON, grain yield, test weight, and their relationships. Some work has been done to characterize and quantify some of these effects in detail (6,27,33,34,36,38,40,47,49) but less emphasis has been placed on quantifying the FHB-yield and FHB-test weight relationships. There are numerous reports of yield loss due to FHB in the literature but, in most cases, specific quantitative information pertaining to the FHB-yield relationship is not provided (30).…”

Impact of Fusarium graminearum inoculum availability and fungicide application timing on Fusarium head blight in wheat

“…Yoshida et al (2012) demonstrated that DON could be reduced by applying the fungicide thiophanate-methyl at 20 DAA, but this application timing would not be practical in winter wheat due to the relatively short period of time between anthesis and harvest (~30e40 days). Several studies have evaluated the effect of moderately resistant cultivars on DON levels, but no cultivars have yet been developed that are completely resistant to DON accumulation (Bai et al, 2001;Saldago et al, 2014). Therefore, although combinations of moderately resistant cultivars and fungicide applications are still the best way to reduce DON levels, additional strategies should be investigated to find ways to further reduce DON in grain.…”

Mycotoxins in Wheat and Mitigation Measures

“…Management strategies during harvest include wheat harvest at low moisture or A w , reduced mechanical seed damage, and the use of different grain harvest strategies to remove diseased kernels which are often lighter than the healthy ones. The use different harvesting configurations, with varying fan speeds and shutter openings, resulted in lower Fusarium-damaged wheat kernels and DON content in harvested wheat [99,100]. The removal of damaged grain implies a loss in the yield of harvested grain, but results in better storage conditions and improvement in grain safety offsetting the economic losses.…”