Fusarium Head Blight Epidemics Research Articles

Characterizing the dynamic linkages between environmental changes and wheat Fusarium head blight epidemics

Fusarium head blight (FHB) is a prevalent wheat disease, mainly influenced by environmental factors, such as irradiance, temperature, precipitation, and CO2 levels. Elucidating the relationship between FHB outbreaks and environmental changes is crucial for predictive models and control measures. This study employs historical data to map the dynamic associations between environmental changes and FHB epidemics within a phase space. Complex networks are constructed to analyze the dynamic relationships, followed by an examination and clustering of their topological features and a discussion of similarities and differences. The results revealed structural similarities between the impact of precipitation and CO2 on FHB, as well as between temperature and irradiance on FHB. In addition, precipitation consistently exerts a persistent and sensitive influence on FHB epidemics, while temperature exhibits an inverse relationship. Elevated carbon emissions enhance the effect of CO2 on FHB, while the effect of irradiance on FHB epidemics varies with the solar cycle. This study provides a novel approach to detect and understand the dynamic relationships between FHB epidemics and environmental changes, contributing to enhanced disease surveillance and assessment within complex agriculture systems.

Approaching 25 years of progress towards Fusarium head blight resistance in southern soft red winter wheat (Triticum aestivum L.)

AbstractTremendous progress has been made in variety development and host plant resistance to mitigate the impact of Fusarium head blight (FHB) since the disease manifested in the southeastern United States in the early 2000s. Much of this improvement was made possible through the establishment of and recurring support from the US Wheat & Barley Scab Initiative (USWBSI). Since its inception in 1997, the USWBSI has enabled land‐grant institutions to make advances in reducing the annual threat of devastating FHB epidemics. A coordinated field phenotyping effort for annual germplasm screening has become a staple tool for selection in public and private soft red winter wheat (SRWW) breeding programmes. Dedicated efforts of many SRWW breeders to identify and utilize resistance genes from both native and exotic sources provided a strong foundation for improvement. In recent years, implementation of genomics‐enabled breeding has further accelerated genetic gains in FHB resistance. This article reflects on the improvement of FHB resistance in southern SRWW and contextualizes the monumental progress made by collaborative, persistent, and good old‐fashioned cultivar development.

Into the Trees: Random Forests for Predicting Fusarium Head Blight Epidemics of Wheat in the United States.

Constructing models that accurately predict Fusarium head blight (FHB) epidemics and are also amenable to large-scale deployment is a challenging task. In the United States, the emphasis has been on simple logistic regression (LR) models, which are easy to implement but may suffer from lower accuracies when compared with more complicated, harder-to-deploy (over large geographies) model frameworks such as functional or boosted regressions. This article examined the plausibility of random forests (RFs) for the binary prediction of FHB epidemics as a possible mediation between model simplicity and complexity without sacrificing accuracy. A minimalist set of predictors was also desirable rather than having the RF model use all 90 candidate variables as predictors. The input predictor set was filtered with the aid of three RF variable selection algorithms (Boruta, varSelRF, and VSURF), using resampling techniques to quantify the variability and stability of selected variable sets. Post-selection filtering produced 58 competitive RF models with no more than 14 predictors each. One variable representing temperature stability in the 20 days before anthesis was the most frequently selected predictor. This was a departure from the prominence of relative humidity-based variables previously reported in LR models for FHB. The RF models had overall superior predictive performance over the LR models and may be suitable candidates for use by the Fusarium Head Blight Prediction Center.

Fusarium Head Blight on Wheat: Biology, Modern Detection and Diagnosis and Integrated Disease Management.

Fusarium head blight (FHB) is a major threat for wheat production worldwide. Most reviews focus on Fusarium graminearum as a main causal agent of FHB. However, different Fusarium species are involved in this disease complex. These species differ in their geographic adaptation and mycotoxin profile. The incidence of FHB epidemics is highly correlated with weather conditions, especially rainy days with warm temperatures at anthesis and an abundance of primary inoculum. Yield losses due to the disease can reach up to 80% of the crop. This review summarizes the Fusarium species involved in the FHB disease complex with the corresponding mycotoxin profiles, disease cycle, diagnostic methods, the history of FHB epidemics, and the management strategy of the disease. In addition, it discusses the role of remote sensing technology in the integrated management of the disease. This technology can accelerate the phenotyping process in the breeding programs aiming at FHB-resistant varieties. Moreover, it can support the decision-making strategies to apply fungicides via monitoring and early detection of the diseases under field conditions. It can also be used for selective harvest to avoid mycotoxin-contaminated plots in the field.

Environment, Grain Development, and Harvesting Strategy Effects on Zearalenone Contamination of Grain from Fusarium Head Blight-Affected Wheat Spikes.

Fusarium head blight (FHB), caused by the fungus Fusarium graminearum, is associated with grain contamination with mycotoxins such as deoxynivalenol (DON) and zearalenone (ZEA). Unlike DON, less is known about factors affecting ZEA production during FHB epidemics. The objective of this study was to quantify ZEA contamination of wheat grain as influenced by temperature, relative humidity, FHB index (IND), grain maturation, simulated late-season rainfall, and harvest timing. Mean ZEA concentrations were low (<1.1 ppm) during the early stages of grain development (25 to 31 days after anthesis [DAA]) but rapidly increased 35 to 51 DAA in field experiments, particularly under rainy conditions. Five or ten consecutive days with simulated rainfall shortly before harvest greatly increased ZEA contamination. Similarly, extremely high levels of ZEA (51.8 to 468.6 ppm) were observed in grain from spikes exposed to 100% relative humidity (RH) at all tested temperatures and mean IND levels under controlled conditions. Interestingly, at RH ≤ 90%, ZEA concentrations were very low (0.1 to 3.6 ppm) at all tested temperatures, even at IND above 90%. At 100% RH, mean ZEA contamination was significantly higher at 20 and 25°C (235.1 and 278.2 ppm) than at 30°C (104.7 ppm). Grain harvested early and not exposed to rainfall had lower mean ZEA than grain harvested late and/or subjected to preharvest rainfall. This study was the first to associate ZEA contamination of grain from FHB-affected wheat spikes with temperature and moisture and show through designed experiments that early harvest could be a useful strategy for reducing ZEA contamination.

Adapting to the projected epidemics of Fusarium head blight of wheat in Korea under climate change scenarios.

Fusarium head blight (FHB) of wheat, mainly caused by Fusarium graminearum Schwabe, is an emerging threat to wheat production in Korea under a changing climate. The disease occurrence and accumulation of associated trichothecene mycotoxins in wheat kernels strongly coincide with warm and wet environments during flowering. Recently, the International Panel for Climate Change released the 6th Coupled Model Intercomparison Project (CMIP6) climate change scenarios with shared socioeconomic pathways (SSPs). In this study, we adopted GIBSIM, an existing mechanistic model developed in Brazil to estimate the risk infection index of wheat FHB, to simulate the potential FHB epidemics in Korea using the SSP245 and SSP585 scenarios of CMIP6. The GIBSIM model simulates FHB infection risk from airborne inoculum density and infection frequency using temperature, precipitation, and relative humidity during the flowering period. First, wheat heading dates, during which GIBSIM runs, were predicted over suitable areas of winter wheat cultivation using a crop development rate model for wheat phenology and downscaled SSP scenarios. Second, an integrated model combining all results of wheat suitability, heading dates, and FHB infection risks from the SSP scenarios showed a gradual increase in FHB epidemics towards 2100, with different temporal and spatial patterns of varying magnitudes depending on the scenarios. These results indicate that proactive management strategies need to be seriously considered in the near future to minimize the potential impacts of the FHB epidemic under climate change in Korea. Therefore, available wheat cultivars with early or late heading dates were used in the model simulations as a realistic adaptation measure. As a result, wheat cultivars with early heading dates showed significant decreases in FHB epidemics in future periods, emphasizing the importance of effective adaptation measures against the projected increase in FHB epidemics in Korea under climate change.

Fusarium Head Blight Epidemics in Soft Red Winter Wheat Fields in Georgia from 2018 to 2019

Fusarium head blight (FHB) epidemics on wheat have caused significant yield and economic penalties in the United States since the early 1990s. This report documents FHB epidemics on soft red winter wheat in Georgia in 2018 and 2019. Forty-four wheat fields across 23 counties were assessed for FHB incidence (2019 only), Fusarium-damaged kernel, deoxynivalenol (DON) contamination, and thousand-kernel weight. Higher levels of FHB were observed in 2019 compared with 2018. A significant correlation was observed between DON and 7-day preanthesis weather variables in 2019. FHB parameters were significantly correlated with postanthesis weather variables at 10 days in both years and at 20 and 30 days in 2018, suggesting that postanthesis rather than preanthesis weather had a greater impact on FHB in our study. The combination of hours of conducive temperature and relative humidity postanthesis was consistently correlated with all FHB parameters in both years and could be the best predictor of FHB epidemics. FHB has emerged as the leading threat for soft red winter wheat production in Georgia. Planting moderately resistant wheat cultivars along with in-season management, including proper fungicide application, by closely monitoring the national FHB forecasting system would be the best integrated management strategies for Georgian wheat growers.

Weather Patterns Associated with DON Levels in Norwegian Spring Oat Grain: A Functional Data Approach.

Fusarium graminearum is regarded as the main deoxynivalenol (DON) producer in Norwegian oats, and high levels of DON are occasionally recorded in oat grains. Weather conditions in the period around flowering are reported to have a high impact on the development of Fusarium head blight (FHB) and DON in cereal grains. Thus, it would be advantageous if the risk of DON contamination of oat grains could be predicted based on weather data. We conducted a functional data analysis of weather-based time series data linked to DON content in order to identify weather patterns associated with increased DON levels. Since flowering date was not recorded in our dataset, a mathematical model was developed to predict phenological growth stages in Norwegian spring oats. Through functional data analysis, weather patterns associated with DON content in the harvested grain were revealed mainly from about three weeks pre-flowering onwards. Oat fields with elevated DON levels generally had warmer weather around sowing, and lower temperatures and higher relative humidity or rain prior to flowering onwards, compared to fields with low DON levels. Our results are in line with results from similar studies presented for FHB epidemics in wheat. Functional data analysis was found to be a useful tool to reveal weather patterns of importance for DON development in oats.

Evolution of Fusarium Head Blight Management in Wheat: Scientific Perspectives on Biological Control Agents and Crop Genotypes Protocooperation

Over the past century, the economically devastating Fusarium Head Blight (FHB) disease has persistently ravished small grain cereal crops worldwide. Annually, losses globally are in the billions of United States dollars (USD), with common bread wheat and durum wheat accounting for a major portion of these losses. Since the unforgettable FHB epidemics of the 1990s and early 2000s in North America, different management strategies have been employed to treat this disease. However, even with some of the best practices including chemical fungicides and innovative breeding technological advances that have given rise to a spectrum of moderately resistant cultivars, FHB still remains an obstinate problem in cereal farms globally. This is in part due to several constraints such as the Fusarium complex of species and the struggle to develop and employ methods that can effectively combat more than one pathogenic line or species simultaneously. This review highlights the last 100 years of major FHB epidemics in the US and Canada, as well as the evolution of different management strategies, and recent progress in resistance and cultivar development. It also takes a look at protocooperation between specific biocontrol agents and cereal genotypes as a promising tool for combatting FHB.

Accuracy in the prediction of disease epidemics when ensembling simple but highly correlated models.

Ensembling combines the predictions made by individual component base models with the goal of achieving a predictive accuracy that is better than that of any one of the constituent member models. Diversity among the base models in terms of predictions is a crucial criterion in ensembling. However, there are practical instances when the available base models produce highly correlated predictions, because they may have been developed within the same research group or may have been built from the same underlying algorithm. We investigated, via a case study on Fusarium head blight (FHB) on wheat in the U.S., whether ensembles of simple yet highly correlated models for predicting the risk of FHB epidemics, all generated from logistic regression, provided any benefit to predictive performance, despite relatively low levels of base model diversity. Three ensembling methods were explored: soft voting, weighted averaging of smaller subsets of the base models, and penalized regression as a stacking algorithm. Soft voting and weighted model averages were generally better at classification than the base models, though not universally so. The performances of stacked regressions were superior to those of the other two ensembling methods we analyzed in this study. Ensembling simple yet correlated models is computationally feasible and is therefore worth pursuing for models of epidemic risk.

The Change in Winter Wheat Response to Deoxynivalenol and Fusarium Head Blight Through Technological and Agronomic Progress

Fusarium head blight (FHB) in wheat causes yield loss, quality reduction, and mycotoxin contamination in temperate wheat production areas worldwide. The objective of this study was to quantify the progress of agronomic and FHB management strategies over the past two decades in FHB suppression and agronomic performance of winter wheat in environments favorable for FHB. Field experiments were conducted in environments typical of FHB epidemics to compare common agronomic and FHB management practices used in the 1996 era compared with those used in 2016. The experiments included a comparison of three different nitrogen (N) fertilizer application rates and six old (1996-era) and new (modern-era) winter wheat cultivars representing combinations of susceptibility and era to FHB, with and without a fungicide applied at flowering (pydiflumetofen + propiconazole). To mimic environments favorable for infection (similar to 1996 in Ontario, Canada), plots were challenged at 50% anthesis with F. graminearum macroconidia suspension followed by mist irrigation. The modern management strategy of using moderately resistant cultivars, a fungicide applied at flowering, and a high rate of N fertilizer reduced total deoxynivalenol by 67%, reduced Fusarium-damaged kernels by 49%, reduced FHB index by 86%, increased grain test weight by 11%, and increased grain yield by 31% compared with the standard management practice of seeding highly susceptible cultivars with no fungicide and a lower rate of N fertilizer recommended in the 1996 era. This study enabled a published economic assessment of the return on investment for the improvements in cultivars, fungicide, and N fertilizer applications since 1996.

Multifaceted Insights on Fusarium Head Blight in Small Grains in Pennsylvania

Fusarium head blight (FHB) is a serious disease of small-grain cereals that causes economic losses due to both yield reduction and mycotoxin contamination worldwide. To optimize the regional management of the disease, knowledge of risk factors associated with FHB outbreaks and mycotoxin accumulation are essential steps. Therefore, a 2-year survey was conducted during the summers of 2018 and 2019, in which naturally FHB-affected spikes from different hosts were collected across the major cereal-producing regions of Pennsylvania (South, Central, and North). FHB severity (%) data were recorded from each field. Furthermore, a collection of 307 Fusarium graminearum isolates was used to investigate specific components of the pathogen biology, such as the composition of the trichothecene genotype, saprophytic and pathogenic fitness, and sensitivity to triazole-based fungicides. Our results confirm that FHB is an important disease in Pennsylvania, and the risk of disease epidemics may be impacted by both the year and the location. Overall, the regional population of F. graminearum causing FHB in Pennsylvania is the 15ADON genotype. Based on in vitro and in vivo experiments, F. graminearum populations obtained from three distinct small-grain management regions could not be differentiated for the majority of fitness traits examined. All isolates were sensitive to tebuconazole and metconazole fungicides in vitro. Overall, this new knowledge can help shed light on the relative importance of FHB epidemics in Pennsylvania and provide directions for monitoring the sustainability of the integrated strategies used to manage FHB and mycotoxin accumulation.

First Report of Fusarium poae Causing Fusarium Head Blight of Wheat in Georgia, USA.

Fusarium head blight (FHB) is one of the most troublesome fungal diseases challenging US wheat (Triticum aestivum L.) production (Savary et al. 2019). Harmful mycotoxin contamination, primarily due to deoxynivalenol (DON) in the Fusarium-damaged kernels (FDK), can negatively impact human and livestock health (McMullen et al. 1997). Although Fusarium graminearum is the primary causal agent of FHB, several other species including F. poae could pose a risk by producing dangerous mycotoxins such as nivalenol, DON, HT-2, and T-2 (Stenglein 2009). Severe FHB epidemics on wheat have occurred in recent years along with increased corn acreage across the southeast US specifically in Georgia (Ghimire et al. 2020). Five symptomatic wheat heads displaying bleaching symptoms were randomly collected from 19 different fields across 13 counties of Georgia in late spring of 2018. Infected kernels were dipped in 6% sodium hypochlorite for 10 min and rinsed three times with sterilized water. Blot dried kernels were placed on potato dextrose agar (PDA) and incubated for 7 days at 25°C under 12-h photoperiod. Three isolates (GA18W-2.1.6, GA18W-6.1.4, and GA18W-10.2.3) from Terrell, Peach, and Sumter counties exhibited dense, whitish mycelium colony typical of F. poae (Leslie and Summerell 2006). When grown in carboxymethylcellulose broth, isolates produced globose to piriform microconidia (5.1 to 12.4 µm by 4.4 to 11.2 µm) that were aseptate or had a single septation. The morphological identification was further confirmed by DNA sequencing. Single hyphal tip isolates were grown on cellophane overlain on PDA for 10 days. Fungal DNA was extracted using a Qiagen DNeasy Plant Mini Kit. Genomic DNA was sequenced using TEF1 and TEF2 primer pairs that target the translation elongation factor 1-α (EF1-α) locus (O'Donnell et al. 1998). BLASTn query of the obtained sequences of GA18W-2.1.6 (accession no. MT856907) and GA18W-10.2.3 (accession no. MT856909) were identified as F. poae with a 99% sequence homology with GenBank reference accession MK629641, while GA18W-6.1.4 (accession no. MT856908) displayed 100% similarity with F. poae accession KJ947343. Koch's postulates were performed under greenhouse conditions. Three seeds of the FHB susceptible wheat cultivar 'SS8641' were planted in individual cone-tainers with three replications (two cone-tainers/replicate). Wheat plants were vernalized for six weeks and then moved back to the greenhouse. Each F. poae isolate was spray inoculated (50,000 spores/ml) at the flowering stage onto 18-24 wheat heads. A field isolate of F. graminearum was included as a positive control whereas heads mock-inoculated with water were used as a negative control. Inoculated wheat heads were incubated in black plastic bags for 48 hours. Disease severity and FDK were recorded three weeks post inoculation. Disease severities were 6.7% (GA18W-2.1.6), 8.3% (GA18W-10.2.3), and 15.2% (GA18W-6.1.4) compared to 90.0% in the positive control similar to Arrúa et al (2019). No symptoms were observed in the negative control. FDK was 18% (GA18W-2.1.6), 28% (GA18W-10.2.3) and 44% (GA18W-6.1.4). F. poae was re-isolated from the infected heads and found to be morphologically identical to the isolates used for inoculation. To our knowledge, this is the first report of F. poae associated with FHB of wheat in the state of Georgia, USA. F. poae isolates from Georgia might produce mycotoxins in addition to reducing grain yield which needs further study.

Control of Fusarium graminearum in Wheat With Mustard-Based Botanicals: From in vitro to in planta.

Fusarium graminearum is a phytopathogenic fungus that causes Fusarium head blight in small-grain cereals, such as wheat, with significant yield reductions. Moreover, it contaminates the cereal grains with health-threatening mycotoxins, such as deoxynivalenol (DON), jeopardizing food and feed safety. Plant-based biopesticides, i.e. botanicals, have recently gained increased interest in crop protection as alternatives to synthetic chemical products. The main objective of this study was to test the control efficacy of botanicals based on white or Indian/Oriental mustard seed flours (Tillecur – Ti, Pure Yellow Mustard – PYM, Pure Oriental Mustard – POM, Oriental Mustard Bran – OMB) on F. graminearum infection and mycotoxin accumulation in wheat grain. Botanicals at 2% concentration showed a higher efficacy in inhibiting mycelium growth in vitro compared with a prothioconazole fungicide (F). In the growth chamber experiment under controlled conditions, the spraying agents reduced DON content in grain in the following order: F = Ti = PYM > POM > OMB. The antifungal activity of the botanicals may be attributed to their bioactive matrices containing isothiocyanates (ITCs) and phenolic acids. Allyl ITC was detected in POM and OMB at 8.38 and 4.48 mg g–1, while p-hydroxybenzyl ITC was found in Ti and PYM at 2.56 and 2.44 mg g–1, respectively. Considerable amounts of various phenolic acids were detected in all botanicals. Under field conditions, only the use of F significantly decreased F. graminearum infection and DON content in grain. An additional important finding of this study is that disease control was more difficult when infection was done with ascospores than conidia, which might have several potential implications considering that ascospores are more important in Fusarium head blight epidemics. Our results suggest that mustard-based botanicals are promising biopesticides for the control of Fusarium head blight in small-grain cereals, but for field applications, an appropriate formulation is necessary to stabilize and prolong the antifungal activity, especially against ascospores.

Fusarium graminearum populations from maize and wheat in Ontario, Canada

Ontario has suffered widespread epidemics ofFusarium Head Blight orGibberella Ear Rot roughly every five years since the late 1970s. We undertook a study of the chemotype and genotype ofFusarium graminearum isolated from 1,800 samples of wheat and maize collected across the cereal growing areas over three years. 468 isolates obtained were genotyped and 60 were selected for chemotyping. The dominant genotype has remained the native 15-acetyldeoxynivalenol (15-ADON) population. Approximately 20% of the strains tested were of the native chemotype producing only 15-ADON and one strain producing solely 7α-hydroxy,15-deacetylcalonectrin (3ANX) was observed. The majority of the 15-ADON strains were also capable of producing 3ANX. There was consistent mismatch between chemotype and genotype. This reflects the considerable plasticity in the genes associated with trichothecene biosynthesis documented in severalFusarium species. Although there is a large gradient in climate from southern to eastern Ontario, we did not detect differences in the distribution of the chemotypes. Grain from which strains were isolated for chemotyping were analysed. Approximately half of the 53 samples had &gt;2 mg/kg deoxynivalenol with a maximum of 400 mg/kg and median of 14 mg/kg. 7α-hydroxy,3,15-dideacetylcalonectrin (NX toxin) was detected in three of these samples at an average of 4.5 mg/kg. The stability of theF. graminearum genotype in Ontario can be explained by several factors. Since 1980, the area planted to maize has remained stable, however, the area given to wheat has about doubled. Minimum tillage was rare in 1980 but it is now the norm. Increased crop residue on the soil has greatly increased the biomass of ascocarps that overwinter. Overall, these data demonstrate the need to monitor the mycotoxins inFusarium populations and for the need to consider the potential toxicity of NX in the feed supply.

Identification of QTLs for Resistance to Fusarium Head Blight Using a Doubled Haploid Population Derived from Southeastern United States Soft Red Winter Wheat Varieties AGS 2060 and AGS 2035.

Fusarium head blight (FHB), caused primarily by the fungus Fusarium graminearum, is one of the most damaging diseases of wheat, causing significant loss of yield and quality worldwide. Warm and wet conditions during flowering, a lack of resistant wheat varieties, and high inoculum pressure from corn stubble contribute to frequent FHB epidemics in the southern United States. The soft red winter wheat variety AGS 2060 is moderately susceptible (as opposed to susceptible) to FHB and regularly found in pedigrees of resistant breeding lines. AGS 2060 does not carry any known resistance genes or quantitative trait loci (QTL). A QTL mapping study was conducted to determine the location and genetic effect of its resistance using a doubled haploid mapping population produced from a cross between wheat varieties AGS 2060 and AGS 2035 (FHB susceptible). The population was genotyped using the Illumina iSelect single nucleotide polymorphism (SNP) array for wheat and phenotyped in Baton Rouge and Winnsboro, Louisiana and Newport, Arkansas in 2018 and 2019. The effect of genotype was significant for Fusarium damaged kernels (FDK) and deoxynivalenol (DON) content across all locations and years, indicating genetic variation in the population. The study detected 13 QTLs (one each on chromosome 1A, 1B, 1D, 2A, 2B, 6A, 6B, 7A, and 7B, and two each on 5A and 5B) responsible for the reduction of FDK and/or DON. Of these, nine QTLs for FHB resistance were identified in Winnsboro, Louisiana, in 2019. QTLs on chromosomes 2A and 7A could be valuable sources of resistance to both DON and FDK over several environments and were likely the best candidates for use in marker-assisted selection. Consistently expressed QTLs on chromosomes 5A, 6B, and 7A were potentially newly identified sources of resistance to FHB in soft red winter wheat.

Novel Soil Bacterium Strain Desulfitobacterium sp. PGC-3-9 Detoxifies Trichothecene Mycotoxins in Wheat via De-Epoxidation under Aerobic and Anaerobic Conditions.

Trichothecenes are the most common mycotoxins contaminating small grain cereals worldwide. The C12,13 epoxide group in the trichothecenes was identified as a toxic group posing harm to humans, farm animals, and plants. Aerobic biological de-epoxidation is considered the ideal method of controlling these types of mycotoxins. In this study, we isolated a novel trichothecene mycotoxin-de-epoxidating bacterium, Desulfitobacterium sp. PGC-3-9, from a consortium obtained from the soil of a wheat field known for the occurrence of frequent Fusarium head blight epidemics under aerobic conditions. Along with MMYPF media, a combination of two antibiotics (sulfadiazine and trimethoprim) substantially increased the relative abundance of Desulfitobacterium species from 1.55% (aerobic) to 29.11% (aerobic) and 28.63% (anaerobic). A single colony purified strain, PGC-3-9, was isolated and a 16S rRNA sequencing analysis determined that it was Desulfitobacterium. The PGC-3-9 strain completely de-epoxidated HT-2, deoxynivalenol (DON), nivalenol and 15-acetyl deoxynivalenol, and efficiently eliminated DON in wheat grains under aerobic and anaerobic conditions. The strain PGC-3-9 exhibited high DON de-epoxidation activity at a wide range of pH (6–10) and temperature (15–50 °C) values under both conditions. This strain may be used for the development of detoxification agents in the agriculture and feed industries and the isolation of de-epoxidation enzymes.

Efficacy Assessment of a New Fungicide, Miravis Ace, for Control of Fusarium Head Blight in Wheat

Fusarium head blight (FHB) is a serious disease of wheat and barley that leads to significant economic losses and deteriorated grain quality because of the associated mycotoxins. Genetic resistance and use of fungicides are the methods used to control FHB. However, in weather conditions conducive for FHB epidemics, higher levels of genetic resistance as well as greater efficacy of fungicides are required to adequately control this disease. Due to the extensive use of a single mode of action for management of FHB, there is a need to diversify fungicides used to lower the risk of resistance development in pathogen populations. In this 2-year study, we evaluated the performance of a new fungicide, Miravis Ace (a proprietary mix of pydiflumetofen and propiconazole active ingredients produced by Syngenta) for controlling FHB. It is a mix of succinate dehydrogenase inhibitor and demethylation inhibitor fungicides and can add diversity to the fungicide toolkit for FHB management. The level of control of FHB and deoxynivalenol (DON) achieved by spraying Miravis Ace at anthesis (Feekes growth stage 10.5.1) was found to be equivalent to that provided by the currently recommended products for managing FHB and reducing DON in wheat and barley.

Meta-analysis of QTL for Fusarium head blight resistance in Chinese wheat landraces

Epidemics of Fusarium head blight (FHB), incited by Fusarium graminearum Schwabe, in wheat cause significant reductions in grain yield and quality. Numerous quantitative trait loci (QTL) for FHB resistance have been reported from Chinese sources. However, the relationships among QTL from different landraces have not been characterized. We earlier mapped QTL for FHB resistance using low-density maps developed from five recombinant inbred line (RIL) populations involving Chinese landraces ‘Haiyanzhong’ (HYZ), ‘Wangshuibai’ (WSB), ‘Baishanyuehuang’ (BSYH), ‘Huangfangzhu’ (HFZ), and ‘Huangcandou’ (HCD) as FHB resistant parents. In this study, we used maps of single nucleotide polymorphisms (SNP) developed from the five populations and identified 31 QTL on 16 chromosomes; 10 QTL were new. We constructed a consensus map and identified six meta-QTL (MQTL) and SNP within the MQTL regions using meta-analysis. Two of the MQTL were on chromosome 3BS (3BSd and 3BSc), and one on each of chromosomes 3A, 2D, 3D, and 4D. Twenty-two SNP closely linked to MQTL were converted into breeder friendly Kompetitive Allele Specific Polymerase Chain Reaction (KASP) assays, which should be useful for marker-assisted selection in breeding programs.

Predicting plant disease epidemics from functionally represented weather series

Epidemics are often triggered by specific weather patterns favouring the pathogen on susceptible hosts. For plant diseases, models predicting epidemics have therefore often emphasized the identification of early season weather patterns that are correlated with a disease outcome at some later point. Toward that end, window-pane analysis is an exhaustive search algorithm traditionally used in plant pathology for mining correlations in a weather series with respect to a disease endpoint. Here we show, with reference to Fusarium head blight (FHB) of wheat, that a functional approach is a more principled analytical method for understanding the relationship between disease epidemics and environmental conditions over an extended time series. We used scalar-on-function regression to model a binary outcome (FHB epidemic or non-epidemic) relative to weather time series spanning 140 days relative to flowering (when FHB infection primarily occurs). The functional models overall fit the data better than previously described standard logistic regression (lr) models. Periods much earlier than heretofore realized were associated with FHB epidemics. The findings were used to create novel weather summary variables which, when incorporated into lr models, yielded a new set of models that performed as well as existing lr models for real-time predictions of disease risk. This article is part of the theme issue 'Modelling infectious disease outbreaks in humans, animals and plants: approaches and important themes'. This issue is linked with the subsequent theme issue 'Modelling infectious disease outbreaks in humans, animals and plants: epidemic forecasting and control'.