The contribution of ground-level inoculum of Fusarium culmorum to ear blight of winter wheat

In a series of field experiments in eastern England over 5 years, severe ear blight developed only in plots of winter wheat that were inoculated by spraying with conidial suspensions of Fusarium culmorum during anthesis, and in which infection was encouraged by rainfall or mist irrigation. In the absence of artificial inoculation of the ears, F. culmorum caused less extensive ear blight, and only where soil-surface inoculum was available after its application on infested plant material (colonized oat grains) up to 3–4 weeks before anthesis; it then developed most where significant rainfall occurred close to the time of anthesis. A warm, dry period following application of inoculum to the ground in late March contributed to increased infection of grain by F. culmorum , although ear blight was not increased. Ear infection therefore depended on adequate viable inoculum on infested plant debris within the crop, and conditions tending to favour brown foot rot development as well as, subsequently, rainfall and moist conditions during anthesis. These conditions did not occur together naturally during this period. Seedling infection by F. culmorum or Microdochium nivale made no significant contribution to ear blight. Inoculation of ears at anthesis with M. nivale or a locally obtained isolate of F. langsethiae did not produce ear blight symptoms. Possibilities for minimizing the availability of inoculum of F. culmorum and the implications for various options for ear-blight control are discussed.     

Relationship between the incidences of ear and spikelet infection of Fusarium ear blight in wheat

There is a urgent need to develop a rational strategy for managing Fusarium ear blight in order to reduce current reliance on routine fungicide applications, based on an objective assessment of disease risks. One of important components for such a management strategy is a fast, easy, accurate and reliable method for disease assessment. The relationship between incidence of Fusarium ear blight ear infection and number of spikelets infected on an ear (or incidence of spikelet infection) were investigated during three seasons and in four countries in order to derive a simple relationship for predicting disease at the spikelet level using ear incidence. More than half of the data sets of the number of infected spikelets on an ear could not be fitted satisfactorily by a Poisson distribution. Three two-parameter discrete distributions (negative binominal, Neyman type A and Polya-Aeppli) provided a significantly better fit than the Poisson distribution, indicating a degree of aggregation of number of infected spikelets on an ear. Taylor's power-law satisfactorily described the observed variance–mean relationship for the number of infected spikelets on an ear; this relationship was generally consistent over years and countries. A robust relationship between incidence of ear infection and average number of infected spikelets per ear was obtained assuming a fixed variance–mean relationship and a negative binomial distribution for the number of infected spikelets. A relationship between incidences of spikelet and ear infection was also obtained based on the complementary log–log or logit transformation of ear and spikelet infection incidence. These models appeared to be consistent over years and countries and thus may be used in making practical disease management decisions involving fungicide applications.     

Relationship between cultivar height and severity of Fusarium ear blight in wheat

A significant negative relationship between tiller height and resistance to Fusarium ear blight (FEB), following inoculation, was observed in 17 cultivars of winter wheat in the 1995/96 growing season. Tall cultivars such as Kraka and Spark showed fewer symptoms of FEB (6 and 4%) than the shorter cultivars Brigadier and Virtue (35 and 51%). To determine if this relationship was caused by a genetic association or an effect of the microclimate, height and disease were measured in segregating populations derived from tall × short cultivars and humidity was measured in near-isogenic lines with and without the Rht1 and Rht2 dwarfing genes. Among random F₃ populations there was a clear tendency for tall strawed lines to show less severe disease symptoms than shorter strawed lines following inoculation. The effect of the individual dwarfing genes Rht1 and Rht2 on the severity of FEB was also studied in an inoculation trial using a number of near-isogenic lines of Maris Huntsman and Maris Widgeon. Within isogenic lines of Maris Huntsman, there was a clear tendency for tall straw to be associated with fewer symptoms, but this was not apparent within lines of Maris Widgeon. Monitoring relative humidity at ear height in a short and tall isogenic line of Maris Huntsman revealed no significant differences between these genotypes from GS 65 to GS 85, suggesting that microclimate cannot explain differences in severity of FEB between these lines. It is suggested that there are independent genes affecting the severity of FEB that may allow plant breeders to select resistant cultivars of any height.     

Fusarium ear blight of wheat: the use of quantitative PCR and visual disease assessment in studies of disease control

Quantitative PCR analysis and visual disease assessment (VDA) were used to study Fusarium culmorum and F. poae ear blight of wheat and its fungicidal control in three glasshouse trials (1994–5 and 1996–7). VDA indicated high levels of both diseases in the trials, while PCR analysis showed that the amounts of F. poae detected in infected plants were low relative to the amounts detected for F. culmorum . PCR and VDA analysis both indicated that the demethylase-inhibiting (DMI) fungicides prochloraz and tebuconazole significantly decreased F. culmorum and F. poae ear blight. The PCR results, however, revealed levels of disease control by fungicide treatments that were consistently higher than those suggested by VDA. Overall, both fungicides appeared equally effective in controlling the two pathogens. PCR and VDA analysis indicated that the anilino-pyrimidine fungicide pyrimethanil had no significant effect on F. culmorum ear blight. Correlations between VDA at cereal growth stage 80 and PCR analysis were similar for F. culmorum and F. poae . Yield analysis, as measured by 1000 grain weight, indicated that DNA content more accurately predicted yield loss than did VDA scores. Inoculation with F. culmorum significantly reduced yield and significant relationships were observed between F. culmorum disease (as assessed visually or by PCR) and yield, with yield decreasing as disease increased. In contrast, inoculation with F. poae had no significant effect on yield and no significant relationships were observed between F. poae disease and yield. These results have important implications for field studies of Fusarium ear blight of wheat because they highlight the importance of identification of the causal organisms to the species level.     

Enhanced overall resistance to Fusarium seedling blight and Fusarium head blight in transgenic wheat by co-expression of anti-fungal peptides

Introduction of alien genes into wheat has been proposed as a strategy to breed cultivars with improved resistance to Fusarium seedling blight (FSB) and Fusarium head blight (FHB). In this study, we co-transformed different anti-fungal peptides (AFPs) into an elite wheat cultivar Yangmai11. We identified the genetically stable transgenic wheat lines carrying single or multiple genes by PCR, qRT-PCR and Southern blot analyses. Transgenic wheat lines 451 and 513 expressing two AFPs displayed a consistent, significantly improved overall resistance to FSB and FHB, whereas only FHB resistance was observed from other lines. Furthermore, crude proteins extracted from the lines 451 and 513 showed a clear inhibitory activity against F. graminearum in vitro. Taken together, it was essential to properly combine and express AFPs in transgenic wheat in order to obtain an improved overall resistance to Fusarium pathogens.     

总结经验提高对小麦赤霉病预防工作重要性的认识

小麦赤霉病是影响安徽省小麦高产、稳产、优质的重要障碍,尤其是在本省沿淮及其以南麦区,对该病的防治更应作为小麦高产、优质栽培的一项重要措施予以高度重视。为阐述小麦赤霉病防治的重要性,笔者近年在凤台县进行了有关调查和试验。     

保湿时间对小麦赤霉病抗性鉴定结果的影响

为优化黄淮麦区小麦赤霉病抗性鉴定方法,于2020年在河南农业大学许昌校区试验田对4个小麦品种进行单花滴注赤霉病抗性鉴定,分析不同套袋保湿天数对病情严重度的影响,并利用与主效抗病基因Fhb1连锁的功能标记TaHRC-STS对其进行分子检测.结果显示:抗病品种'苏麦3号'宁麦9号'携带该基因,而感病品种不携带;套袋1～7...     

Fusarium head blight and mycotoxin contamination of wheat,a review

Summary An infection of bread wheat by fusarium head blight contaminates the crop with mycotoxins, particularly deoxynivalenol (DON) and nivalenol (NIV). The toxicity and natural occurrence of these mycotoxins in wheat are reviewed. Based on 8 years data of fusarium head blight epidemics of wheat in the Netherlands, DON contamination of the grain was estimated. Fusarium head blight ratings averaged an infection of 1.7% of all spikelets; estimates for DON contamination averaged 0.9 mg kg^–1. Taking a guideline level for DON in uncleaned bread wheat of 2 mg kg^–1, in 1979 and 1982 a wheat crop was produced with estimated DON concentrations above the limit of tolerance. Human and animal exposure to mycotoxins in the Netherlands appears to be small but chronic. The information presented in this paper illustrates the need for an annual evaluation of the crop for fusarium head blight incidence and mycotoxin content, and the necessity of fusarium head blight resistant wheat cultivars.Samenvatting Aaraantasting van tarwe doorFusarium culmorum enFusarium graminearum leidt tot vorming van mycotoxinen in het graan, waarvan deoxynivalenol (DON) en nivalenol (NIV) de belangrijkste toxinen zijn. In dit artikel wordt een overzicht gegeven van de toxicologische aspecten, en het voorkomen van deze toxinen in tarwe. Informatie over DON en NIV in tarwe in West-Europa is schaars. Gebaseerd op gegevens vanFusarium epidemieën in de jaren 1979–1986 wordt een schatting gegeven van de concentratie DON in Nederlandse tarwe. Rekening houdend met de herkomst en verwerking van tarwe, blijken zowel in dierlijk als menselijk voedsel lage concentraties DON chronisch voor te komen. Op basis van een maximaal toelaatbare dagelijkse dosis DON van 3 g kg^–1 lichaamsgewicht is de schatting van de dagelijkse opname van DON in het jaar volgend op de oogst van 1982 net op de grens. Zowel een jaarlijkse inventarisatie vanFusarium aantasting en DON besmetting van het graan, als de ontwikkeling vanFusarium-resistente rassen zijn noodzakelijk.     

生物炭对小麦赤霉病的防治效果及产量的影响

为探索生物炭对小麦赤霉病的防治效果和对产量的影响,设置小麦播种前、返青拔节期单施或两个时期均施生物炭处理,在小麦分蘖期人工接种病麦粒,在抽穗扬花期采用孢子捕捉器对穗层空气中的赤霉病菌孢子数量进行动态监测,并在乳熟期调查各处理的病穗率和病情指数,成熟期测定各处理的理论产量、实际产量和籽粒中脱氧镰刀菌烯醇(deoxynivalenol,DON)毒素的含量。结果表明,施用生物炭后穗层赤霉病菌孢子的数量显著降低,赤霉病病情指数降低,且以基施和返青拔节期追施13 500 kg/hm~2生物炭的处理最优;施用生物炭后小麦千粒重和株高均显著增加(P0.05),其中基施和追施13 500 kg/hm~2生物炭的处理较对照处理增产29.5%(P0.05)。     

河南省首次发现梨孢镰刀菌引起的小麦赤霉病

2015年从河南省田间小麦赤霉病病穗上分离得到一种生长速度较慢的镰刀菌, 通过形态学和分子鉴定明确其分类地位, 通过田间单小花滴注法和喷雾法接种测定其致病力, 并通过高效液相色谱串联质谱分析对麦穗中的毒素种类进行测定, 明确其产毒特征?结果表明:分离得到的8个菌株均为梨孢镰刀菌, 在马铃薯葡萄糖琼脂(PDA)培养基上为白色菌落, 菌落底部产生少量红色色素, 平均生长速度为13.3 mm/d; 小型分生孢子为椭球形葡萄状, 平均大小为7.1 μm×5.8 μm, 未见大型分生孢子和厚垣孢子; 致病力弱, 且不侵染穗轴, 单小花滴注法接种条件下平均病级为0.1, 喷雾法接种条件下平均病小穗率为6.5%; 供试的8个镰刀菌菌株均不产生T-2和HT-2毒素, 均产生雪腐镰刀菌烯醇(NIV)毒素, NIV毒素含量水平为371.74~5 282.80 μg/kg, 其中3个菌株产生少量脱氧雪腐镰刀菌烯醇(DON)毒素(86.13~227.22 μg/kg)?     

麦类赤霉病研究进展

由镰刀菌引起的麦类赤霉病是大麦和小麦最重要的病害之一。本文综述了近年来在麦类赤霉病致病病原菌种及分子鉴定、病原菌产毒及毒素化学型分子检测、大、小麦赤霉病病原菌种群结构、病原菌抗药性及新药剂研发、病害流行预测和品种抗病性研究等方面的进展。     

A model estimating the risk of Fusarium head blight on wheat*

A dynamic simulation model for the risk of Fusarium head blight on wheat was elaborated based on systems analysis. The model calculates a daily infection risk based on sporulation, spore dispersal and infection of host tissue of the four main species causing the disease (Gibberella zeae, Fusarium culmorum, Gibberella avenacea, Monographella nivalis). Spore yield and dispersal are calculated as functions of temperature, rainfall and relative humidity, while the main factors affecting the infection rate are temperature, wetness and the host growth stage. The model also calculates a risk for mycotoxin production by G. zeae and F. culmorum in the infected head tissue. First validations against field data, collected in some wheat‐growing areas in northern Italy and not used in model elaboration, produced satisfactory results.     

Fusarium ear blight (scab) in small grain cereals—a review

This review of Fusarium ear blight (scab) of small grain cereals has shown that up to 17 causal organisms have been associated with the disease, which occurs in most cereal-growing areas of the world. The most common species were Fusarium graminearum (Gibberella zeae), F. culmorum, F, avenaceum (G, avenacea), F, poae and Microdochium nivale (Monographella nivalis). The disease was recorded most frequently under hot, wet climatic conditions where significant yield losses and mycotoxin accumulation in grain were reported. Possible sources of inoculum were reported as crop debris, alternative hosts and Fusarium seedling blight and foot rot of cereals. The mode of dispiersal of inoculum to ears remains unclear, but contaminated arthropod vectors, systemic fungal growth through plants, and wind and rain-splash dispersal of spores have been proposed. Infection of wheat ears was shown to occur mainly during anthesis, and it has been demonstrated that fungal growth stimulants may be present in anthers. Despite the importance of the disease, particularly during epidemic years, control methods are limited. Much effort has gone into breeding resistant wheat varieties and into improving our understanding of the possible mechanisms and genetic basis of resistance, with only moderate success. There are also surprisingly few reports of successful fungicidal or biological control of the disease in the field.     

江苏小麦赤霉病综合防控关键技术研究

近年来气候变暖、秸秆还田和赤霉病菌对多菌灵的抗性上升使江苏省小麦赤霉病流行频率提高。本研究通过田间小区试验,对小麦赤霉病的综合防控关键技术进行了比较。试验结果表明,目前赤霉病菌对多菌灵抗药性频率已达60%以上,多菌灵的防效明显下降,低于60%。研究明确了赤霉病的防控适期和防治次数,对淮南、淮北主要小麦品种进行赤霉病自然发病鉴定,并阐述了品种抗性和药剂防治间的互作效应。研究结果揭示,选育推广对小麦赤霉病具有抗性的品种是小麦赤霉病防控的基础,把握适期于小麦扬花期施用非多菌灵类的戊唑醇、氰烯菌酯、丙硫菌唑等其他杀菌剂可有效控制病害的发生。     

不同杀菌剂防治小麦赤霉病及减少籽粒中DON毒素积累的效果

为明确不同杀菌剂防治小麦赤霉病和减少小麦籽粒中DON(脱氧雪腐镰刀菌烯醇)毒素积累的效果,于大田人工接菌条件下进行了不同杀菌剂对小麦赤霉病的防治试验,并于收获期测定了不同药剂处理的小麦籽粒中DON毒素含量。结果表明:两种处理方式下,50%多菌灵WP,30%多·酮SC,25%戊唑醇WP,25%氰烯菌酯SC和70%甲基硫菌灵WP处理中,除先喷药后接菌条件下25%戊唑醇WP在病粒率和籽粒中DON积累上没有显著防治效果,接菌后1d喷药条件下50%多菌灵WP、25%戊唑醇WP在病粒率上没有显著防治效果;30%多·酮SC在病粒率和籽粒中DON积累上没有显著防治效果外,各处理对小麦的病穗率、病情指数、病粒率和籽粒中DON积累都有显著的防治效果(P0.05)。各处理的病穗率防效在42.4%~83.5%,病情指数防效在44.9%~88.2%,病粒率防效在34.7%~69.4%,籽粒中DON防效在48.0%~86.9%。上述几种杀菌剂具有明显的保护作用,其在先喷药后接菌条件下的防治效果均明显优于接菌后1d喷药的防治效果。两种处理方式下,30%己唑醇悬浮剂、25%嘧菌酯悬浮剂和12.5%烯唑醇可湿性粉剂处理在病穗率、病情指数、病粒率和籽粒中DON积累与清水对照处理没有显著性差异(P0.05)。     

Silicon amendment improves wheat defence against Fusarium graminearum and complements the control by fungicide of Fusarium head blight

A three-year field experiment with two wheat cultivars evaluated the effect of soil-applied silicon (Si), with and without fungicide spraying, on Fusarium head blight (FHB) control. Silicon treatment alone reduced FHB severity and the percentage of damaged wheat kernels, regardless of the cultivar. The best disease control was obtained for the cultivar with moderate disease resistance (MR), supplied with silicon and treated with fungicide during flowering. Silicon treatment alone promoted an increase in deoxynivalenol (DON) concentration in the disease-susceptible cultivar; however, in the MR cultivar, silicon amendment associated with fungicide treatment led to a reduction in DON concentration. Greenhouse experiments evaluated the effect of silicon combined with different timings of fungicide application on wheat defences against Fusarium graminearum. Plants supplied with silicon had a longer pathogen incubation period, lower FHB severity and lower DON concentration when compared to plants without silicon. In addition, silicon-supplied plants had higher soluble phenolic content and altered antioxidant enzyme activities (SOD, CAT, POX and PPO) that favoured early accumulation of hydrogen peroxide when compared to plants without silicon. Greater control of FHB and lower DON concentration in plants treated with silicon and fungicide before inoculation and up to 1 day after inoculation was associated with increased levels of defence-associated metabolites. Silicon contributed to the reduction of FHB and DON concentration in wheat, especially for the MR cultivar and, when combined with fungicide spraying, both MR and disease-susceptible cultivars had enhanced performances upon silicon amendment.     

Restriction fragment length polymorphism analysis of variation in Fusarium species causing ear blight of cereals

Genetic variation in Fusarium species on wheat was investigated using restriction fragment length polymorphism (RFLP) analysis. Single-spore lines (76) of Fusarium were recovered from 24 ears of wheat in a field plot exhibiting severe symptoms of Fusarium ear blight and identified using classical taxonomic criteria. Four Fusarium species were present, of which F. avenaceum and F. culmorum were predominant with F. lateritium and F. poae present in two ears and one ear, respectively. RFLP analysis using rDNA (pTA71) or total genomic DNA from an F. culmorum isolate clearly distinguished the four species. Genetic fingerprints of the isolates generated using DNA of bacteriophage M13 (which contains a mini-satellite repeat sequence) revealed considerable variation within three of the four species (except F. poae). Generally, only a single clone was recovered from each ear and in all but one case only a single species was obtained from each spikelet. However, in several instances it appeared that more than one clone of a species was present within a single spikelet.     

不同杀菌剂对小麦赤霉病和叶锈病的防治效果

为明确不同杀菌剂防治小麦赤霉病和叶锈病的效果,在大田条件下进行了不同杀菌剂对这两种病害的防治试验.对小麦赤霉病的防效结果表明:25％氰烯菌酯SC、20％叶菌唑SC、48％氰烯·戊唑醇SC和200 g/L氟唑菌酰羟胺SC的防效较好,防效为83.54％～88.92％;其次为400 g/L戊唑·咪鲜胺EW和430 g/L戊唑...