Head Blight Incidence Research Articles

Wheat grain and straw yield, grain quality, and disease benefits associated with increased management intensity

AbstractWheat (Triticum aestivum L.) is the third‐most cultivated field crop in the United States and a very important source of nutrition globally. The economic value of wheat motivates farmers to optimize yield and grain quality, which can be obtained with additional inputs that are often expensive. This study investigated three management intensity levels on grain yield, straw yield, grain test weight, and disease on winter wheat in Wisconsin across 4 yr and 20 varieties. All management practices included a pre‐emergence herbicide and N application, with a mid‐level management strategy adding another N application and a single fungicide application to the current strategy, and a high‐level management intensity strategy adding a growth regulator, two micronutrient applications, and another fungicide application to the mid‐level strategy. Our study revealed that increasing management intensity from current strategies to mid‐ or high levels significantly increased grain yields by 0.81–1.22 kg ha−1, straw yields by 1.2–1.2 t ha−1, and grain test weights by 2.6–3.2 kg hl−1, respectively (P < .05). In addition, the high‐level management intensity led to significant reductions in stripe rust incidence and severity, whereas both mid‐ and high‐level management intensity reduced Fusarium head blight incidence and severity, and mycotoxin contamination (P < .001). The economic considerations of intensified management were also examined, and the mid‐ and high‐level management practices resulted in US$306 and US$242 ha−1 greater profit than current management, respectively, as a result of the improved disease protection and yields.

Interaction between Fusarium head blight and crown rot disease incidence and cultural practices on wheat in the south of Iraq, Basra province

BackgroundThis study was conducted to estimate Fusarium head blight (FHB) and crown rot (FCR) disease incidence on wheat and their interaction with cultural methods (cultivar types, planting time, seed rate, crop rotation, and fertilizer practices) that are used in wheat cropping system in the south of Iraq, Basra province.ResultsThe results showed that the mean average of FHB and FCR was 27.2% and 31%, respectively. This displays that very nearly one-third of wheat crop planted in those 14 fields were infected by both diseases but not very severely, except in two fields (D and HM), which were devastating, 54% and 71% and 41% and 52% for FHB and FCR, respectively. The highest level of incidence for both diseases was associated with the earlier and latest planting dates 28 Oct. and 10 Dec., while the lowest was with 1, 10, and 23 Nov. A 200 and 120 kg/ha were the highest and lowest seed rates used in this study. The selected wheat fields differed in their pre-crop rotations (legume, corn, sorghum, okra, and continuous cropping system of wheat) in a previous year. The amount of added fertilizers (urea, DAP, and NPK) to the studied fields was in a high variation. The seven wheat cultivars examined in this study showed different levels of susceptibility to both diseases.ConclusionThe results verified that most of the agricultural practices examined in this study were associated with positive correlation for FHB and FCR in the occurrence of disease incidence. Except the cultivar type and fertilizer application had unclear relationship with the incidence of both diseases.

Head and Leaf Fungicide Deposit on Winter Wheat, Deoxynivalenol Content and Yield Parameters As Affected by Different Nozzle Types

In 2014 and 2015, we studied the effect of fungicide spraying with 11 different nozzles on the quality and quantity of head and leaf fungicide deposit, the percentage of Fusarium head blight (FHB) incidence, FHB index, the DON content, yield and grain quality parameters. The best quality and quantity of fungicide deposit on the front and rear head sides was achieved with the TeeJet Turbo FloodJet TF VP2 nozzle (FLOOD) and the Albuz AVI-TWIN 110-03 nozzle (AVI). In comparison with the majority of treatments, the FHB incidence and the FHB index was the highest on the unsprayed control. The FHB index was higher using the Lechler IDK 120-03 nozzle (IDK) than with the other nozzle types. In all the treatments, the DON content in the grain was less than 50 µg/kg. At this very low level of infection this is not surprising. The grain yield was the smallest on the unsprayed control. Better fungicide coverage of wheat heads with the FLOOD and AVI nozzles did not result in a statistically higher yield or better grain quality parameters. Negative correlations were confirmed between yield and variables as DON content, FHB incidence and FHB index and also between falling number and variables as fungicide coverage, FHB incidence and FHB index. Positive correlations were determined between DON content and FHB incidence, between hectolitre weight and variables as spray deposit and coverage and between protein content and variables as spray deposit and coverage.

Fusarium head blight incidence and mycotoxin accumulation in three durum wheat cultivars in relation to sowing date and density

Durum wheat (Triticum turgidum var. durum) is an important crop in Europe, particularly in the Mediterranean countries. Fusarium head blight (FHB) is considered as one of the most damaging diseases, resulting in yield and quality reduction as well as contamination of grain with mycotoxins. Three winter durum wheat cultivars originating from Austria, Slovakia, and Poland were analyzed during 2012–2014 seasons for FHB incidence and Fusarium mycotoxin accumulation in harvested grain. Moreover, the effects of sowing density and delayed sowing date were evaluated in the climatic conditions of Southern Poland. Low disease severity was observed in 2011/2012 in all durum wheat cultivars analyzed, and high FHB occurrence was recorded in 2012/2013 and 2013/2014 seasons. Fusarium graminearum was the most abundant pathogen, followed by Fusarium avenaceum. Through all three seasons, cultivar Komnata was the most susceptible to FHB and to mycotoxin accumulation, while cultivars Auradur and IS Pentadur showed less symptoms. High susceptibility of cv. Komnata was reflected by the number of Fusarium isolates and elevated mycotoxin (deoxynivalenol, zearalenone, and moniliformin) content in the grain of this cultivar across all three seasons. Nivalenol was identified in the samples of cv. Komnata only. Genotype-dependent differences in FHB susceptibility were observed for the plants sown at optimal date but not at delayed sowing date. It can be hypothesized that cultivars bred in Austria and Slovakia show less susceptibility towards FHB than the cultivar from Poland because of the environmental conditions allowing for more efficient selection of breeding materials.

Fusarium head blight incidence and detection of Fusarium toxins in wheat in relation to agronomic factors

We investigated incidences of Fusarium head blight (FHB) and concentrations of six mycotoxins (deoxynivalenol, nivalenol, 3-acetyldeoxynivalenol, T-2 toxin, HT-2 toxin and zearalenone) in wheat from 2010 to 2013. Field trials were conducted at the Experimental Station of Cultivar Testing in Chrząstowo, Poland (53o11’N, 17o35’E). We examined the effects of four agronomic factors, including pre-crop type (corn, sugar beets and wheat), date of sowing (late autumn: November 8–December 9 or spring: March 29–April 19), fungicidal application (untreated or treated with two applications) and cultivar (Monsun, Cytra), on FHB index (FHBi) and mycotoxin levels in order to minimize the risk of wheat grain contamination by mycotoxins via integrated pest management methods. The dominant Fusarium species observed on wheat heads were F. culmorum, F. avenaceum (Gibberella avenacea) and F. graminearum (Gibberella zeae), at 21.1%, 17.2% and 7.1%, respectively. A monthly rainfall sum of 113.9 mm and a relatively low air temperature (monthly average 15.5 °C) resulted in the highest FHBi in untreated wheat (25.1%). Agronomic factors crucial for the FHB incidence were the pre-crop, fungicidal treatments and cultivar selection. In wheat planted after wheat or corn, the FHBi was higher compared with a pre-crop of sugar beet. A double application of fungicides at BBCH 30–32 with prothioconazole and spiroxamine and at a BBCH 65 with fluoxastrobin and prothioconazole effectively reduced the FHBi and mycotoxin concentrations, respectively, in grain. The cultivar ‘Cytra’ had a greater FHBi (10.4%) than ‘Monsun’ (4.6%), and grain infestations by Fusarium species were also greater in ‘Cytra’, at 16.5%, than in ‘Monsun’, at 11.2%. Untreated cv. Cytra grown after corn in spring produced grains with the highest amounts of the mycotoxins, deoxynivalenol, 3-acetyldeoxynivalenol, zearalenone and HT-2 (605, 103, 17.5 and 5.53 μg/kg, respectively). Total mycotoxin levels in wheat were correlated with five determinants: duration of the period between the end of flowering and the beginning of kernel abscission, FHBi, F. culmorum isolation, G. zeae isolation and Fusarium ratio (FR) as a % of total mould isolations. Although, the mean concentration of mycotoxins in grain did not exceed the maximum permissible values for unprocessed wheat our study suggests necessity to monitor and mitigate FHB risk for susceptible cultivars, when wheat spring sowing follows corn or wheat.

Mapping QTLs for Fusarium Head Blight Resistance in an Interspecific Wheat Population.

Fusarium head blight (scab) is one of the most widespread and damaging diseases of wheat, causing grain yield and quality losses and production of harmful mycotoxins. Development of resistant varieties is hampered by lack of effective resistance sources in the tetraploid wheat primary gene pool. Here we dissected the genetic basis of resistance in a new durum wheat (Triticum turgidum ssp. durum) Recombinant inbred lines (RILs) population obtained by crossing an hexaploid resistant line and a durum susceptible cultivar. A total of 135 RILs were used for constituting a genetic linkage map and mapping loci for head blight incidence, severity, and disease-related plant morphological traits (plant height, spike compactness, and awn length). The new genetic map accounted for 4,366 single nucleotide polymorphism markers assembled in 52 linkage groups covering a total length of 4,227.37 cM. Major quantitative trait loci (QTL) for scab incidence and severity were mapped on chromosomes 2AS, 3AL, and 2AS, 2BS, 4BL, respectively. Plant height loci were identified on 3A, 3B, and 4B, while major QTL for ear compactness were found on 4A, 5A, 5B, 6A, and 7A. In this work, resistance to Fusarium was transferred from hexaploid to durum wheat, and correlations between the disease and morphological traits were assessed.

Climate, Soil Management, and Cultivar Affect Fusarium Head Blight Incidence and Deoxynivalenol Accumulation in Durum Wheat of Southern Italy.

Fusarium head blight (FHB) is a multifaceted disease caused by some species of Fusarium spp. A huge production of mycotoxins, mostly trichothecenes, often accompanied this disease. Amongst these toxic compounds, deoxynivalenol (DON) and its derivatives represent a major issue for human as well as for animal health and farming. Common and durum wheat are amongst the hosts of trichothecene-producing Fusaria. Differences in susceptibility to fungal infection and toxin accumulation occur in wheat cultivars. Recently, increasing incidence and severity of Fusarium infection and a higher DON accumulation in durum wheat were observed in Italy, especially in Northern regions. In this study, we analyzed wheat yield, technological parameters, the incidence of Fusarium infection and DON content in kernel samples of durum wheat coming from three locations of Southern Italy with different climatic conditions and grown during two seasons, with two methods of cultivation. Four different durum wheat cultivars prevalently cultivated in Southern Italian areas were chosen for this study. Our analysis showed the effects of environment and cultivar types on wheat productivity and key technological parameters for the quality level of the end-product, namely pasta. Notably, although a low rate of mycotoxin contamination in all study sites was assessed, an inverse relation emerged between fungal infection/DON production and durum wheat yield. Further, our study pinpoints the importance of environment conditions on several quality traits of durum wheat grown under Mediterranean climate. The environmental conditions at local level (microscale) and soil management practices may drive FHB outbreak and mycotoxin contamination even in growing area suitable for cropping this wheat species.

Fusarium head blight (FHB) and Fusarium spp. on grain of spring wheat cultivars grown in Poland

AbstractEighteen spring wheat cultivars, recommended for commercial production in northern Poland, were assessed for Fusarium head blight (FHB) in natural non-epidemic conditions, from 2011 to 2013. Assessment was based on FHB incidence (proportion of heads with symptoms), disease severity (DS; proportion of bleached spikelets per head), proportion ofFusariumdamaged kernels (FDK), and spectrum ofFusariumspp. colonising the kernels. Fusarium head blight incidence and DS often differed significantly among cultivars and years. There was a strong positive correlation between FHB incidence and DS. Fusarium head blight incidence and DS were not correlated with the June–July temperatures, and were only occasionally correlated with the total June–July rainfall. There was a weak positive correlation between FHB incidence and proportion of FDK. There was a strong positive correlation between DS and proportion of FDK. The cultivar affected colonisation of kernels byFusariumspp.Fusarium poaewas the FHB pathogen isolated most often.Fusarium poaecolonised 6.0% of the kernels, on average, but up to 12.0% on individual cultivars. OtherFusariumspecies were less frequent:F. avenaceumin 5.6% of kernels,F. culmorumin 5.3%,F. tricinctumin 2.8%,F. graminearumin 1.5%, andF. sporotrichioidesin 1.2%.Fusarium equisetioccurred sporadically. The importance ofF. poaein the FHB complex is emphasised. All cultivars expressed ‘moderate FHB resistance’ if evaluated according to FHB incidence. Cultivars Arabella, Izera, Kandela, Monsun, Ostka Smolicka, and Struna expressed ‘moderate susceptibility’, and Bombona, Hewilla, Katoda, KWS Torridon, Łagwa, Nawra, Parabola, Radocha, SMH 87, Trappe, Tybalt, and Waluta expressed ‘susceptibility’ if evaluated by the proportion of FDK. Cultivars differed within the ‘moderately resistant’, ‘moderately susceptible’, and ‘susceptible’ categories. Cultivars Arabella, Izera, Kandela, Monsun, Ostka Smolicka, and Struna were the most promising and their resistance traits may be useful in FHB management.

Fusarium head blight (FHB) and Fusarium populations in grain of winter wheat grown in different cultivation systems

Abstract Fusarium head blight (FHB) incidence, and colonisation of grain by Fusarium species on winter wheat grown in organic, integrated, and conventional systems as well as in monoculture, were studied locally in Poland, from 2002 to 2010. Fusarium head blight incidence differed throughout the study years. It was found to occur the most where rainfall was highest and where rainfall was the most prolonged before, during, and after flowering of wheat. Fusarium head blight incidence was generally less on wheat grown organically than on wheat grown in other systems. In some years, FHB was noted more in monocultures than in other systems. Fusarium poae was the most common species of FHB populations in wheat kernels, followed by F. avenaceum and F. tricinctum. Other species which occurred more rarely or sporadically were: F. culmorum, F. equiseti, F. graminearum, F. langsethiae, F. oxysporum, and F. sporotrichioides. There were found to be significant effects of the cropping system on grain colonisation by Fusarium in some years. There was a positive correlation between FHB incidence and number of kernels colonised and damaged by Fusarium, in all four systems. Inferences were drawn concerning the effects of different procedures in different production systems and the possible value for controlling FHB

Bread wheat performance, fusarium head blight incidence and weed infestation response to low-input conservation tillage systems in eastern Canada

Munger, H., Vanasse, A., Rioux, S. and Legere, A. 2014. Bread wheat performance, fusarium head blight incidence and weed infestation response to low-input conservation tillage systems in eastern Canada. Can. J. Plant Sci. 94: 193-201. Bread wheat performance, the incidence of diseases like fusarium head blight (FHB) and weed infestations may be affected by low-input systems and conservation tillage practices. This 2-yr study assessed the effects of three 24-yr-old tillage treatments (MP: moldboard plow; CP: chisel plow; NT: no-till) and two cropping systems (high-input: herbicide and mineral fertilizer; low-input: mechanical weed control and organic fertilizer) on wheat productivity, deoxynivalenol (DON) content, Fusarium graminearum inoculum production, and weed infestation in hard red spring wheat. In 2009, low-input CP and NT yields were 13 and 31% lower, respectively, than low-input MP yield, which was comparable with all of the high-input treatment yields. In 2010, yields were 23% lower in CP and NT ...

Bread wheat performance, fusarium head blight incidence and weed infestation response to low-input conservation tillage systems in eastern Canada

Munger, H., Vanasse, A., Rioux, S. and Légère, A. 2014. Bread wheat performance, fusarium head blight incidence and weed infestation response to low-input conservation tillage systems in eastern Canada. Can. J. Plant Sci. 94: 193–201. Bread wheat performance, the incidence of diseases like fusarium head blight (FHB) and weed infestations may be affected by low-input systems and conservation tillage practices. This 2-yr study assessed the effects of three 24-yr-old tillage treatments (MP: moldboard plow; CP: chisel plow; NT: no-till) and two cropping systems (high-input: herbicide and mineral fertilizer; low-input: mechanical weed control and organic fertilizer) on wheat productivity, deoxynivalenol (DON) content, Fusarium graminearum inoculum production, and weed infestation in hard red spring wheat. In 2009, low-input CP and NT yields were 13 and 31% lower, respectively, than low-input MP yield, which was comparable with all of the high-input treatment yields. In 2010, yields were 23% lower in CP and NT compared with MP, and 32% lower in low-input than in high-input systems. Optimum wheat yield in low-input systems appeared conditional to adequate weed control, which was achieved with MP and CP tillage. Protein content, test weight, and 1000-kernel weight were higher in the high-input system than in the low-input system, except for test weight in 2009. DON content was not affected by tillage in either year, and was lower in low-input system than in high-input system in 2009. Fusarium graminearum inoculum measured in 2009 was similar across tillage treatments in the high-input system, whereas in the low-input system, the inoculum was lower in NT than in MP. In 2010, DON content was not affected by any treatment. Hot and dry conditions were not conducive to pathogen development, and may explain the low level of DON and the lack of treatment effect.

Single and sequential applications of metconazole alone or in mixture with pyraclostrobin to improve Fusarium head blight control and wheat yield in Brazil

Four fungicide trials were conducted in northern RS state during 2009. Six treatments, from the combination of one (flowering = F) or two applications (F + 10 days) of metconazole sprayed alone or in mixture with pyraclostrobin were tested. Fusarium head blight incidence (INC) and severity (SEV) were assessed at the pre-harvest period and Fusarium-damaged kernel (FDK), kernel infection (KI) and deoxynivalenol (DON) and nivalenol (NIV) trichothecenes were quantified on harvested kernels. Disease incidence ranged from 43.8% to 90% and from 7.3% to 31% respectively in the unsprayed check. Both INC and SEV were reduced in all fungicide treatments compared to the check across trials. Levels of FDK and KI were not affected by fungicides where susceptible and moderately resistant cultivars were used, respectively. The fungicide x cultivar susceptibility interaction was significant with the highest severity reduction (>70%) susceptible cultivars. Overall yield increased (+400 kg/ha) in fungicide-treated plots compared to the check; the mixture of fungicides led to higher increase (+275kg/ha) in yield. Yield increased modestly (+150 kg/ha) for two sprays compared to a single spray. Both DON and NIV were found in variable levels across trials but non significant effect of fungicides was found on mycotoxin levels.

A field-specific web tool for the prediction of Fusarium head blight and deoxynivalenol content in Belgium

Fusarium head blight is a worldwide problem in wheat growing areas. In addition to yield loss, Fusarium species can also synthesise mycotoxins and thus threaten animal and human health. Models for predicting Fusarium head blight and deoxynivalenol content in wheat provide farmers with a tool for preventing yield loss and mycotoxin contamination. Growers may use the predictions to underpin decision making on cultivation techniques and the application of fungicides. At the end of the growing season, the food and feed industry may use the predictions to make marketing decisions. Furthermore, the predictions are helpful to identify regions with a higher disease pressure and thus improve sampling efficiency. Based on the data of 3100 wheat samples from 18 locations throughout Belgium between 2002 and 2011, various predictive models were evaluated. The most accurate models were implemented in a web tool to provide growers with field-specific predictions of Fusarium head blight incidence and deoxynivalenol content. The predictions are based on the agronomic variables of a specific wheat field and weather data from the nearest weather station. During the growing season several predictions can be asked. The web tool provides a graphical representation of the predicted results together with an advice on management strategies and recommendations for fungicide application.

Effect of foliar treatments to durum wheat on flag leaf senescence, grain yield, quality and deoxynivalenol contamination in North Italy

Since the production of durum wheat in the drier areas of the Mediterranean Basin is characterized by high variability in terms of yield and grain quality, there is also considerable interest in developing durum wheat in the northern regions, where the pedo-climatic conditions can offer the possibility of obtaining grain yields with higher technological quality and stability. However, the climatic conditions in the northern regions make durum wheat more prone to fungal foliar disease, particularly to Septoria Tritici Blotch ( Septoria tritici Rob.) and to Fusarium Head Blight ( Fusarium graminearum Petch and Fusarium culmorum Sacc.), with the consequent occurrence of DON in grains. Field experiments have been conducted over two growing seasons at four sites in North West Italy to evaluate the effect of fungicides and foliar nitrogen fertilizer application on durum wheat yield and grain quality. Five combinations of foliar application were compared at each site and each year (untreated control, azole fungicide application at heading, strobilurin fungicide at the stem elongation stage and/or at heading, the addition of a foliar N fertilizer to a fungicide programme). The following parameters were analysed: Septoria Tritici Blotch (STB) severity, flag leaf greenness using a chlorophyll meter, grain yield, test weight, grain protein content, ash content, vitreousness, Fusarium Head Blight (FHB) incidence and severity and deoxynivalenol (DON) contamination. The collected data underline that the cultivation of durum wheat at the climatic conditions of North Italy is actually risky and needs a direct control of fungal disease, which would be able to reduce the development of both foliar and head attacks. The double treatment, with a strobilurin application during the stem elongation stage and azole at heading, results to be an essential practice and showed advantages in terms of the delay of flag leaf senescence (+27%), STB control (+31), FHB control (+11%), yield (+32%) and DON contamination (−45%), compared to the untreated control. Other foliar treatments at heading, such as strobilurin or foliar N fertilizer applications, do not seem to provide any further advantage, for either grain yield or quality. No significant effect of fungicide or foliar N fertilizer application was recorded on the protein or ash concentration or vitreousness.

Spring Wheat and Durum Yield and Disease Responses to Copper Fertilization of Mineral Soils

Copper deficiency has been linked to the incidence of a number of wheat diseases. Canadian research on mineral soils has suggested that low Cu availability, as indicated in a DTPA extraction soil test, combined with low soil organic C and coarse textures may also result in Cu deficiency of cereals. The objective of this study was to determine the yield responses of spring wheat (Triticum aestivum L.) and durum [T. turgidum subsp. durum (Desf.) Husn.] to Cu fertilization, and to determine whether wheat leaf rust (Puccinia triticina Roberge ex Desmaz f. sp. tritica), tan spot [Pyrenophora tritica‐repentis (Died.) Dreschler], and Fusarium head blight (Fusarium graminearum Schwabe) incidence and severity would be reduced with these treatments. Experiments were established from 1998–2000 on 17 spring wheat sites and three durum wheat sites throughout North Dakota. Disease ratings were recorded at 10 sites.

Spring Wheat and Durum Yield and Disease Responses to Copper Fertilization of Mineral Soils

Copper deficiency has been linked to the incidence of a number of wheat diseases. Canadian research on mineral soils has suggested that low Cu availability, as indicated in a DTPA extraction soil test, combined with low soil organic C and coarse textures may also result in Cu deficiency of cereals. The objective of this study was to determine the yield responses of spring wheat (Triticum aestivum L.) and durum [T. turgidum subsp. durum (Desf.) Husn.] to Cu fertilization, and to determine whether wheat leaf rust (Puccinia triticina Roberge ex Desmaz f. sp. tritica), tan spot [Pyrenophora tritica-repentis (Died.) Dreschler], and Fusarium head blight (Fusarium graminearum Schwabe) incidence and severity would be reduced with these treatments. Experiments were established from 1998–2000 on 17 spring wheat sites and three durum wheat sites throughout North Dakota. Disease ratings were recorded at 10 sites.

Examination of meteorology-based predictions of Fusarium head blight of wheat grown at two locations in the southern Pampas region of Argentina

In Argentina, head blight or scab is a highly risky disease (caused by Fusarium graminearum) of wheat, although its occurrence is sporadic depending on prevalent environmental variables. These traits stimulated the development of predictive models of head blight epidemics, which would help growers in the selection of control strategies. Regression models for predicting head blight incidence were developed at Pergamino (33°56S, 60°30W), associating temperature and moisture variables with mean disease data (empirical approach). Recently a new fundamental-empirical approach for estimating Fusarium index (incidence%×severity%/100) was developed using data from Pergamino and Marcos Juarez (32°41′S, 62°07′W). Validation studies of both empirical and fundamental-empirical approaches were carried out at northern and southern locations showing good results after making a few changes. The objective of this work was to examine the goodness of fit of the predicted values from both approaches (original and including some of the changes derived from previous validation studies) in comparison with median disease data in two southern locations of the Pampas region: Balcarce (37°45′S, 58°18′W) and Barrow (38°19′S, 60°15′W), for the 2002, 2003 and 2004 wheat seasons. Partial and mean deviation values between observed and predicted data were calculated. In accordance with previous validation studies, successful Fusarium index estimations were achieved decreasing the heat accumulation defining the length of the wheat critical period for infection to 450 degree days [base mean daily temperature (Td)=10°C]. Reducing the critical period length [450 degree days (base Td=0°C) instead of 530] and increasing maximum and minimum temperature thresholds (30° instead of 26°C and 11°C instead of 9°C) of the empirical equation thermal variable led to satisfactory Fusarium incidence predictions. This study showed that both approaches developed at northern locations of the Pampas region can be portable and useful for predicting disease intensity at more southern locations, making only a few changes. Differences in wheat cultivar behaviour regarding the disease were observed in the analysed data but this effect was not considered in this study.

DNA markers associated with low Fusarium head blight incidence and narrow flower opening in wheat

Fusarium head blight (FHB) of wheat, caused by Fusarium graminearum, is an important fungal disease in many wheat-growing areas of the world. The objectives of this study were to determine the relationship between width and duration of flower opening and incidence of FHB in wheat, and to identify DNA markers associated with narrow flower opening and low FHB incidence. It was hypothesized that wheat lines whose flowers open briefly and narrowly have a reduced risk of infection. To test the hypothesis, we crossed wheat cultivars Patterson and Goldfield to generate a population of 100 random F(2)-derived recombinant inbred lines (RILs). Florets of Patterson open wide; florets of Goldfield tend to stay closed. The population of RILs was characterized for FHB incidence and flower opening width (FOW) and duration in the F(7:9) and F(7:10) generations. Of the 305 simple sequence repeat primer pairs screened on the parents, 79 amplified polymorphic DNA bands. Pooled DNA from each of the two bulks was tested with these 79 SSR primer pairs. Four markers were found to have significant marker-trait association with low FHB incidence and narrow flower opening. The major QTL effect associated with narrow flower opening and low FHB incidence was found between the map interval Xbarc200-Xgwm210, explaining 29% of the phenotypic variation for FHB incidence averaged over six replicated tests in Indiana in 2002 and 2003. This adds credence to the hypothesis that narrow flower opening is responsible for low FHB incidence in this population. Breeding wheat lines for both morphological avoidance, such as narrow flower opening, and physiological resistance to FHB may be valuable in future breeding research to reduce crop production and grain quality losses in wheat due to FHB.

Fusarium Head Blight and Deoxynivalenol Accumulation of Barley in Eastern Canada: Cultivar Response and Correlation Analysis

Fusarium head blight of barley (Hordeum vulgare) is a devastating disease in many countries. We undertook a study to identify barley cultivars, if any, that are resistant to Fusarium head blight and deoxynivalenol (DON) accumulation and to determine if DON concentration is correlated with other plant traits in Eastern Canada and China. Barley cultivars were grown in the field under artificial inoculation conditions at two locations (Charlottetown and Ottawa) in Canada during two summers and at Hangzhou in China during two winters. Seed samples were collected for DON analysis from the barley performance trial at five locations in Ontario. None of the 64 barley cultivars were immune to Fusarium head blight infection. Two-row cultivars, however, were significantly more resistant to Fusarium head blight infection and DON accumulation than six-row cultivars. Three cultivars (Island, AC Alberte, and Chevron) were found to be most resistant, as they were consistently low in Fusarium head blight incidence and DON concentration in both Eastern Canada and China. In six-row barley, DON concentration was correlated positively with Fusarium head blight incidence at both Charlottetown and Ottawa, and it was negatively correlated with plant height at Ottawa. DON concentration and heading date were not consistently correlated. Barley yellow dwarf and powdery mildew appeared to have very little effect on Fusarium head blight infection. Susceptibility to DON accumulation did not result in low yield under natural infection conditions in Ontario. Cultivar × location interactions for DON concentration, Fusarium head blight incidence, and heading date were significant.

Meteorological-Based Predictions of Wheat Head Blight Epidemic in the Southern Argentinean Pampas Region

In Argentina, head blight is a highly risky disease (caused by Fusarium graminearum), although its occurrence is sporadic depending on prevalent environmental variables. These traits stimulated the development of predictive models of head blight occurrence which would help growers in the selection of control strategies. Empirical equations for predicting head blight incidence were developed at Pergamino (33° 56′ S, 60° 30′ W) associating temperature and moisture variables with mean disease data. Recently a new fundamental-empirical approach for estimating Fusarium index (incidence% x severity%/100) was developed using data of Pergamino and Marcos Juarez (32° 41′ S, 62°07′ W). In this study our objective was to validate both approaches at three more southern locations: La Dulce (38° 10′ S, 58° 00′ W), Miramar (38° 00′ S, 57° 33′ W) and Balcarce (37° 45′ S, 58° 18W), for the 2001 crop season. Examining partial and mean deviation values between observed and predicted incidence data, an underestimation especially at La Dulce was assessed. A clear improvement of incidence goodness of fit estimations was obtained decreasing the heat accumulation defining the length of the wheat critical period for infection. Employing this last critical period length for the fundamental-empirical approach led to satisfactory Fusarium index predictions. This study showed that both approaches developed at northern locations of the Pampas region can be portable and useful for predicting disease intensity at more southern locations, making only a few changes.