Integrating the impact of wheat fungal diseases in the Belgian crop yield forecasting system (B-CYFS)

in European Journal of Agronomy (2012), 40

Field experiments were conducted over four growing seasons to assess the relationship between fungal disease attacks and wheat grain yield in the agrometeorological part of the Belgian crop yield ... [more ▼]

Field experiments were conducted over four growing seasons to assess the relationship between fungal disease attacks and wheat grain yield in the agrometeorological part of the Belgian crop yield forecasting system (i.e., Belgian crop growth monitoring system, B-CGMS) by recalibrating the lifespan of wheat leaves (SPAN parameter). The results from 133 experimental fields in Belgium (the Wallonia region) and the Grand-Duchy of Luxembourg were analyzed in terms of site factors such as cultivar, previous crop, sowing date and geographical area. A significant relationship was found between green leaf area (GLA) duration expressing the infection pressure (parameter m; using a modified Gompertz model and calculated from observed GLA) and final grain yield (R2 = 0.79; P < 0.001). Based on this relationship and by recalibrating the B-CGMS in terms of its SPAN parameter, there was a significant improvement in estimating final grain yield. From a R2 of 0.11 when the B-CGMS was run with the default SPAN value, the relationship between observed and simulated yields was strengthened, with a R2 of 0.47 and 0.57, respectively, when a linear or quadratic relationship was considered between m and SPAN. Although, from a practical point of view, the m value has to be estimated annually for each spatial grid or group of grids on the basis of field or possibly remotely sensed data, and although estimating this parameter is possible only late in the season, these encouraging results illustrate the potential of integrating pest and disease impact in the B-CGMS. [less ▲]

Maladies du blé d'hiver au Luxembourg Les interactions entre climat, sol et phytotechnie montrent l'importance primordiale du facteur climat

in Phytoma : La Défense des Végétaux (2012), 650

Malgré sa petite taille, le GDL est caractérisé par deux régions très contrastées en ce qui concerne les maladies cryptogamiques du blé d’hiver. Une analyse en composante principale a permis d’analyser la ... [more ▼]

Malgré sa petite taille, le GDL est caractérisé par deux régions très contrastées en ce qui concerne les maladies cryptogamiques du blé d’hiver. Une analyse en composante principale a permis d’analyser la distribution des maladies cryptogamiques entre le Gutland et l’Oseling. La distribution des maladies cryptogamiques est significativement différente (P < 0.001) entre le Gutland et l’Oesling. Entre 2003 et 2009, la septoriose et la rouille brune sont des maladies qui caractérisent le Gutland avec respectivement comme pourcentage 51 et 17%. Dans l’Oesling, la sévérité de ces maladies était très faible et n’atteignait même pas 1%. A l’opposé, l’Oesling est caractérisée par l’installation de l’Oïdium surtout en 2003 et 2009 avec respectivement 15 et 40% de sévérité alors cette maladie ne dépassait pas 1% de sévérité en Gutland. Parallèlement à ces maladies, d’autres pathogènes fongiques sont observées uniquement en Gutland et les maladies qu’ils causent sont influencées par la phytotechnie. Il s’agit de l’helminthosporiose et de la rouille jaune avec comme caractéristique le contournement du gène de résistance Yr 17+. La variation dans l’expression des maladies cryptogamiques entre le Gutland et l’Oesling est surtout due aux différences marquées des conditions climatiques entre les deux régions mais aussi aux pratiques agricoles en vigueur (fumure azotée, choix variétal, semis avec labour ou sans labour….). [less ▲]

Spatial and temporal propagation of Cryptosporidium and Giardia at various scales in a drinking water reservoir

Conference (2011, September)

Cryptosporidium and Giardia are emergent protozoan parasites of faecal origin causing diarrhoeal diseases throughout the world. Their impact on public health is closely linked to the management of water ... [more ▼]

Cryptosporidium and Giardia are emergent protozoan parasites of faecal origin causing diarrhoeal diseases throughout the world. Their impact on public health is closely linked to the management of water resources and both pathogens are continuously released in the environment by punctual and diffuse faecal pollution sources. With the amendment of the Water Safety Plans published by the World Health Organization in 2005, the assessment of the public health risk associated with the presence of both parasites has extended to watershed scale. In Luxembourg, the Upper-Sûre reservoir provides 50% of the population of the country with drinking water. The presence of both Cryptosporidium and Giardia in surface water within the catchment area has been documented earlier. The aim of this study was therefore to understand the propagation of both protozoans within the catchment area over time and space. Integrated into a risk assessment-based approach, the results are intended for establishing an efficient monitoring strategy. Currently, no such strategy is available for water utilities. Though it is a crucial tool for improving the management of drinking water resources because it should alert responsible authorities in case of high contamination risk and prevent from possible waterborne outbreaks. [less ▲]

Performance of leaf wetness sensor used in winter wheat disease management

Poster (2011, May 26)

Wetness on crop leaves has particular epidemiological significance because many fungal diseases affect plants only when free moisture is present on leaves. The leaf wetness sensor detects the presence of ... [more ▼]

Wetness on crop leaves has particular epidemiological significance because many fungal diseases affect plants only when free moisture is present on leaves. The leaf wetness sensor detects the presence of wetness on a leaf’s surface, enabling researchers and producers to forecast disease and protect plant canopies, and consequently to optimize fungicide application and often reduce environmental load. This research project aimed at better understanding the leaf wetness duration and its influence in winter wheat disease. Measurement of surface wetness duration by three electronic flat-plate sensors (Model 237-Campbell Scientific, Inc) in wheat fields were compared with tactile and visual observations in replicated field experiments at the site of Arlon (Belgium) during the period May-July 2006 and April-July 2007. Performances of the sensor were evaluated against SWEB model outputs and visual observations of disease symptoms. On the field, dew-onset and dry-off of wetness on leaves were observed visually (with a flash light for dew-onset) at 15-minute intervals. Each sensor was placed close the flag leaf. For the three sensors, the two dew-onset and dry-off times measured in both 2006 and 2007 crop seasons gave a leaf wetness duration (LWD) which was on average one hour less than visual observations. In order to establish a relationship between the surface wetness periods and wheat foliar diseases, LWD was compared with the Septoria leaf blotch (SLB) development risk (main winter wheat disease). A minimal surface wetness duration favourable to infection for SLB was established. [less ▲]

Site-specific Septoria Leaf Blotch Risk Assessment in Winter Wheat using Weather-Radar Rainfall Estimates

in Plant Disease (2011), 10.1094/PDIS-07-10-0482

The Septoria leaf blotch prediction model PROCULTURE was used to assess the impact on simulated infection rates when using rainfall estimated by radar instead of rain gauge measurements. When comparing ... [more ▼]

The Septoria leaf blotch prediction model PROCULTURE was used to assess the impact on simulated infection rates when using rainfall estimated by radar instead of rain gauge measurements. When comparing infection events simulated by PROCULTURE using radar- and gauge-derived data, the probability of detection (PODs) of infection events was high (0.83 on average), and the false alarm ratio (FARs) of infection events was not negligible (0.24 on average). For most stations, FARso of infection events decreased to 0 and PODso increased (0.85 on average) when the model outputs for both datasets were compared against visual observations of disease symptoms. An analysis of 148 infection events over three years at four locations showed no significant difference in the number of infection events of simulations using either dataset, indicating that, for a given location, radar estimates were as reliable as rain gauges for predicting infection events. Radar also provided better estimates of rainfall occurrence over a continuous space than weather station networks. The high spatial resolution provides radar with an important advantage that could significantly improve existing warning systems. [less ▲]

Regional-based typology of the main fungal diseases affecting winter wheat in the Grand-Duchy of Luxembourg

in Phytopathology (2011), 101

Despite its small territory size, the Grand-Duchy of Luxembourg (GDL) has several microclimates that result in a variability of disease severity between the South (Gutland) and the North (Oesling ... [more ▼]

Despite its small territory size, the Grand-Duchy of Luxembourg (GDL) has several microclimates that result in a variability of disease severity between the South (Gutland) and the North (Oesling). Septoria leaf blotch disease of wheat is an important disease in the GDL. Over 2003–2009, the severity was strong in Gutland (51% on average over the last two upper leaves at the late milk growth stage) and low in the Oesling (16% for the same leaves). For the years 2006, 2008 and 2009, the disease severity was less than 6% in the Oesling while it exceeded 40% in the Gutland. The second fungal disease that has become economically important is the wheat leaf rust. Over the same period, the Gutland and the Oesling showed consistently the highest and lowest disease severity respectively. In 2003 and 2007, the Gutland showed the highest disease severity with 66% and 57% respectively, whereas the lowest severity (<1%) was observed in the Oesling. Another important disease is wheat powdery mildew. The 2003 and 2009 cropping seasons showed the highest disease severity with 15% and 40%, respectively, in the Oesling whereas less than 1% severity was registered in the Gutland. Fusarium head blight was also present in the eastern part of the Gutland showing the highest prevalence and severity in 2007 and 2008 (8.5% and 8.3% respectively). These prevalence and severity percentages were significantly higher compared to the Oesling (% prevalence % severity, p = 0.049 and p = 0.012, respectively, Tukey’s test). [less ▲]

Sensitivity of simulated surface wetness duration to meteorological variations in three different regions of Grand-Duchy of Luxembourg

Poster (2010, November 23)

Surface wetness duration (SWD) is an important factor influencing the occurrence of winter wheat diseases. For this reason, SWD is extremely important for the management of crop protection activities. In ... [more ▼]

Surface wetness duration (SWD) is an important factor influencing the occurrence of winter wheat diseases. For this reason, SWD is extremely important for the management of crop protection activities. In order to understand the SWD variability and its influence on winter wheat disease, the objective of this study was to (i) determine the sensitivity of our model on varying input plant parameters and (ii) to evaluate the influence of simulated SWD to meteorological variations in three different climatic regions of the Grand-Duchy of Luxembourg (EVERLANGE, OBERCORN and SCHIMPACH). In this work, an agrometeorological model known as the Surface Wetness Energy Balance (SWEB) was applied for the simulation of SWD. The model was previously applied in another study for winter wheat cultivars and was adapted for use with agrometeorological data easily available from standard meteorological monitoring stations. Based on weather data and simulated SWD data, sensitivity analyses were performed to compare the effects of relative humidity, air temperature, wind speed and net radiation on wetness duration over one growing season (March-July) at three test sites. The results indicated that the sensitivities were very similar at three sites and there was no spatial trend (i.e. difference between locations) in the sensitivities. However, the model is most sensitive to relative humidity and differences between 0.5 and 25 h (per month) SWD were found when increasing/decreasing relative humidity by 10%. The model was least sensitive to changes in air temperature, showing differences of only 0.5–2 h (per month) in SWD. Intermediate sensitivity is found for rainfall, net radiation and wind speed. Among the input plant parameters values, SWD was most sensitive to the maximum fraction of canopy allowed as wet surface area, leaf area index, maximum water storage per unit area and least sensitive to crop height. The sensitivity to parameter values was less important compared to the sensitivity to the meteorological variable relative humidity. [less ▲]

A SIMPLIFIED APPROACH FOR WHEAT YIELD ESTIMATES BASED ON METRICS DERIVED FROM GREEN AREA INDEX DECREASING CURVES.

Poster (2010, September)

Spatial heterogeneity of leaf wetness duration in winter wheat canopy and its influence on plant disease epidemiology

in Phytopathology (2010)

Leaf wetness duration (LWD) is an important factor influencing the occurrence of plant disease epidemiology. Despite considerable efforts to determine LWD, little attention has been given to study its ... [more ▼]

Leaf wetness duration (LWD) is an important factor influencing the occurrence of plant disease epidemiology. Despite considerable efforts to determine LWD, little attention has been given to study its variability within the canopy. The objective of this study was to evaluate its spatiotemporal variability in wheat fields in a heterogeneous landscape. The spatiotemporal variability of LWD was evaluated in a site close to Arlon (Belgium) during the period May to July 2006 and 2007. LWD measurements were made using a set of flat plate sensors deployed at five different distances from a 18 m high hedge (5, 10, 20, 50, 100 m). Each set of two sensors was placed horizontally close the flag leaf. In addition, we collected the amount of dew water that deposited on rigid epoxy plates placed next to each sensors. Experimental results showed that LWD measurements revealed substantial heterogeneity among sensor positions. LWD is longer for sensors closer to the hedge mainly because of its shadowing effect. 3 to 4 hours of difference was observed between sensors located at 5 m and those located at 100 m, and besides, a significant quantitative difference (p < 0.0001) of dew deposit was observed between area beside hedge and those placed at 100 m. In summary, this study provides new information on how wetness is distributed on wheat leaves according to the distance from a hedge. This leads to local microclimate conditions that will contribute to the disease spatial heterogeneity. [less ▲]

Spatial Heterogeneity of Leaf Wetness Duration in Winter Wheat Canopy and Its Influence on Plant Disease Epidemiology.

in Phytopathology (2010)

The leaf wetness duration (LWD) is one of the most important factors influencing the occurrence of plant diseases epidemiology. Despite considerable efforts to determine LWD, little attention has been ... [more ▼]

The leaf wetness duration (LWD) is one of the most important factors influencing the occurrence of plant diseases epidemiology. Despite considerable efforts to determine LWD, little attention has been given to studies its variability in the canopy. The objective of this study was to evaluate the spatio-temporal variability in the field sites cultivated in a heterogeneous landscape. The spatial-temporal variability of LWD was evaluated in winter wheat canopy close to the hedge at Arlon (Belgium) during the period May to July 2006 and 2007. LWD measurements were made using flat plate sensors deployed at five different distances from the hedge (5, 10, 20, 50, 100 m). Each set of two sensors was placed horizontally close the flag leaf (L1) facing north. Parallel to these qualitative measures of wetness we made samples of the quantity of dew deposited on rigid epoxy plates (75 x 60 mm) placed next to each set of sensors (two plates per sensor and sampling). Experimental results show that the LWD measurements revealed substantial heterogeneity among sensors positions. LWD is longer for the sensors located at distance proximate the hedge. Three to four hours of difference was observed between sensors located at 5 m and those located at 100 m, and besides, a significant quantitative difference (p<0.0001) of dew deposit was observed between area beside hedge and those placed at 100m. In summary, this study gives a good idea of how wetness appears at the different range of the hedge. So the diversity of situations favor occurrence of very local microclimate conditions that may initiate disease in specific locations of the plot and not in others. [less ▲]