Choice of fungicide seed treatment solution composition affecting dust emission from cereal crop seeds

Die Entstehung von Beizstaub stellt eine potentielle Verlustquelle fungizider Beizmittel dar und kann darüber hinaus eine unbewusste Quelle für die Freisetzung von Chemikalien gegenüber Nichtziel-Organismen und Anwendern bilden. In der vorliegenden Studie wurde eine Bewertung der Staubemission durch die Verwendung von verschiedenen Beizlösungszusammensetzungen (mit und ohne Additiv) anhand verschiedener Aufwandmengen und unterschiedlichem Saatgut durchgeführt. Nach der Verwendung eines standardisierten Behandlungsprotokolls wurde die Probenlagerung für eine definierte Zeit durchgeführt, woraufhin anschließend eine Staubmessung mittels Heubach-Dustmeter erfolgte. Je nach Verwendung von Additiven wurden verschiedene Staubemissionen nachgewiesen. Eine Gesamtreduktion des Staubniveaus wurde durch die Anwendung von Additiven im Vergleich zur alleinigen Verwendung von Saatgutbehandlungsmitteln gezeigt.Seed dust emission in small grain cereals is a possible loss path for fungicidal seed dressing and furthermore a source of unrecognized release of chemicals towards non target organisms and users. In the present study, an evaluation of dust emission was conducted due to the use of different slurry solution composition (with and without adjuvant), using different application rates and crop seeds. After using a standardized treatment protocol, sample storage was conducted for an appropriate defined time until dust measurement by Heubach-dustmeter was carried out. Different levels of dust were detected according to the use of adhesive adjuvants. An overall reduction of dust level was achieved by the application of adjuvants compared to the single use of seed dressings

Impact of adhesive adjuvants addition into seed treatments on the flowability of cereal crop seeds

Das Fließverhalten von Schüttgütern wird durch das Material der Oberfläche beeinflusst. Die Applikation von Saatgutbehandlungsmitteln führt zu einer Änderung der Grenzreibung zwischen einzelnen Getreidekörnern als Folge von Kontakt. In der vorliegenden Studie wurde ein Vergleich zwischen verschiedenen Beizlösungen, mit und ohne Additiv in Bezug auf die Fließfähigkeit durchgeführt. Es konnten, abhängig von den eingesetzten Zusatzpräparaten unterschiedliche Effekte detektiert werden. Die Verwendung von pflanzenölbasierten Adjuvantien Kantor® und Inteco® in Kombination mit den Saatgutbehandlungsmitteln EfA® und Rubin®TT reduzierte die Energiefreisetzung, verglichen mit der jeweiligen Varianten ohne Additiv, anhand der Verwendung von Weizen-, Gerste-, Roggen-, Hafer und Triticalesaatgut. Im Gegensatz dazu erhöhte die Zugabe des Polysiloxan-basierten Additivs MaximalFlow® die Energiefreisetzung in 70% aller Vergleiche, relativ zur Variante ohne Zusatz.Flow behavior of bulk material is influenced by surface material. The application of different seed treatment slurries indicate a change of boundary friction between the grains as a result of contact. A comparison between adjuvant added and single treated cereal seed was conducted in the present study to evaluate the impact on flowability. Related to the chemical components of the used adjuvants different impacts were detected. The use of plant oil based adjuvants Kantor® and Inteco® reduced the value of released energy compared to single use of seed treatments EfA® and Rubin®TT in crop seeds wheat, barley, rye, oat and triticale at 80% of treatments. Contrary to this, the addition of a polysiloxane based adjuvant MaximalFlow® increased the value of released energy representing flowability in 70% of treatments compared to single use of preparatio

Will Triazoles Still Be of Importance in Disease Control of Zymoseptoria tritici in the Future?

Septoria tritici blotch (STB), caused by Zymoseptoria tritici, is one of the most important foliar wheat diseases worldwide. Current control strategies of STB rely mainly on fungicides, whereby triazoles (demethylation inhibitors; DMIs) have been the backbone in the control of Z. tritici in the last decades. However, in recent years a gradual loss of sensitivity of Z. tritici to several active ingredients of the triazole group has been reported in several European wheat-growing areas. Nevertheless, a new triazole fungicide, namely, mefentrifluconazole, has recently become available in disease management of STB, which belongs to a completely new triazole subclass, the so-called isopropanol triazoles. In this study, the trend in sensitivity development of Z. tritici towards older triazoles (tebuconazole, prothioconazole, and propiconazole) and the new isopropanol triazole mefentrifluconazole was determined in microtiter assays using Z. tritici field populations isolated in 1999, 2009, 2014, and 2020 in a high-disease-pressure and high-fungicide-input area in northern Germany in order to investigate whether the loss of sensitivity of Z. tritici to older triazoles also applies to mefentrifluconazole. For the three triazole fungicides tebuconazole, prothioconazole and propiconazole, a significant shift towards decreasing sensitivity of Z. tritici field populations was observed from 1999 to 2020, whereas the efficacy of mefentrifluconazole in reducing the in vitro fungal growth by 50% (EC50) remained unchanged over the investigated period, demonstrating a stable sensitivity of Z. tritici towards mefentrifluconazole. Although older triazoles are suffering from a loss of sensitivity of Z. tritici field populations due to the selection and spread of less triazole sensitive strains within the Z. tritici population, the efficacy of the new triazole mefentrifluconazole with its unique isopropanol unit was not affected by these changes within the Z. tritici population. Thus, the introduction of such new molecular units could also represent an important contribution for older groups of active ingredients, which previously suffered from a loss of sensitivity

Composition and Predominance of Fusarium Species Causing Fusarium Head Blight in Winter Wheat Grain Depending on Cultivar Susceptibility and Meteorological Factors

Fusarium head blight (FHB) is one of the most important diseases of wheat, causing yield losses and mycotoxin contamination of harvested grain. A complex of different toxigenic Fusarium species is responsible for FHB and the composition and predominance of species within the FHB complex are determined by meteorological and agronomic factors. In this study, grain of three different susceptible winter wheat cultivars from seven locations in northern Germany were analysed within a five-year survey from 2013 to 2017 by quantifying DNA amounts of different species within the Fusarium community as well as deoxynivalenol (DON) and zearalenone (ZEA) concentrations. Several Fusarium species co-occur in wheat grain samples in all years and cultivars. F. graminearum was the most prevalent species, followed by F. culmorum, F. avenaceum and F. poae, while F. tricinctum and F. langsethiae played only a subordinate role in the FHB complex in terms of DNA amounts. In all cultivars, a comparable year-specific quantitative occurrence of the six detected species and mycotoxin concentrations were found, but with decreased DNA amounts and mycotoxin concentrations in the more tolerant cultivars, especially in years with higher disease pressure. In all years, similar percentages of DNA amounts of the six species to the total Fusarium DNA amount of all detected species were found between the three cultivars for each species, with F. graminearum being the most dominant species. Differences in DNA amounts and DON and ZEA concentrations between growing seasons depended mainly on moisture factors during flowering of wheat, while high precipitation and relative humidity were the crucial meteorological factors for infection of wheat grain by Fusarium. Highly positive correlations were found between the meteorological variables precipitation and relative humidity and DNA amounts of F. graminearum, DON and ZEA concentrations during flowering, whereas the corresponding correlations were much weaker several days before (heading) and after flowering (early and late milk stage)

Temporal Changes in Sensitivity of Zymoseptoria tritici Field Populations to Different Fungicidal Modes of Action

Septoria tritici blotch (STB; Zymoseptoria tritici), one of the most important foliar diseases in wheat, is mainly controlled by the intensive use of fungicides during crop growth. Unfortunately, Z. tritici field populations have developed various extents of resistance to different groups of fungicides. Due to the complete resistance to quinone outside inhibitors (QoIs), fungicidal control of STB relies mainly on demethylation inhibitors (DMIs) and succinate dehydrogenase inhibitors (SDHIs) as well as multi-site inhibitors. In this study, temporal changes in the sensitivity of Z. tritici to selected DMIs (tebuconazole, propiconazole, prothioconazole, prochloraz), SDHIs (boscalid, bixafen), and multi-site inhibitors (chlorothalonil, folpet) were determined in microtiter assays using Z. tritici field populations isolated in 1999, 2009, 2014, and 2020 in a high-disease-pressure and high-fungicide-input area in Northern Germany. For the four tested DMI fungicides, a significant shift towards decreasing sensitivity of Z. tritici field populations was observed between 1999 and 2009, whereby concentrations inhibiting fungal growth by 50% (EC50) increased differentially between the four DMIs. Since 2009, EC50 values of tebuconazole, propiconazole, and prochloraz remain stable, whereas for prothioconazole a slightly increased sensitivity shift was found. A shift in sensitivity of Z. tritici was also determined for both tested SDHI fungicides. In contrast to DMIs, EC50 values of boscalid and bixafen increased continuously between 1999 and 2020, but the increasing EC50 values were much smaller compared to those of the four tested DMIs. No changes in sensitivity of Z. tritici were observed for the multi-site inhibitors chlorothalonil and folpet over the last 21 years. The sensitivity adaptation of Z. tritici to both groups of single-site inhibitors (DMIs, SDHIs) mainly used for STB control represents a major challenge for future wheat cultivation

Spatio-Temporal Prediction of the Epidemic Spread of Dangerous Pathogens Using Machine Learning Methods

Real-time identification of the occurrence of dangerous pathogens is of crucial importance for the rapid execution of countermeasures. For this purpose, spatial and temporal predictions of the spread of such pathogens are indispensable. The R package papros developed by the authors offers an environment in which both spatial and temporal predictions can be made, based on local data using various deterministic, geostatistical regionalisation, and machine learning methods. The approach is presented using the example of a crops infection by fungal pathogens, which can substantially reduce the yield if not treated in good time. The situation is made more difficult by the fact that it is particularly difficult to predict the behaviour of wind-dispersed pathogens, such as powdery mildew (Blumeria graminis f. sp. tritici). To forecast pathogen development and spatial dispersal, a modelling process scheme was developed using the aforementioned R package, which combines regionalisation and machine learning techniques. It enables the prediction of the probability of yield- relevant infestation events for an entire federal state in northern Germany at a daily time scale. To run the models, weather and climate information are required, as is knowledge of the pathogen biology. Once fitted to the pathogen, only weather and climate information are necessary to predict such events, with an overall accuracy of 68% in the case of powdery mildew at a regional scale. Thereby, 91% of the observed powdery mildew events are predicted

Can Decision Support Systems Help Improve the Sustainable Use of Fungicides in Wheat?

Wheat is one of the most economically important field crops worldwide. Foliar diseases are a major threat to wheat productivity and are primarily managed by implementing less susceptible cultivars and using fungicides. With the “Farm to Fork” strategy under consideration by the European Union to reduce pesticide usage by 50% by 2030, this elucidates the importance of utilizing decision support systems (DSS) to optimize fungicide applications. Therefore, three DSSs of different origins, namely the IPM-Wheat Model Schleswig-Holstein (scientific), the ISIP system (federal), and the xarvio© FIELD MANAGER (commercial), were analysed under maritime climate conditions at three locations in a high input area of wheat cultivation in northern Germany from 2019 to 2021. Fungicide efficacy was evaluated for yield as well as for the management of prevalent pathogens (Septoria tritici blotch, glume blotch, tan spot, powdery mildew, stripe rust, and leaf rust) on two different commercially available cultivars (highly and moderately susceptible). Compared to a stage-oriented standard system, no significant decrease in yield was observed in both cultivars, despite up to a 50% reduction in fungicide use through the use of DSSs. This was attributed to an optimized timing of fungicide applications, which resulted in slightly lower but still tolerable disease suppression efficacy compared to the stage-oriented system. In conclusion, minor disease severities are often overestimated, and DSSs can help improve the sustainability of fungicide use in wheat and pesticides in general

Confirmation of an ALS-resistant Lolium perenne population in Northern Germany

Auf einem Ackerschlag im Östlichen Hügelland Schleswig-Holsteins wurde in der Vergangenheit eine Fruchtfolge aus Wintergerste, Winterraps und Winterweizen in einer wiederkehrenden dreijährigen Frucht­folge angebaut. Im Herbst und Frühjahr 2014/15 wurden in eigenen Untersuchungen erstmals deutliche Bekämpfungsprobleme von Deutschem Weidelgras (Lolium perenne) auf dieser Ackerfläche dokumentiert. Aufgrund dieser Beobachtungen und dem Einsatz gleicher Wirkstoffe in den vergangenen Jahren wurde die Verdachtspopulation auf eine etwaige Resistenz getestet. Nach einer Pflanzenprobenahme im Frühjahr 2015 und sich anschließenden Wirkungsversuchen unter Gewächshausbedingungen mit verschiedenen Dosierungen von Wirkstoffen aus der Gruppe der ACCase- und ALS-Inhibitoren sowie einer molekularen Resistenzanalyse steht fest, dass in Schleswig-Holstein eine bis jetzt noch nicht näher betrachtete ALS-resistente Spezies bestätigt werden konnte. Es zeigte sich bei der Verdachtspopulation neben einer ausgeprägten Resistenz gegenüber ALS-Inhibitoren eine vermutlich zusätzliche metabolische Resistenz in Form von ersten Wirkungsverlusten gegenüber Aryloxyphenoxy-propionaten und Clethodim. DOI: 10.5073/JfK.2016.05.01, https://doi.org/10.5073/JfK.2016.05.01In the east of Schleswig-Holstein, in the recent years on a farmland were grown winter barley, winter oilseed rape and winter wheat in a three-year crop rotation. In autumn and spring 2014/15, severe problems to control perennial ryegrass (Lolium perenne) were recognized for the first time in field-trials. Based on these observations and the use of the same herbicides in recent years, the suspect population was tested for a possible herbicide resistance. After a plant sampling in the spring of 2015 and subsequent greenhouse bioassays with different doses of ACCase and ALS inhibitors, followed by a molecular resistance testing, a hitherto unknown ALS-resistant weed species was confirmed in Schleswig-Holstein. In addition to a marked resistance to ALS inhibitors, a poten­tial metabolic resistance in the form of first effect losses against aryloxyphenoxy-propionates and cle­thodim was observed in the suspect population. DOI: 10.5073/JfK.2016.05.01, https://doi.org/10.5073/JfK.2016.05.0

Occurrence of Fusarium Mycotoxins and Their Modified Forms in Forage Maize Cultivars

Forage maize is often infected by mycotoxin-producing Fusarium fungi during plant growth, which represent a serious health risk to exposed animals. Deoxynivalenol (DON) and zearalenone (ZEN) are among the most important Fusarium mycotoxins, but little is known about the occurrence of their modified forms in forage maize. To assess the mycotoxin contamination in Northern Germany, 120 natural contaminated forage maize samples of four cultivars from several locations were analysed by liquid chromatography-high resolution mass spectrometry (LC-HRMS) for DON and ZEN and their modified forms deoxynivalenol-3-glucoside (DON3G), the sum of 3- and 15-acetyl-deoxynivalenol (3+15-AcDON), α- and β-zearalenol (α-ZEL, β-ZEL). DON and ZEN occurred with high incidences (100 and 96%) and a wide range of concentrations, reaching levels up to 10,972 and 3910 µg/kg, respectively. Almost half of the samples (46%) exceeded the guidance value in complementary and complete feeding stuffs for ZEN (500 µg/kg), and 9% for DON (5000 µg/kg). The DON related mycotoxins DON3G and 3+15-AcDON were also present in almost all samples (100 and 97%) with amounts of up to 3038 and 2237 µg/kg and a wide range of concentrations. For the ZEN metabolites α- and β-ZEL lower incidences were detected (59 and 32%) with concentrations of up to 423 and 203 µg/kg, respectively. Forage maize samples were contaminated with at least three co-occurring mycotoxins, whereby 95% of all samples contained four or more mycotoxins with DON, DON3G, 3+15-AcDON, and ZEN co-occurring in 93%, together with α-ZEL in 57% of all samples. Positive correlations were established between concentrations of the co-occurring mycotoxins, especially between DON and its modified forms. Averaged over all samples, ratios of DON3G/DON and 3+15-AcDON/DON were similar, 20.2 and 20.5 mol%; cultivar-specific mean ratios ranged from 14.6 to 24.3 mol% and 15.8 to 24.0 mol%, respectively. In total, 40.7 mol% of the measured DON concentration was present in the modified forms DON3G and 3+15-AcDON. The α-ZEL/ZEN ratio was 6.2 mol%, ranging from 5.2 to 8.6 mol% between cultivars. These results demonstrate that modified mycotoxins contribute substantially to the overall mycotoxin contamination in forage maize. To avoid a considerable underestimation, it is necessary to analyse modified mycotoxins in future mycotoxin monitoring programs together with their parent forms

Efficiency and Effectivity of a Biological–Epidemiological Fungal Disease Management System in Wheat—A Study of 26 Years

Foliar diseases are a major threat to worldwide wheat production, especially during the vegetative period in maritime climates. Despite advancements in agronomic practices, infestations by foliar diseases are possible under favourable weather conditions, thus, fungicides are essential for maintaining control. Stage-oriented applications are therefore common in farm practices. The optimization of fungicide use according to biological–epidemiological thresholds reduces the total amount of fungicides used, which is of political interest, especially in the European Union. Therefore, the efficiency and effectivity of the fungicides used to control the six major foliar diseases (Septoria tritici blotch, glume blotch, tans spot, powdery mildew, stripe rust, and leaf rust) were analysed in a long-term study of 26 years in northern Germany under favourable maritime conditions. Of those diseases, Septoria tritici blotch was the most dominant recurring disease, with high severity noted in every year of the study. The threshold-based disease management system was compared to a fungicide untreated control and a healthy-standard fungicide treatment (according to growth stages). The usage of the threshold-based system reduced the disease severities significantly compared to the fungicide untreated control, without any loss of yield compared to the healthy-standard fungicide treatment. Thereby, the use of fungicides was reduced by two thirds compared to the stage-oriented healthy-standard treatment. Thus, the advantages of the threshold-based system were obvious, and this approach will be an important tool for future evaluations of current farm practices