Entwicklung eines integrierten Behandlungskonzeptes für die Kabatiella-Augenfleckenkrankheit (Kabatiella zeae) und die Turcicum-Blattdürre (Setosphaeria turcica) im Mais (Zea mays subsp. mays L.)
Development an integrated treatment concept for Northern corn leaf blight (Setosphaeria turcica) and Kabatiella eyespot (Kabatiella zeae) in maize (Zea mays subsp. mays L.)
by Sebastian Streit
Date of Examination:2024-11-27
Date of issue:2025-01-20
Advisor:Prof. Dr. Andreas von Tiedemann
Referee:Prof. Dr. Andreas von Tiedemann
Referee:Prof. Dr. Mark Varrelmann
Sponsor:Bundesministerium für Ernährung und Landwirtschaft (BMEL) - Förderkennzeichen 22031215
Sponsor:Energie- und Klimafonds (EFK)
Sponsor:Fachagentur Nachwachsende Rohstoffe e. V. (FNR)
(beliehener Projektträger)
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Abstract
English
The aim of this study was to develop an integrated treatment concept for Northern corn leaf blight (Setosphaeria turcica) and Kabatiella eyespot (Kabatiella zeae) in maize (Zea mays subsp. mays L.) under Central European conditions. For this purpose, field inoculation trials were carried out for each pathogen over a period of three years at two locations in Germany. Kabatiella eyespot was investigated on two silage maize varieties (Niklas and Ronaldinio). Northern corn leaf blight was investigated on one silage maize variety (SY Amboss) and one grain maize variety (NK Falkone). To inoculate the maize plants, they were sprayed with spore suspensions of the respective pathogen (mixture of representative isolates for Central Europe; S. turcica races 0 and 1). Different inoculation times (BBCH 31 and BBCH 61) and inoculum concentrations (low and high number of spores) were used to generate different levels of disease severity over time. On this basis, disease-yield-loss-relationships could be determined for the two diseases at different stages of maize plant development (BBCH 65-BBCH 83). For grain maize, the grain yield [in t/ha at 14% standard moisture] was chosen as the endogenous variable. For silage maize, the energy yield per unit area (FEE) was chosen [in GJ NEL/ha] (product of the fac-tors biomass yield [t/ha] and energy content [MJ NEL/ha]). Using a regression analysis, a negative significant linear relationship between the respecti-ve endogenous variable and the respective yield parameter for the diseases was establis-hed. The established correlation was successfully subjected to a causality test. For Kabatiella eyespot, a significant correlation between the FEE and the average disease severity (leaf stages L-2-L+2) could be determined only for the Niklas variety. In 2017, the fruit development phase (BBCH macro stage 7) showed the strongest correlation between FEE and disease severity (R² of 0.60 at BBCH 73, R² of 0.62 at BBCH 79). The correlation between FEE and disease severity at flowering was lower (R² = 0.51). Based on the previ-ous findings from the literature and the fact that the fungicides available at the time of the trial were only approved up to BBCH 69, macro stage 6 was selected for all observations. On the basis of six determined disease-yield-loss-relationships and assuming different costs and yield results, a total of 24 economic damage thresholds could be calculated. The FEE of the Ronaldinio variety was not significantly affected by the occurrence of the dise-ase, which is why it was classified as not worthy of control in all cases considered. In the Niklas variety, economic damage thresholds of between 5 and 22% were observed. In addi-tion to the observed quantitative reduction, the occurrence of Kabatiella eyespot also had a significant negative impact on the quality parameters of the harvested crop. As a result, the energy content was reduced. The importance of the variety for the integrated control of this disease was underlined by a variety trial that showed clear differences between the five varieties tested. For Northern corn leaf blight, it was determined that for both silage and grain maize the mean infestation intensity (leaf stages L-2 -L+2) during fruit formation (BBCH macro stage 7) was most strongly correlated with the respective yield parameter (R² = 0.70 silage maize, R² = 0.50 grain maize). Equivalent to Kabatiella eyespot, the economic damage thresholds were determined at macro stage 6 (flowering). For silage maize (SY Amboss variety), a total of eight economic damage thresholds were calculated on the basis of two disease-yield-loss-relationships. Depending on the scenario, these were between 3 and 9% disease severity at flowering. The energy content of the harvested crop was not significantly re-duced by the occurrence of the disease. For the grain maize variety NK Falkone, twelve economic damage thresholds could be determined on the basis of two disease-yield-loss-relationships, which were between 1 and 2% disease severity at flowering. In a variety trial, all five tested varieties showed an influence on the disease severity of Northern corn leaf blight. Moldboard plowing reduced the incidence of Kabatiella eyespot by 73% and Northern corn leaf blight by 47%. Based on infested crop residues, the inoculum survival ability of the two pathogens was investigated over time. No infectious samples could be identified for Kaba-tiella eyespot after twelve months and for Northern corn leaf blight after 24 months. Crop rotation is therefore an effective means of reducing the probability of infestation. In sum, it can be stated that suitable agronomic measures are available for the integrated treatment of the two most important leaf diseases in maize under Central European conditi-ons. These are not only aiming at the prevention of the two pathogens K. zeae and S. turcica, but also provinge to be phytosanitary beneficial for the entire maize cultivation system. In view of the current high level of maize cultivation and the predicted expansion of grain maize cultivation, it is recommended that all available measures shall be used. Fungicide application should only be the last resort.
Keywords: Kabatiella zeae; Setosphaeria turcica; Maize leaf diseases; Maize
German
Ziel der vorliegenden Arbeit war die Entwicklung eines integrierten Behandlungskonzeptes für die Kabatiella-Augenfleckenkrankheit (Kabatiella zeae) und die Turcicum-Blattdürre (Setosphaeria turcica) im Mais (Zea mays subsp. mays L.) unter mitteleuropäischen Ver-hältnissen. Zu diesem Zweck wurden für jeden Erreger Feldinokulationsversuche über einen Zeitraum von drei Jahren an zwei Standorten in Deutschland durchgeführt. Die Kabatiella-Augenfleckenkrankheit wurde auf zwei Silomaisssorten (Niklas und Ronaldinio) untersucht. Die Turcicum-Blattdürre wurde auf einer Silomaissorte (SY Amboss) und einer Körner-maissorte (NK Falkone) untersucht. Zur Inokulation der Maispflanzen wurden diese mit Sporensuspensionen des jeweiligen Erregers besprüht (Gemisch aus repräsentativen Iso-laten für Mitteleuropa; S. turcica Rassen 0 und 1). Durch verschiedene Inokulationszeit-punkte (BBCH 31 und BBCH 61) sowie Inokulumkonzentrationen (niedrige und hohe An-zahl Sporen) konnten unterschiedliche Befallsstärken im zeitlichen Verlauf generiert wer-den. Auf dieser Grundlage konnten Befalls-Verlust-Relationen für die beiden Krankheiten zu unterschiedlichen Entwicklungsstadien der Maispflanze ermittelt werden (BBCH 65–BBCH 83). Für Körnermais wurde dabei der Kornertrag [in t/ha bei 14 % Standardfeuchte] als endogene Variable betrachtet. Für Silomais wurde der Flächenenergieertrag (FEE) ge-wählt [in GJ NEL/ha] (Produkt der Faktoren Biomasseertrag [t TM/ha] und dem Energie-gehalt [MJ NEL/kg TM]). Mittels einer Regressionsanalyse konnte ein negativ signifikant linearer Zusammenhang zwischen der jeweiligen endogenen Variable und dem jeweiligen Ertragsparameter für bei-de Krankheiten festgestellt werden. Der festgestellte Zusammenhang wurde erfolgreich einer Kausalitätsprüfung unterzogen. Für die Kabatiella-Augenfleckenkrankheit konnte nur bei der Sorte Niklas ein signifikanter Zusammenhang zwischen dem FEE und der mittleren Befallsstärke (Blattetagen L-2–L+2) ermittelt werden. Im Jahr 2017 wies die Phase der Fruchtentwicklung (BBCH-Makrostadium 7) den stärksten Zusammenhang zwischen dem FEE und der Befallsstärke auf (R² von 0,60 zu BBCH 73, R² von 0,62 zu BBCH 79). Der Zusammenhang zwischen dem FEE und der Befallsstärke zur Blüte fiel geringer aus (R² = 0,51). Basierend auf den bisherigen Erkenntnissen aus der Literatur und der Tatsache, dass die zum Versuchszeit-punkt zugelassenen Fungizide nur bis BBCH 69 zugelassen waren, wurde für alle Betrach-tungen das Makrostadium 6 gewählt. Auf der Basis von sechs ermittelten Befalls-Verlust-Relationen und unter Annahme unterschiedlicher Kosten und Ertragsergebnisse konnten insgesamt 24 ökonomische Schadschwellen berechnet werden. Der FEE der Sorte Ronal-dinio wurde durch das Auftreten der Krankheit nicht signifikant beeinflusst, weshalb sie in allen betrachteten Fällen als nicht bekämpfungswürdig klassifiziert wurde. Bei der Sorte Niklas konnten ökonomische Schadschwellen zwischen 5 und 22% festgestellt werden. Neben der festgestellten, quantitativen Reduktion reduzierte das Auftreten der Kabatiella-Augenfleckenkrankheit auch die Qualitätsparameter des Erntegutes signifikant. Infolgedes-sen war der Energiegehalt reduziert. Die Bedeutung der Sorte für die integrierte Bekämp-fung dieser Krankheit konnte durch einen Sortenversuch unterstrichen werden, der deutli-che Unterschiede zwischen den fünf getesteten Sorten aufzeigte. Für die Turcicum-Blattdürre konnte sowohl für Silo- als auch für Körnermais eruiert werden, dass die mittlere Befallsstärke (Blattetagen L-2 –L+2) während der Fruchtbildung (BBCH-Makrostadium 7) am stärksten mit dem jeweiligen Ertragsparameter korrelierte (R² = 0,70 für Silomais, R² = 0,50 für Körnermais). Äquivalent zur Kabatiella-Augenfleckenkrankheit erfolgte die Ermittlung der ökonomischen Schadschwellen zum Makrostadium 6 (Blüte). Für die Silomaissorte SY Amboss konnten auf Basis von zwei Befalls-Verlust-Relationen ins-gesamt acht ökonomische Schadschwellen berechnet werden. Diese lagen – je nach Sze-nario – zwischen 3 und 9 % Befallsstärke zur Blüte. Der Energiegehalt des Erntegutes wurde durch das Auftreten der Krankheit nicht signifikant reduziert. Für die Körnermaissorte NK Falkone konnten auf der Basis von zwei Befalls-Verlust-Relationen zwölf ökonomische Schadschwellen ermittelt werden, die zwischen 1 und 2 % Befallsstärke zur Blüte lagen. In einem Sortenversuch zeigten alle fünf getesteten Sorten einen Einfluss auf die Befallsstär-ke der Turcicum-Blattdürre. Durch eine wendende Bodenbearbeitung (Pflug) konnte die Befallshäufigkeit der Kaba-tiella-Augenfleckenkrankheit um 73 % und die der Turcicum-Blattdürre um 47 % reduziert werden. Ausgehend von befallenen Ernterückständen wurde das Inokulumüberdauerungs-vermögen beider Erreger im Zeitverlauf untersucht. Dabei konnten für die Kabatiella-Augenfleckenkrankheit nach zwölf Monaten und für die Turcicum-Blattdürre nach 24 Mona-ten keine infektiösen Proben mehr identifiziert werden. Somit stellt die Fruchtfolge ein pro-bates Mittel zur Reduzierung der Befallswahrscheinlichkeit dar. Zusammenfassend lässt sich konstatieren, dass für eine integrierte Behandlung der beiden wichtigsten Blattkrankheiten im Mais unter mitteleuropäischen Verhältnissen geeignete ackerbauliche Maßnahmen zur Verfügung stehen. Diese zielen nicht nur auf die Prävention der beiden Erreger K. zeae und S. turcica ab, sondern erweisen sich als phytosanitär vor-teilhaft für das gesamte Anbausystem Mais. Angesichts des derzeit hohen Anbauumfangs von Mais und der prognostizierten Ausweitung des Körnermaisanbaus wird empfohlen, alle zur Verfügung stehenden Maßnahmen zu nutzen. Die Fungizidapplikation sollte hierbei das letzte Mittel der Wahl sein.Other Languages
The aim of this study was to develop an integrated treatment concept for Northern corn leaf blight (Setosphaeria turcica) and Kabatiella eyespot (Kabatiella zeae) in maize (Zea mays subsp. mays L.) under Central European conditions.
For this purpose, field inoculation trials were carried out for each pathogen over a period of three years at two locations in Germany. Kabatiella eyespot was investigated on two silage maize varieties (Niklas and Ronaldinio). Northern corn leaf blight was investigated on one silage maize variety (SY Amboss) and one grain maize variety (NK Falkone). To inoculate the maize plants, they were sprayed with spore suspensions of the respective pathogen (mixture of representative isolates for Central Europe; S. turcica races 0 and 1). Different inoculation times (BBCH 31 and BBCH 61) and inoculum concentrations (low and high number of spores) were used to generate different levels of disease severity over time. On this basis, disease-yield-loss-relationships could be determined for the two diseases at dif-ferent stages of maize plant development (BBCH 65-BBCH 83). For grain maize, the grain yield [in t/ha at 14% standard moisture] was chosen as the endogenous variable. For silage maize, the energy yield per unit area (FEE) was chosen [in GJ NEL/ha] (product of the fac-tors biomass yield [t/ha] and energy content [MJ NEL/ha]).
Using a regression analysis, a negative significant linear relationship between the respecti-ve endogenous variable and the respective yield parameter for the diseases was establis-hed. The established correlation was successfully subjected to a causality test.
For Kabatiella eyespot, a significant correlation between the FEE and the average disease severity (leaf stages L-2-L+2) could be determined only for the Niklas variety. In 2017, the fruit development phase (BBCH macro stage 7) showed the strongest correlation between FEE and disease severity (R² of 0.60 at BBCH 73, R² of 0.62 at BBCH 79). The correlation between FEE and disease severity at flowering was lower (R² = 0.51). Based on the previ-ous findings from the literature and the fact that the fungicides available at the time of the trial were only approved up to BBCH 69, macro stage 6 was selected for all observations. On the basis of six determined disease-yield-loss-relationships and assuming different costs and yield results, a total of 24 economic damage thresholds could be calculated. The FEE of the Ronaldinio variety was not significantly affected by the occurrence of the dise-ase, which is why it was classified as not worthy of control in all cases considered. In the Niklas variety, economic damage thresholds of between 5 and 22% were observed. In addi-tion to the observed quantitative reduction, the occurrence of Kabatiella eyespot also had a significant negative impact on the quality parameters of the harvested crop. As a result, the energy content was reduced. The importance of the variety for the integrated control of this disease was underlined by a variety trial that showed clear differences between the five varieties tested.
For Northern corn leaf blight, it was determined that for both silage and grain maize the mean infestation intensity (leaf stages L-2 -L+2) during fruit formation (BBCH macro stage 7) was most strongly correlated with the respective yield parameter (R² = 0.70 silage maize, R² = 0.50 grain maize). Equivalent to Kabatiella eyespot, the economic damage thresholds were determined at macro stage 6 (flowering). For silage maize (SY Amboss variety), a total of eight economic damage thresholds were calculated on the basis of two disease-yield-loss-relationships. Depending on the scenario, these were between 3 and 9% disease severity at flowering. The energy content of the harvested crop was not significantly re-duced by the occurrence of the disease. For the grain maize variety NK Falkone, twelve economic damage thresholds could be determined on the basis of two disease-yield-loss-relationships, which were between 1 and 2% disease severity at flowering. In a variety trial, all five tested varieties showed an influence on the disease severity of Northern corn leaf blight.
Moldboard plowing reduced the incidence of Kabatiella eyespot by 73% and Northern corn leaf blight by 47%. Based on infested crop residues, the inoculum survival ability of the two pathogens was investigated over time. No infectious samples could be identified for Kaba-tiella eyespot after twelve months and for Northern corn leaf blight after 24 months. Crop rotation is therefore an effective means of reducing the probability of infestation.
In sum, it can be stated that suitable agronomic measures are available for the integrated treatment of the two most important leaf diseases in maize under Central European conditi-ons. These are not only aiming at the prevention of the two pathogens K. zeae and S. turcica, but also provinge to be phytosanitary beneficial for the entire maize cultivation system. In view of the current high level of maize cultivation and the predicted expansion of grain maize cultivation, it is recommended that all available measures shall be used. Fungi-cide application should only be the last resort.
Schlagwörter: Blattkrankheiten Mais; Mais; Setosphaeria turcica; Kabatiella zeae