Occurrence of the late leaf spot complex of barley and its consequences on optimized disease control

The leaf spot complex constitutes an increasing challenge for integrated pest control in barley. The complex consists of biotic and abiotic factors causing early ripening after a rapid loss of green leaf area, in particular in upper, exposed leaves. Severe symptoms appear late in the growing season...

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Bibliographic Details
Published in:Gesunde Pflanzen 2007-06, Vol.59 (2), p.47-54
Main Authors: Hess, Michael, Habeker, Roland, Kick, Matthias, Hausladen, Matthias Martin und Hans
Format: Article
Language:English
Subjects:
Hordeum vulgare
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Summary:The leaf spot complex constitutes an increasing challenge for integrated pest control in barley. The complex consists of biotic and abiotic factors causing early ripening after a rapid loss of green leaf area, in particular in upper, exposed leaves. Severe symptoms appear late in the growing season after heading. The experience from recent years shows that the control of the leaf spot complex improves yield. Best control is achieved by new, effective fungicides. Efficiency is improved by late fungicide application and is dose- dependent. In contrast, late treatments provide poor control of early appearing diseases. For a successful disease control in barley good efficiency in the control of the leaf spot complex appears based on a sufficient control of the other diseases. For optimization of disease control, we require improved knowledge of the epidemics of the leaf spot complex and of the contribution of individual biotic and abiotic factors. Besides the weather, the fungal pathogen Ramularia collo-cygni and its photodynamic toxins play a mayor role in symptom development. By combination of conventional and molecular diagnostics we aim at a better understanding of the complex as a basis for early and reliable prediction of epidemics. Because non fungicidal factors like the physiological plant age play a significant role in the occurrence of the leaf spot complex, they should be taken into account for integrated control.Original Abstract: Die zunehmende Bedeutung des Blattfleckenkomplexes in der Gerste stellt eine wachsende Herausforderung fuer den integrierten Pflanzenschutz dar. Beim Blattfleckenkomplex kommt es aufgrund von biotischen und abiotischen Einflussfaktoren zu einer schnell fortschreitenden Nekrotisierung besonders der oberen, exponierten Blattetagen und einer fruehzeitigen Abreife. Bisherige Ergebnisse belegen, dass die Kontrolle des nach dem Aehrenschieben auftretenden Blattfleckenkomplexes ertragsrelevant ist. Die beste Kontrolle wird durch den Einsatz neuer, wirksamer Fungizide zu spaeten Einsatzterminen in Abhaengigkeit von der Aufwandmenge erreicht. Dabei werden frueh auftretende Pathogene in der Regel nicht mehr erfasst. Bei einer Bekaempfungsstrategie baut die gute Wirkung gegenueber dem Blattfleckenkomplex auf einer ausreichenden Pathogenkontrolle auf. Die Optimierung der Massnahmen fuer eine gezielte und wirtschaftliche Bekaempfung setzt eine bessere Kenntnis der Epidemiologie des Blattfleckenkomplexes und der biotischen und abiotisc
ISSN:0367-4223
1439-0345
DOI:10.1007/s10343-007-0140-8