Evaluation of non-chemical seed treatment methods for the control of Phoma valerianellae on lamb's lettuce seeds / Evaluierung nichtchemischer Saatgutbehandlungsverfahren zur Bekämpfung von Phoma valerianellae an Feldsalatsamen

• Published in: Journal of plant diseases and protection (2006) 2009-10, Vol.116 (5), p.200-207
• Main Authors: Schmitt, A., Koch, E., Stephan, D., Kromphardt, C., Jahn, M., Krauthausen, H.-J., Forsberg, G., Werner, S., Amein, T., Wright, S.A.I., Tinivella, F., van der Wolf, J., Groot, S.P.C.
• Format: Article
• Language: English
• Subjects: Field experiments; Hot water treatment; Infections; Pathogens; Plants; Seed treatment; Seedlings; Seeds; Steam; Thyme
• ISSN: 1861-3829; 1861-3837

The aim of the present study was to identify seed treatment methods for eradicating Phoma valerìanellae from lamb's lettuce seeds in organic vegetable production. Using seeds naturally infested with the pathogen, the effect of three physical methods (hot water, aerated steam, electron treatment) and different agents of natural origin (micro-organisms, plant derived products, resistance inducers) was tested on moist filter paper, in seed trays under controlled conditions and in the field. In an initial screening, none of the tested putative resistance inducers prevented infection by P. valerianellae , while two out of seven formulated micro-organism preparations and six out of 16 experimental microbial strains were effective. When selected agents and the three physical seed treatment methods were compared in blotter and seed tray tests, the physical methods were generally the most effective treatments, while the micro-organism treatments were clearly less efficacious. However, in field experiments with the same seed lots and the same treatments, a statistically significant increase in plant stand was not obtained with any of the treatments. Combinations of the three physical treatment methods with selected non-chemical agents did not perform better than the physical treatments alone. The most effective alternative seed treatments identified in the present study, aerated steam, hot water, electron treatment and thyme oil (0.1%), can be recommended for eradication of P. valerianellae from lamb's lettuce seeds in organic farming. Because their efficacy was generally as high as that of the chemical fungicide Aatiram (active ingredient thiram), they are also potentially suited for use in conventional vegetable production. Ziel der vorliegenden Untersuchung war es, für den ökologischen Landbau geeignete Saatgutbehandlungsverfahren zur Bekämpfung von Phoma valerianellae an Feldsalat zu finden. Dazu wurde die Wirksamkeit von drei physikalischen Verfahren (Heißwasserbehandlung, Heißluftbehandlung, Elektronenbehandlung) und verschiedenen Agenzien natürlicher Herkunft (Mikroorganismen, pflanzliche Präparate, Resistenzinduktoren) mit natürlich infiziertem Saatgut auf Filterpapier, unter kontrollierten Bedingungen in Saatschalentesten sowie in Feldversuchen untersucht. In der ersten Überprüfung konnte keines der Mittel, bei denen eine Resistenzinduktion als Wirkmechanismus angenommen wurde, die Infektion mit P. valerianellae verhindern, während zwei von sieben formulier