Effectiveness of thiophanate-methyl, trifloxystrobin and vinclozolin on canker caused by Phoma exigua Desm. on ash tree seedlings

Abstract

In recent years several cases of cankers caused by Phoma exigua on ash tree seedlings have been reported in Belgian nurseries, leading to a total loss of the affected crops. Similar symptoms have been observed on ash tree seedlings elsewhere in Europe, notably in France and in Great Britain, but the pathogenicity was never established. Inoculation and re-isolation tests were therefore undertaken and demonstrated the phytopathogenic character of P. exigua on ash. Moreover the effectiveness of three fungicides (thiophanate-methyl, trifloxystrobin, vinclozolin) against stem canker of ash tree seedlings was studied. In vitro tests were conducted to evaluate the ability of these fungicides to inhibit mycelium growth and spore germination. The extent to which they reduced the symptoms was estimated in a field trial. The results of this study allowed to get by the Belgian proper authorities the use extension of thiophanate-methyl for the control of canker caused by P. exigua in forest nurseries.

Keywords

• Phoma
• canker
• Fraxinus
• ash tree
• nursery
• fungicides
• thiophanate-methyl
• trifloxystrobin
• vinclozolin
• in vitro
• field trial