Newly-assessed fungicides for the control of cypress canker caused by Seiridium cardinale

Abstract

Bark canker caused by Seiridium cardinale is the most destructive disease of Cupressus and several Cupressaceae in many temperate regions and particularly in the Mediterranean area. Chemical prevention represents the most effective and essential means of control to protect plant production in nurseries and young plantations. The European Directive 2009/128/CE and CE 1107/2009 application have drastically reduced the number of chemicals that can be used in agriculture, including the benzimidazolic compounds that had shown the best results in preventing S. cardinale canker. It is therefore urgent to find alternative fungicides to replace the banned compounds. The purpose of the present work was to assess some fungicides through in vitro tests and pre- and post-inoculation sprayings on Cupressus sempervirens, for the control of S. cardinale. The active ingredients boscalid, fosetyl-aluminium, triadimenol and azoxystrobin were compared with thiophanate-methyl as reference. The effectiveness of thiophanate-methyl in reducing canker development was confirmed especially when it was applied to trees before they were inoculated with S. cardinale. Azoxystrobin was as effective as thiophanate-methyl in the pre-inoculation trials. boscalid prevented conidial germination and mycelial growth of S. cardinale in vitro and appeared a promising contact fungicide for the prevention of cypress canker. Azoxystrobin and boscalid are listed in a less hazardous class than thiophanate-methyl, and has less risk for the environment and for users.