Chemical and biological control of Sclerotinia sclerotiorum in witloof chicory culture.

Abstract

Sclerotinia sclerotiorum (Lib.) de Bary is a major pathogen of witloof chicory. For lack of authorised field treatment, post-harvest sprays with dicarboximide fungicides have been standard practice since the 1970s to prevent root rot and chicory heart decay during the forcing phase. However, the registration of procymidone and vinclozolin has been withdrawn in Europe. The development of organic agriculture and the necessity to reduce fungicide applications in conventional agriculture prompted an assessment of the efficacy of new fungicides and the use of the mycoparasite Coniothyrium minitans (Campbell). A mixture of the fungicides fludioxonil and cyprodinil (Switch(®) ) applied on chicory roots achieved a very good control of S. sclerotiorum (up to 95%). The use of C. minitans limited root infection, both when applied in the field (50-65% efficacy) and before the forcing period (post-harvest treatment up to 80%). In organic agriculture, two treatments with C. minitans (in field and later at the forcing period) could improve protection against S. sclerotiorum. In conventional agriculture, after the field biological treatment, a post-harvest chemical treatment could be applied. The addition of other prophylactic methods could lead to a high level of performance in practice against decay caused by S. sclerotiorum.