Abstract
We analysed symptoms, wood lesions and fungi associated with esca in mature organic vineyards in the Languedoc-Roussillon region. Most previous surveys concerning esca syndrome were conducted in conventionally managed vineyards in other regions. We first found that esca may be present at a very low level in vineyards that were not treated with sodium arsenite. Affected vines displayed three types of symptoms: leaves with interveinal necrosis, wilt of entire branches and these two symptoms in combination. During the 3-year survey, not all affected vines displayed symptoms every year and the same vine rarely displayed the same symptom or combination of symptoms in successive years. The incidence of esca appeared to be correlated with the percentage of vines that died during the survey but no correlation was found with either mortality before the survey or with the age of the vineyard. Observation of cross-sections of a total of 210 vines with esca symptoms and isolation of fungi from the wood lesions led to similar results to those obtained in conventionally managed vineyards. Four different lesions were identified: a white rot lesion, a brown lesion in a central position, a brown lesion in a sectorial position and a scattered black spotting in healthy wood. The most frequently observed fungal species were Fomitiporia mediterranea (Fom), Phaeomoniella chlamydospora, Phaeoacremonium aleophilum and Eutypa lata. The white rot lesion caused by Fom was generally accompanied by one or more other lesions in the same vine. Similarly, Fom was generally isolated with one or several other fungi. No relationship was detected between the expression of external symptoms and any specific lesion or fungus. Our study also showed that esca and Eutypa dieback are often superimposed in our region of sampling