Esca (black measles) and brown wood-streaking : Two old and elusive diseases of grapevines

Research on the etiology of esca, which started at the end of the nineteenth century in France, can be divided into three periods. The first period began in 1898 with Ravaz and ended in 1926 with Viala. The overall conclusion of this period was that two basidiomycetous fungi, Stereum hirsutum (Willd.) Pers. and Phellinus (Fomes) igniarius (L.:Fr.) Quel., were the causal agents, although this could not be shown by pathogenicity tests. However, in Italy in 1912, Petri successfully reproduced some early internal esca symptoms with two undetermined species of Cephalosporium and one of Acremonium that had also been associated with the disease. The second period in esca research started in California in 1957 with Hewitt and lasted until 1959, when Chiarappa detected the relationship between internal wood decay and black measles. He also showed how a Cephalosporium sp. reproduced in vivo some of the symptoms observed in the wood of diseased vines, and how P. igniarius caused wood decay in vitro. The third period, initiated by Larignon and Dubos in 1987 and still underway, is directed at understanding the role of the mitosporic (asexually reproducing) fungi that act alone or together with the basidiomycetes to cause esca and related diseases. This paper refers mostly to conditions in the Mediterranean area and focuses on the progress achieved in our understanding of esca over the last few years. Reference is also made to a decline of young grapevines caused by some of the same mitosporic fungi as those commonly associated with esca in adult vines. Finally, the relations between esca and related syndromes or diseases are also discussed.