Mycobiota associated with “Grapevine Trunk Disease” in San Juan, Argentina

In recent decades, in San Juan, Argentina, grapevine trunk disease has become one of the most damaging phytosanitary problems affecting crops. In this country, this disease is commonly known as “Malvón leaf,” and has only been studied in vineyards in the province of Mendoza. In this comprehensive study, the mycobiota associated with grapevine crops destined for fresh grapes of the Superior seedless and Cardinal varieties was meticulously analyzed. Morphological studies and molecular analyses confirmed the presence of several fungal species, including Arambaria cognata, Acremonium sp., Alternaria alternata, Alternaria sp., Eutypella microtheca, Lasiodiplodia crassispora, Lasiodiplodia theobromae, Phaeoacremonium parasiticum, and Phoma sp. Pathogenicity tests conducted on one-year-old plant trunks for E. microtheca, L. theobromae, and L. crassispora complied with Koch’s postulates. This is the first record of these three species in Argentine vineyards and highlights the urgent need to consider them as a significant threat to the region’s viticultural heritage and sustainability.