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Influence of pruning systems on trunk pathogens and other fungi colonizing grapevine wood
R. TRAVADON (1), P. Lecomte (2), B. Diarra (2), D. P. Lawrence (1), J. Vallance (2), H. Ojeda (3), P. Rey (2), K. Baumgartner (4). (1) Univ of California, Davis, CA, U.S.A.; (2) INRA, UMR 1065 SAVE, Université de Bordeaux, ISVV, Villenave d'Ornon, France; (3) INRA, Unité Expérimentale de Pech Rouge, Gruissan, France; (4) USDA-Agricultural Research Service, Davis, CA, U.S.A.

The main infection courts for fungal grapevine trunk pathogens are pruning wounds. Disease control practices typically involve modifications to pruning. Pruning practices requiring fewer/smaller wounds may thus be associated with fewer trunk pathogens and less wood necroses. We examined wood-colonizing fungi in the trunks of 14-year-old vines (<i>Vitis vinifera</i> ‘Mourvèdre’ at site A, ‘Syrah’ at site B), either spur-pruned or minimally (min-) pruned. At each site, the trunks of eight min-pruned and eight spur-pruned vines were characterized in terms of proportions of necrotic wood and the community structure of the 88 cultivable fungal taxa identified through ITS sequencing. Spur-pruned vines had more wood necroses (35% vs. 20% in min-pruned vines) and a greater diversity of taxa, but not a greater abundance of trunk pathogens. Instead, Canonical Correspondence Analysis revealed different trunk pathogens: <i>Diaporthe ampelina</i> and <i>Togninia minima</i> were associated with spur pruning, and <i>D. foeniculina</i>, <i>Neofusicoccum parvum</i>, and <i>Phaeomoniella chlamydospora</i> with min-pruning. Among the 15 most abundant taxa, eight were more common in spur-pruned vines (e.g., wood endophytes <i>Aureobasidium pullulans, Bionectria ochroleuca</i>), compared to only five in min-pruned vines (e.g., <i>Paraconiothyrium brasiliense, Pestalotiopsis microspora</i>). Spur-pruned vines were associated with more plant pathogenic taxa, which may contribute to greater levels of wood necrosis.

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