Abstract

Diplodia seriata and D. mutila are among the fungal species causing Botryosphaeria dieback “dead arm” disease in vineyards in Chile. Many grapevine crops are cultivated on their own roots, although some are grafted on rootstocks. It seemed important to analyze the susceptibility of different vine cultivars currently in use, to infection by these fungi. Oneyear-old canes of wine grape cvs. Cabernet Franc, Malbec, Merlot, Sauvignon Blanc and Syrah (all on their own roots), and of table grapes cvs. Thompson Seedless, Flame Seedless, Crimson Seedless, and Red Globe (all rootstock Harmony), were evaluated. Ten cane sections per cv. were inoculated with D. seriata and D. mutila (wine grape) or with D. mutila (table grape) and incubated in the dark at 25ºC and 95% humidity. The length of necrotic lesions observed at the internode region, was measured from both sides of the inoculation point with a vernier, after careful removal of the bark. Results showed that the mean length of lesions caused by D. mutila (2.9±0.1 cm) were three times greater than those produced by D. seriata in grapevine canes. Cvs. Cabernet Franc and Syrah were the most susceptible to D. mutila and Merlot was the least susceptible. No significant differences were observed between grapevine cvs. inoculated with D. seriata, or between table grape cvs. inoculated with D. mutila. Field experiments (four plants with five repeats for each cultivar) on Cabernet Sauvignon and on Chardonnay on their own roots, inoculated with D. seriata, showed that lesions in the Cabernet Sauvignon cv. were larger than those produced in the Chardonnay cv. These last results agree with those obtained in grapevine seedlings, where the cv. Chardonnay had greater activity of several pathogenesis related proteins than cv. Cabernet Sauvignon.