Dissemination of Botryosphaeriaceae conidia in vineyards in the semiarid Mediterranean climate of the Valparaíso Region of Chile

Abstract

The dispersal of Botryosphaeriaceae conidia was studied in two vineyards in the Valparaiso Region of Chile, where semiarid Mediterranean climate conditions prevail. The objective of this study was to record trappings of Botryosphaeriaceae conidia over one year on a weekly basis and to associate these records with weather and agrochemical application data. Two Chardonnay vineyards in Casablanca and two Cabernet Sauvignon vineyards in Panquehue were selected. In each vineyard at each weekly sampling, five microscope slides covered with petroleum jelly (Vaseline) were installed near grapevines affected by Botryosphaeria cankers. In addition, Botryosphaeriaceae species associated with cankers in these vineyards were identified. Seasonal peaks of Botryosphaeriaceae conidia were detected among the different grape producing areas. In Casablanca, peaks of conidium dispersal were observed in winter 2013 and in autumn and winter 2014. Peaks of large numbers of conidia were mainly associated with precipitation events equal to or greater than 0.2 mm. The species observed in the spore traps were preliminarily identified as Diplodia seriata, Spencermartinsia viticola and Neofusicoccum sp., and isolations from adjacent plants confirmed the presence of D. seriata, S. viticola and N. australe in these vineyards. In Panquehue, peaks of conidium dispersal were observed in winter 2013, with a lower relative abundance of spores detected compared with Casablanca. Conidia dispersal recommenced in autumn 2014 but remained low later in winter. In this location, D. seriata was the main species detected, followed by S. viticola. No Neofusicoccum species was detected in this area. No association was found between conidium dispersal and the volume of water (≤ 1000 L ha^-1) used in the application of agrochemical products.