Early detection project – make a GTD infection visible without disease symptoms

Abstract

Context and purpose of the study ‐ The presence of grapevine trunk diseases (GTDs) related pathogens leads to severe economic losses in wine‐growing regions all over the world. GTDs cause foliar discoloration, stunted growth, decline, sectorial and/or central necrosis of the trunk wood, and dieback, while the quality and the quantity of the grapes and therefore the wine production is reduced. The disease management is challenging for vine‐growers since the responsible fungi colonize wood tissues (and are therefore inaccessible for conventional fungicides) and the related symptoms occur mostly after a long period of latency. The aims of this project were first to distinguish between healthy and infected plants before the symptoms appear and second to document the efficacy of BASF ´s Tessior®‐ System for wound protection under field conditions.

Material and methods ‐ Long term field trials were established between 2014 and 2015 in Germany, France, Greece, and Italy, where each year the pruning wounds are treated with Tessior®. In order to increase the infection pressure, some of the vineyards are artificially inoculated with spores of Phaeomoniellachlamydospora and Botryosphaeriaceae species. The presence of P. chlamydospora – a pathogen causing esca‐disease – and Botryosphaeriaceae species – causing Botryosphaeria dieback – in grapevines was determined with an optimized protocol. Samples were collected by drilling a 5 mm diameter hole in the spurs below a pruning wound which was closed then with a wound sealant. The wood chips were lyophilized and afterwards homogenized using TissueLyser II (Qiagen). Total genomic DNA was extracted from the grapevine samples and quantitative Real‐Time PCR using TaqMan probes was performed.

Results ‐ This protocol has been proved to be fast and accurate to quantify the DNA amount of GTDs related pathogens in grapevine wood. Furthermore, the efficacy of Tessior® wound protectant has been verified showing significant reduction of infection with P. chlamydospora and Botryosphaeriaceae species.