From the Lab to the Field: Using Endophytic Bacteria as Biocontrol Agents Against Trunk Diseases in Vineyards.


Bacterial isolates selected from previous AVF grants (2019-2332 and 2021-2573) alongside other beneficial fungal isolates were investigated as potential biocontrol agents against grapevine trunk diseases pathogens. The biocontrol agents were applied as pruning wound protectants (i), as dipping treatments of propagation material prior grafting in nurseries (ii), and as soil drench applications (iii). Results of the second-year experiments are herein presented and discussed. Results showed that as pruning wound protectants, the synthetic fungicides and sealants significantly reduced the infection percentages by Neofusicoccum parvum when compared to the controls and other biocontrol treatments. From nursery trials, the biocontrol treatments with bacterial and fungal products improved the callus formation in graft union and rootstock, respectively. Furthermore, the different fungal-based fungicides (i.e. Vintec, Botector, among others) reduced the recovery of Botryosphaeriaceae and Fusarium pathogens from the graft union. Finally, the results from the soil drench trial showed that treatments with Trichoderma, Rhyme, and Serratia plymuthica reduced the recovery of Neofusicoccum parvum compared to the control, however they did not significantly reduce the lesion length. The treatments with Pseudomonas chlororaphis, and Trichoderma reduced the recovery of Eutypa lata compared to the control, whereas a different treatment based on Trichoderma, alongside Bacillus velezensis and Rhyme significantly reduced the lesion length. The treatments with bacterial endophytes (Bacillus velezensis and Pseudomonas chlororaphis) effectively reduced the recovery of Phaeoacremonium minimum up to 0%, however only the latter significantly reduced the lesion length. Altogether, these results indicate that biocontrol strategies have comparable reductions of the impact of grapevine trunk disease pathogens in field conditions and should be further studied for validation and development for the industry.