Trichoderma spp. and Bacillus subtilis for control of Dactylonectria macrodidyma in grapevine

Black foot disease, which is primarily caused by Dactylonectria species, affects young and mature grapevines, causing loss of productivity and reduction of longevity of vineyards. Because it is a soil-borne fungus, this pathogen offers limited control possibilities. This study aimed to assess the biocontrol activity of products based on Trichoderma spp. and Bacillus subtilis, in vitro and in vivo, against D. macrodidyma. In vitro assays were carried out to evaluate inhibition of mycelial growth of the pathogen through volatile metabolites and paired cultures assays. An in vivo experiment evaluated the potential biocontrol of the pathogen in plants of Vitis vinifera cv. Merlot, grafted on ‘Paulsen 1103’. In the volatile metabolites assay, mean inhibition of mycelial growth in treatments using Trichoderma spp. was 59%. In the paired cultures experiment, treatment with B. subtilis (Rizolyptus®) gave 41% inhibition of the pathogen. In the in vivo assay, the best results for length of the primary shoots, total numbers of nodes and root dry weight were achieved with the B. subtilis treatments. This study demonstrates that B. subtilis has potential for biocontrol of D. macrodidyma