Biological control of Botryosphaeria dieback of grapevines.
Citation
Úrbez-Torres, J.R., Pollard-Flamand, J., Boulé, J., and Hart M. Biological control of Botryosphaeria dieback of grapevines. Phytopathologia Mediterranea 61:344-345.
Résumé en langage clair
Botryosphaeria dieback (BD) is a grapevine trunk disease (GTD) that causes important grape yield losses
and limits vineyard lifespans. Botryosphaeriaceae spp. causing BD infect grapevines through pruning wounds.
Therefore, pruning wound protection is the most effective and available management strategy for this disease.
Demand has increased for alternatives to chemical products and sustainable control methods to manage
GTDs. With no control products currently registered in Canada against GTDs, the present research aimed
to identify local Trichoderma biological control agents (BCAs), and evaluate their potential against the BD
pathogens Diplodia seriata and Neofusicoccum parvum. A total of 29 Trichoderma isolates were obtained from
vineyards in British Columbia. Morphological studies and phylogenetic analyses of the ITS1-5.8S-ITS2 gene
and TEF-1α partial gene identified seven species (T. asperelloides, T. atroviride, T. harzianum, T. koningii,
T. tomentosum), and two novel species, T. canadense and T. viticola. In vitro dual culture antagonism assays
showed that several isolates inhibit pathogen mycelium growth, by up to 75%. In planta detached cane assays
under controlled greenhouse conditions identified T. asperelloides, T. atroviride and T. canadense isolates
gave 70% to 100% pruning wound protection against D. seriata and N. parvum for up to 21 d after treatment.
Field trials conducted in ‘Merlot’ vines in 2019 and 2020 showed that mixed-species inoculum of T. asperelloides, T. atroviride and T. canadense had high biocontrol activity against BD fungi for up to 60 d after treatment. Field results also showed that the Trichoderma spp. provided similar or greater pruning wound protection when compared with commercial chemical or biocontrol products. This study provides data supporting development and registration of the first control products against GTDs in Canada.
Résumé
Botryosphaeria dieback (BD) is a grapevine trunk disease (GTD) that causes important grape yield losses
and limits vineyard lifespans. Botryosphaeriaceae spp. causing BD infect grapevines through pruning wounds.
Therefore, pruning wound protection is the most effective and available management strategy for this disease.
Demand has increased for alternatives to chemical products and sustainable control methods to manage
GTDs. With no control products currently registered in Canada against GTDs, the present research aimed
to identify local Trichoderma biological control agents (BCAs), and evaluate their potential against the BD
pathogens Diplodia seriata and Neofusicoccum parvum. A total of 29 Trichoderma isolates were obtained from
vineyards in British Columbia. Morphological studies and phylogenetic analyses of the ITS1-5.8S-ITS2 gene
and TEF-1α partial gene identified seven species (T. asperelloides, T. atroviride, T. harzianum, T. koningii,
T. tomentosum), and two novel species, T. canadense and T. viticola. In vitro dual culture antagonism assays
showed that several isolates inhibit pathogen mycelium growth, by up to 75%. In planta detached cane assays
under controlled greenhouse conditions identified T. asperelloides, T. atroviride and T. canadense isolates
gave 70% to 100% pruning wound protection against D. seriata and N. parvum for up to 21 d after treatment.
Field trials conducted in ‘Merlot’ vines in 2019 and 2020 showed that mixed-species inoculum of T. asperelloides, T. atroviride and T. canadense had high biocontrol activity against BD fungi for up to 60 d after treatment. Field results also showed that the Trichoderma spp. provided similar or greater pruning wound protection when compared with commercial chemical or biocontrol products. This study provides data supporting development and registration of the first control products against GTDs in Canada.