Biological control for grapevine crown gall through soil injection with Allorhizobium vitis strain ARK-1

Grapevine crown gall (GCG), caused by tumor-inducing strains of Allorhizobium vitis (= Rhizobium vitis), is a threat to grapevines around the world. Previously, nonpathogenic A. vitis strain ARK-1 emerged as a promising biological control agent, demonstrating remarkable efficacy in root soaking procedures before planting. This study aims to evaluate the treatment effects when applying soil injection procedures post-planting, both in greenhouse and field experiments. The results of the treatment effects obtained from 21 experiments over 9 years (2009 to 2017) were analyzed and evaluated by a general linear mixed model (GLMM) and a network meta-analysis (NMA). The GLMM results revealed a significant association between the factors "soil injection" and "root soaking" with biological control activity. Subsequently, the NMA results showed that the estimated relative ratio (RR) following root soaking and soil injection treatments with ARK-1 was 0.16 and 0.30, respectively. In summary, while the control efficacy of root soaking with ARK-1 exceeded that of soil injection, the latter method also proved effective in managing GCG. Therefore, soil injection is recommended as a viable approach for GCG control.