This quantitative review and systematic analysis of the effectiveness of quaternary ammonium compounds (QACs) in disinfesting non-fungal plant pathogens in agricultural and horticultural cropping systems is a complementary follow-up to a previous study that evaluated the efficacy of QACs against fungal plant pathogens. In the present study, a meta-analysis involving 67 studies was conducted to assess the overall efficacy of QACs against plant pathogenic bacteria, oomycetes and viruses, and to identify factors associated with observed differences in product efficacy. Across all studies, QACs resulted in a significant (P < 0.0001) reduction in either disease intensity or propagule viability with a mean Hedges' g (g+) of 1.75, indicating that overall QAC treatments were moderately effective against non-fungal pathogens. Significant differences in product efficacy were observed between organism types (P = 0.0001), with QAC interventions resulting in higher efficacy (P = 0.0002) against oomycetes ( g+ = 4.20) than against viruses ( g+ = 1.42) and bacteria ( g+ = 1.07), which were not different (P = 0.2689) from each other. As a result, bacterium and virus types were combined into a composite set (BacVir). QAC intervention against BacVir resulted in significant differences in efficacy within categorical moderator subgroups for genus (P = 0.0133), target material (P = 0.0001) and QAC product generation (P = 0.0281). QAC intervention against oomycetes resulted in significant differences in efficacy only for genus (P < 0.0001). For the BacVir composite, five random effects (RE) meta-regression models were significant (P = 0.05), where models with dose and time, dose and genus, time and genus, dose and target; and time and target accounted for 62%, 61%, 52%, 83% and 88%, respectively, of the variance in true effect sizes (R2) associated with . For oomycetes, three RE meta-regression models were significant (P = 0.05), where models with dose and time; dose and genus, and time and genus accounted for 64%, 86% and 90 %, respectively, of R2 associated with g+. These results show that while QACs are moderately effective against non-fungal plant pathogens, the observed variability in their efficacy due to dose of active ingredient and contact time of these products can be influenced by organism type, genus within organism type, the target being treated, and the generation of QAC products.