LAUSR

A meta-analysis was performed using 124 studies to evaluate the disinfestation efficacy of quaternary ammonium compounds (QAC) to reduce either disease intensity or propagule viability of fungal plant pathogens in crop production systems. The population mean effect size was 2.16, using a Hedges' g standardized mean difference, and indicated that QACs on average were highly effective. However, heterogeneity was significant (P < 0.0001) with 78.5% of the observed variance consisting of variance in true effects and a high estimate of between-study variability (τ2 = 2.15). Two continuous (dose and time) and three categorical (pathogen genus, target material and QAC product generation) moderator variables were used to evaluate heterogeneity. Meta-regression models with two continuous moderators or one continuous and one categorical moderator were used to evaluate QAC efficacy. Dose and time accounted for only 8% and 4%, respectively, of the true variance in effect sizes (P = 0.0004). For meta-regression models with dose or time, genus accounted for 40% (P = 0.0008) and 51% (P = 0.0007), respectively; target material accounted for 18% (P = 0.0001) and 19% (P = 0.0001), respectively; and QAC product generation accounted for 24% (P = 0.0034) and 21% (P = 0.0189), respectively, of the true variance in effect sizes in individual models. The results show that the current recommended rates of QAC products are generally effective, but efficacy is likely to be influenced by the fungal genus and target being treated and the generation of the QAC product used for disinfestation.