A Systematic Review and Quantitative Synthesis of the Efficacy of Quaternary Ammonium Compounds in Disinfesting Nonfungal Plant Pathogens

Authors: Copes, Warren; OJIAMBO, PETER - North Carolina State University

Submitted to: Plant Disease
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 3/4/2023
Publication Date: 10/23/2023
Citation: Copes, W.E., Ojiambo, P.S. 2023. A Systematic Review and Quantitative Synthesis of the Efficacy of Quaternary Ammonium Compounds in Disinfesting Nonfungal Plant Pathogens. Plant Disease. 105:4084-4094. https://doi.org/10.1094/PDIS-12-21-2751-RE.
DOI: https://doi.org/10.1094/PDIS-12-21-2751-RE

Interpretive Summary: uaternary ammonium compounds (QACs) have been used as disinfestants to inactivate plant pathogens since the mid-twentieth century. Many studies have shown QAC disinfestants to be highly effective, while others have shown moderate to poor activity against some plant pathogens and when treating some production surfaces. Commercial labels of QAC disinfestants adjust rates and contact times depending on the application or surface being treated, but the adjustments may not be comprehensive enough. A systematic literature review was done to obtain an overview of control responses and variances resulting from QAC disinfestant applications to inactivate bacteria, fungi, oomycetes and viruses in multiple production applications. A meta-analysis was performed on data involving plant pathogen and disease control in production of agricultural and horticultural plant hosts, including three subgroup analyses on twelve dose and contact time categories, on four taxonomic organism categories, and on seven substrate categories. Significant differences were found with the more meaningful differences due to substrates. However, the biggest issue was the range in magnitude of effect size means, which is a reflection of the inconsistency in control activity. Discussion addresses the impact of organism sensitivity to QAC-disinfestants, QAC-disinfestant reactivity to substrates and the selection of QAC compounds on achieving control activity. This information provides practical considerations for selecting disinfestant products to be used agricultural and horticultural production systems, but also highlights the shortage in available research information.

Technical Abstract: Quaternary ammonium compounds (QACs) have been used as disinfestants to inactivate plant pathogens on tools, equipment, production surfaces and harvested produce surfaces in plant production systems since the mid-twentieth century. A systematic review was performed to evaluate overall efficacy of QACs, which included products with some mixture of nine active ingredients, to inactivate plant pathogens specifically. In many studies, QAC disinfestants have been highly effective, while in other studies biocidal activity was poor against some plant pathogens; this has resulted irrespective of rates from 0.05 to 10% product and exposure times from 2 sec to 60 min. A meta-analysis comparing a control and QAC-disinfestant intervention treatment was performed on 129 cases that involved diverse plant pathogens from many agricultural and horticultural crop production systems. Three subgroup analyses were performed: one on ten dose and contact time combination categories, one on four taxonomic organism categories, and one on nine substrate categories. Significant differences were found between in all three subgroup analyses, some differences being more meaningful than others. The most consistent findings were the overall precision was low and the heterogeneity and dispersion was high for the summary effects in all four subgroup analyses. Factors that could influence heterogeneity are discussed and evaluated from the existing literature, including diversity of organisms tested, differences in organism sensitivity to QAC-disinfestants, efficacy differences of QAC active ingredients, and QAC-disinfestant reactivity to substrates.