Skip to main content
ARS Home » Southeast Area » Poplarville, Mississippi » Southern Horticultural Research Unit » Research » Publications at this Location » Publication #374079
Title: Eliminating the loropetalum knot bacterium from stainless steel, pressure-treated wood and loropetalum stem surfaces

Author
item Copes, Warren

Submitted to: Louisiana Nursery and Landscape Association
Publication Type: Trade Journal
Publication Acceptance Date: 5/28/2020
Publication Date: 6/23/2020
Citation: Copes, W.E. 2020. Eliminating the loropetalum knot bacterium from stainless steel, pressure-treated wood and loropetalum stem surfaces. Louisiana Nursery and Landscape Association. 70:39.

Interpretive Summary: Bacterial gall is a relatively new disease problem on Loropetalum cultivars in commercial plant nurseries. This research established rates of commercial disinfestants that can be used by Loropetalum growers to treat contaminated production areas. Clorox Germicidal Bleach, Green Shield II, KleenGrow, and Virkon S will effectively kill the bacterial pathogen on steel surfaces. Clorox Germicidal Bleach and Virkon S will effectively kill the bacteria on pressure-treated wood surfaces, and Clorox Germicidal Bleach will effectively kill the bacteria on Loropetalum stems. Loropetalum vegetative stem cuttings have been shown to be tolerant of bleach treatment, but this will be tested further in the future.

Technical Abstract: Bacterial gall is a relatively new disease problem on Loropetalum cultivars in commercial plant nurseries. Currently, few products have been tested for their efficacy to kill the bacterial pathogen, Pseudomonas amygdali pv. loropetali. Several commercial disinfestants were tested on stainless steel, pressure-treated wood and Loropetalum stem surfaces. Based on these trials, EPA label recommended rates of Clorox® Germicidal Bleach, Green Shield® II, KleenGrow™, and Virkon® S will disinfest metal surfaces of P. amygdali pv. loropetali, while only Clorox® Germicidal Bleach and Virkon® S will comparably disinfest pressure-treated wood surfaces. Clorox® Germicidal Bleach appears to be suitable for treating vegetative stem cuttings, but additional research is needed before this practice can be recommended. This research established rates of commercial disinfestants that can be used by Loropetalum growers to treat contaminated production areas. University Extension workers and crop advisers can incorporate this information into their recommendations.