Effects of Pesticides on the Reduction of Plant and Human Pathogenic Bacteria in Application Water

Abstract

Overhead spray applications of in-field tomato treatments dissolved in aqueous solutions have specific pest targets (fungal, bacterial, insect, or other). Any organism present in the solution or on treated plant surfaces that is not a specific target of the application is unlikely inactivated and can instead be spread through the phyllosphere. In this laboratory study, commercially labeled pesticides (including Actigard 50WG, Bravo Weather Stik 6F, Cabrio 20EG, Kasumin, Kocide 3000 46WG, Oxidate 27L, Penncozeb 75DF, ProPhyt 54.5L, Stimplex 100L, Firewall, 22.4WP, and Tanos 50DF) in common use in commercial tomato production fields of the Eastern Shore of Virginia were investigated for activity against in vitro bacterial contamination of pesticide application waters. Pesticides of interest were tank mixed individually with one of the plant pathogens Ralstonia solanacearum, Xanthomonas campestris pv. vesicatoria, Pseudomonas syringae pv. tomato, Erwinia carotovora subsp. carotovora, or one of two serovars (Newport and Montevideo) of the human pathogen Salmonella enterica to assess reduction values during the average time between mixing and initial application. Observations suggested that while some treatments had a noticeable effect on population levels, only the oxidizer, peroxyacetic acid, showed significant and consistent levels of suppression against all bacteria investigated, at levels that could have practical implications.

Effect of pesticide application on Salmonella survival on inoculated tomato leaves

“…A previous study indicated that copper has antibacterial effects against Salmonella (Zhu, Elguindi, Rensing, & Ravishankar, 2012); however, in the study reported here, the application of copper hydroxide did not result in a significant reduction of Salmonella concentrations on leaf surfaces (Table 1). This finding is supported by existing literature evaluating the use of copper-based compounds against epiphytic Salmonella populations ( Mahovic et al, 2013;Ottesen et al, 2015). In contrast, Salmonella concentration had a significant log reduction in the ground leaves after copper hydroxide treatment, compared to the control (0.79 ± 0.16, p ≤ 0.05).…”

“…Copper hydroxide is a widely used pesticide labeled to suppress levels of several bacterial and fungal diseases in tomatoes. Copper‐containing materials are broad spectrum, multi‐site, and active on bacterial pathogens through disruption of cellular proteins and enzymes, such as aggregation of ROS‐independent protein and inhibition of peptidoglycan LD‐transpeptidases (Baena, Marquez, Matres, Botella, & Ventosa, 2006; Mahovic, Gu, & Rideout, 2013; Ritchie, 2004). Acibenzolar‐ S ‐methyl stimulates the plant's natural defenses through mimicking the natural systemic activated resistance (SAR) response, which allows the host plant to ward off infection from certain bacterial and fungal pathogens (Graves & Alexander, 2002).…”

“…PAA is also used as a surface sanitizer and postharvest water treatment additive to reduce potential cross‐contamination in dump tanks/flumes (Mari, Bertolini, & Pratella, 2003; Sargent, Ritenour, Brecht, & Bartz, 2000; Sisquella, Casals, Viñas, Teixidó, & Usall, 2013). Streptomycin is an aminoglycoside antibiotic with antibacterial activity, and is labeled for control of bacterial diseases, especially during greenhouse transplant production (Mahovic et al, 2013).…”

Survival and growth of foodborne pathogens in pesticide solutions routinely used in leafy green vegetables and tomato production

“…Chlorothalonil (Bravo) had no significant effect on either of the pathogens. Such results are in agreement with those reported by Mahovic et al . but different from the results of Guan et al .…”

Constitutive and Secretory Expression of the AiiA in <i>Pichia pastoris</i> Inhibits <i>Amorphophallus konjac</i> Soft Rot Disease

“…Current protective measures rely on chemical control, producing bactericide-resistant pathogens and other undesirable environmental consequences [22]. Alternative strategies must be found to protect A. konjac crops from Erwiniae pathogens.…”