Phytopathology (2019) 109, 52-62

Y.-Y. Liao, A.L. Strayer-Scherer, J. White, A. Mukherjee, R. De La Torre-Roche, L. Ritchie, J. Colee, G.E. Vallad, J.H. Freeman, J.B. Jones and M.L. Paret (2019)
Nano-magnesium oxide: A novel bactericide against copper-tolerant Xanthomonas perforans causing tomato bacterial spot
Phytopathology 109 (1), 52-62
Abstract: Bacterial spot caused by Xanthomonas perforans causes significant damage on tomato in Florida. Due to the presence of copper (Cu)-tolerant X. perforans strains, Cu bactericides are not effective in disease management. Hence, there is a critical need to find alternatives for Cu. Antibacterial activity of magnesium oxide (Nano-MgO), and other metal oxide nanoparticles, were evaluated against a Cu-tolerant and -sensitive X. perforans strain. In vitro experiments demonstrated high antibacterial activity of Nano-MgO against both strains compared with the commercial Cu. The minimum inhibitory concentration of Nano-MgO is 25 µg/ml and the minimum bactericidal concentration is 100 µg/ml against a Cu-tolerant X. perforans strain after 4 h of exposure. Structural changes in the bacterial membrane following exposure to Nano-MgO treatments compared with the controls were observed using transmission electron microscopy. In two greenhouse experiments with a Cu-tolerant strain, bacterial spot severity was significantly reduced by Nano-MgO at 200 µg/ml compared with Cu-ethylene bis-dithiocarbamate (grower standard), and the untreated control (P = 0.05). In three field experiments, Nano-MgO at 200 µg/ml significantly reduced disease severity with no negative impact on yield compared with the untreated control. Inductively coupled plasma mass spectrometric analysis of the fruit confirmed that Nano-MgO application did not lead to the accumulation of Mg, Cu, Ca, K, Mn, P, and S. This study is the first to demonstrate the potential of Nano-MgO against bacterial spot of tomato.
(The abstract is excluded from the Creative Commons licence and has been copied with permission by the publisher.)
Link to article at publishers website
Database assignments for author(s): Gary E. Vallad, Jeffrey B. Jones

Research topic(s) for pests/diseases/weeds:
control - general
pesticide resistance of pest

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Pest and/or beneficial records:

Beneficial	Pest/Disease/Weed	Crop/Product	Country	Quarant.
	Xanthomonas euvesicatoria	Tomato (Solanum lycopersicum)	U.S.A. (SE)