Trans-cinnamic acid and Xenorhabdus szentirmaii metabolites synergize the potency of some commercial fungicides

• Published in: Journal of invertebrate pathology 2017-05, Vol.145, p.1-8
• Main Authors: Hazir, Selcuk, Shapiro-Ilan, David I., Bock, Clive H., Leite, Luis G.
• Format: Article
• Language: English
• Subjects: Antifungal; Bacterial metabolites; Cinnamates - pharmacology; Entomopathogenic nematodes; Fungi - drug effects; Fungicide; Fungicides, Industrial - pharmacology; Pest Control, Biological - methods; Photorhabdus; Phytopathogens; Plant Diseases - microbiology; Plant Diseases - prevention & control; Synergy; Xenorhabdus; Xenorhabdus - metabolism
• ISSN: 0022-2011; 1096-0805
• DOI: 10.1016/j.jip.2017.03.007

[Display omitted] •Potential for fungicidal synergy was assessed in bacterial metabolites.•Trans-cinnamic-acid (TCA) and Xenorhabdus szentirmaii metabolites were tested.•Those metabolites (derived from X. szentirmaii) and TCA are especially potent.•Certain combinations of metabolites with commercial fungicides resulted in synergy.•Fungal disease suppression may be enhanced through these synergies. Development of novel approaches for the control of fungal phytopathogens is desirable. In this study we hypothesized that the combination of commercial fungicides with certain enhancing agents could result in synergistic levels of control. Prior research has indicated that trans-cinnamic-acid (TCA), a metabolite of the bacteria Photorhabdus luminescens and metabolites of Xenorhabdus szentirmaii are particularly toxic to various phytpathogenic fungi when compared to metabolites of other Xenorhabdus or Photorhabdus spp. In this study we explored the efficacy of commercial fungicide interactions when combined with either TCA or X. szentirmaii. Fungicides (active ingredient) included Abound® (Azoxystrobin), Serenade® (Bacillus subtilis), Elast® (dodine), Regalia® (extract of Reynoutria sachalinensis), Prophyt® (potassium phosphite) and PropiMax® (propiconazole). In laboratory experiments, singly-applied or combined agents were assessed for fungicidal activity against four plant-pathogenic fungi, Monilinia fructicola, Rhizoctonia solani, Colletotrichum gloeosporioides and Fusarium oxysporum. Fungicidal activity was measured by the phytopathogen’s growth on potato dextrose agar with and without fungicide. The interactions between fungicidal agents were determined as antagonistic, additive or synergistic. For suppression of M. fructicola, synergy was observed between TCA when combined with certain concentrations of Elast®, PropiMax®, Regalia®, Prophyte® or Serenade®, and for combinations of X. szentirmaii with Abound®. For suppression of R. solani, synergy was observed between TCA combined with Regalia® or Serenade®. Additionally, when TCA was combined with X. szentirmaii synergistic levels of suppression to M. fructicola were observed. Other combinations of TCA or X. szentirmaii with the fungicides or using alternate concentrations were either additive or occasionally antagonistic in nature. Our results indicate that TCA and X. szentirmaii can each act as strong synergists to enhance fungicidal efficacy. These results may be used to reduce negative environmental impact