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Published on: December 5, 2020
Interaction between Pseudomonas fluorescens isolates and thiabendazole in the control of gray mold of apple
A Mikani1, H R Etebarian, H Aminian
1Department of Plant Protection, Abourayhan Campus, University of Tehran, P.O. Box 11365/4117, Tehran, Iran.
Abstract:
Five isolates KW, 16P, 8, 11 and 7 of Pseudomonas fluorescens and fungicide thiabendazole were evaluated for control of gray mold of apple caused by Botrytis mali. Dual culture, cell free metabolite and volatile test showed that all five isolates of Pseudomonas fluorescens tested inhibited growth of the pathogen. Inhibition varied from 28.9-85.7% in dual culture, from 62-94.6% in cell free metabolite and from 45.9-87.9% in volatile test. Apples were wounded and inoculated with a 20 microL Botrytis mali (10(5) conidia mL(-1)) combined with a range of concentration of fungicide. Thiabendazole controlled gray mold by over 83% at 5 microg mL(-1). Pseudomonas fluorescens isolates prevented B. mali decay from expanding to more than 49.4% at 20 degrees C. Thiabendazole was combined with bacteria to control gray mold of apple. Mixing of thiabendazole and bacterial isolates provide more than 90.2% control at concentrations 5 microL mL(-1) and 10(7) CFU mL(-1), respectively, on Golden delicious apples. A combination of thiabendazole and Pseudomonas fluorescens isolate 11 at concentration 10 microg mL(-1) and 1 x10(7) CFU mL(-1), respectively controlled gray mold by 100%. Thiabendazole was not bactericidal and had no effect on five isloates of Pseudomonas fluorescens.
Insights
Five Pseudomonas fluorescens isolates and thiabendazole effectively controlled apple gray mold caused by Botrytis mali. Combining the fungicide and bacteria achieved 100% disease control, demonstrating a potent biocontrol strategy.
Area of Science:
- Agricultural Science
- Plant Pathology
- Microbiology
Background:
- Gray mold, caused by Botrytis mali, is a significant postharvest disease affecting apples.
- Effective disease management strategies are crucial for reducing apple losses.
Purpose of the Study:
- To evaluate the efficacy of Pseudomonas fluorescens isolates and the fungicide thiabendazole, individually and in combination, for controlling gray mold in apples.
- To determine the synergistic effects of combining biological control agents with chemical fungicides.
Main Methods:
- In vitro inhibition assays (dual culture, cell-free metabolite, volatile tests) were used to assess the antagonistic potential of five P. fluorescens isolates against B. mali.
- In vivo efficacy was tested on wounded Golden Delicious apples inoculated with B. mali and treated with varying concentrations of thiabendazole and/or P. fluorescens isolates.
- The impact of thiabendazole on the viability of P. fluorescens isolates was also investigated.
Main Results:
- All five P. fluorescens isolates demonstrated significant inhibition of B. mali growth in vitro, with inhibition rates ranging from 28.9% to 94.6% depending on the method.
- Thiabendazole alone provided over 83% control at 5 µg/mL, while P. fluorescens isolates reduced decay by up to 49.4% at 20°C.
- A combination of thiabendazole (5 µL/mL) and P. fluorescens (10^7 CFU/mL) achieved over 90.2% control, with isolate 11 and thiabendazole (10 µg/mL) resulting in 100% control.
- Thiabendazole was found to be non-bactericidal to the tested P. fluorescens isolates.
Conclusions:
- Pseudomonas fluorescens isolates exhibit strong antagonistic activity against Botrytis mali, making them promising biocontrol agents.
- The combination of thiabendazole and P. fluorescens offers a synergistic approach for superior gray mold control in apples.
- This integrated strategy presents a sustainable and effective method for managing apple gray mold, potentially reducing reliance on chemical fungicides.
