Safely Applying Fungal Treatments to Fruits After Harvest

Greg Howard
3rd June, 2024

Safely Applying Fungal Treatments to Fruits After Harvest

The non-wounding contact method successfully infected 90% of fungicide-treated apples with a resistant strain of P. expansum (b), resulting in steadily progressing disease lesions over a two-week period (a, c).

Image adapted from: Sbodio et al. / CC BY (Source)

Key Findings

  • Researchers at the University of California, Davis, developed a reliable method to simulate disease spread in stored fruits
  • The study tested oranges, tomatoes, and apples against common postharvest pathogens like Penicillium and Botrytis
  • The new method showed over 80% disease incidence in most trials, proving its effectiveness in studying fruit-pathogen interactions
Fungal pathogens significantly impact the quality of fruits and vegetables at different stages of the supply chain, leading to substantial food losses. Understanding how these persistent fungal infections occur and progress in postharvest conditions is essential to developing effective control strategies. A recent study conducted by researchers at the University of California, Davis[1], has developed a reliable and consistent inoculation protocol to simulate disease spread from infected fruits to adjacent healthy fruits during postharvest storage. In this study, different combinations of fruit commodities, including oranges, tomatoes, and apples, were tested against impactful postharvest pathogens such as Penicillium digitatum, Penicillium italicum, Botrytis cinerea, and Penicillium expansum. The researchers assessed the efficacy of their protocol using fruits treated with various postharvest methods and multiple isolates for each pathogen. They optimized the source of infected tissue and incubation conditions for each fruit-pathogen combination. Disease incidence and severity were quantitatively evaluated to study infection success and progression. At the final evaluation point, 80% or higher disease incidence rates were observed in all trials except for the fungicide-treated oranges inoculated with fungicide-susceptible Penicillium spp. isolates. Although disease incidence was lower in that particular scenario, it is noteworthy that the pathogen was still able to establish itself under unfavorable conditions, indicating the robustness of the methodology. Additionally, multispectral imaging was used to detect early P. digitatum infections in oranges before the disease became visible to the naked eye but after the pathogen was established. This study ties together previous findings on the management of postharvest diseases. For instance, earlier research demonstrated the effectiveness of Bacillus subtilis JK-14 in controlling postharvest diseases in peaches caused by Botrytis cinerea and Alternaria tenuis[2]. The new study expands on this by providing a robust protocol for simulating disease spread in various fruits, thereby facilitating the study of fruit-pathogen interactions and the assessment of innovative control strategies. Botrytis cinerea, a pathogen included in this study, has been extensively researched due to its impact on over 200 crop hosts worldwide[3]. It is known for its genetic plasticity, which makes it resistant to many classes of fungicides. This study's methodology could help in understanding how B. cinerea spreads and establishes itself in postharvest conditions, providing insights that could lead to more effective control strategies. The findings also align with previous research on the biology and epidemiology of Botrytis cinerea in strawberries[4]. Despite intensive efforts, breeding strawberries for resistance to grey mould caused by B. cinerea has not been successful. The new protocol could be used to test various control strategies, including biological controls, to manage grey mould in strawberries and other fruits. In conclusion, the study conducted by the University of California, Davis, developed a non-invasive inoculation strategy that can recreate infections caused by contact or nesting in postharvest. The high disease incidence and severity values observed across different fruit commodities and fungal pathogens demonstrate the robustness, efficacy, and reproducibility of the developed methodology. This protocol has the potential to be tailored for other pathosystems and can facilitate the study of fruit-pathogen interactions and the assessment of innovative control strategies.

FruitsPlant ScienceMycology

References

Main Study

1) Non-wounding contact-based Inoculation of fruits with fungal pathogens in postharvest.

Published 2nd June, 2024

https://doi.org/10.1186/s13007-024-01214-2

Related Studies

2) Identification of the Fungal Pathogens of Postharvest Disease on Peach Fruits and the Control Mechanisms of Bacillus subtilis JK-14.

https://doi.org/10.3390/toxins11060322

3) Botrytis cinerea: the cause of grey mould disease.

https://doi.org/10.1111/j.1364-3703.2007.00417.x

4) Grey mould of strawberry, a devastating disease caused by the ubiquitous necrotrophic fungal pathogen Botrytis cinerea.

https://doi.org/10.1111/mpp.12794


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