The use of Fludioxonil against brown rot

Brown rot of pome and stone fruit is caused by phytopathogenic fungi of the genus Monilinia, which pose a significant threat to production and can cause economically significant losses on a global scale. The main method of controlling these pathogens is the fungicide application, as there are no other effective measures.

Sterol biosynthesis inhibitors, anilinopyrimidines, phenylpyrroles, and respiration inhibitors are used to regulate brown rot degradation, but it is necessary to combine them to achieve results. In this context, biological control agents can be an alternative to chemical pesticides in preventing brown rot during pre-harvest applications.

Controlling brown rot disease remains a challenge, despite the use of many registered fungicides or biofungicides, despite the high number of applications during the season: three to five sprays during the flowering period and one or two sprays before harvest. Fludioxonil is a non-systemic fungicide, which is considered low risk and therefore also used in integrated management protocols.

The objectives of the present study, conducted in Serbia, were to compare and ascertain the toxicity of Fludioxonil against selected isolates of M. laxa, M. fructigena and M. fructicola, to test its efficacy in detached fruit and to evaluate its effectiveness under practical control conditions.

Fludioxonil sensitivity testing was conducted in vitro on a total of 27 isolates, including 10 isolates of M. laxa, 8 isolates of M. fructigena and 9 isolates of M. fructicola. The experiment was conducted on sour cherries, plums and peaches. Fludioxonil showed a high level of efficacy in preventing Monilinia spp. infection in sour cherries, ranging from 84.9 to 91.9 percent.

However, the efficacy of the reference fungicide Signum was 82.7-92.2%, thus showing comparable results. Consequently, the efficacy of Fludioxonil on sour cherry fruit was only marginally reduced by the use of this product. The incidence of fruit degradation in the control plots of the sour cherry orchards was also higher than that in the peach and plum plots.

The researchers speculated that the lower efficacy of Fludioxonil in sour cherry may be the result of the higher disease pressure in the orchard. In addition, the EPPO protocol for evaluation of stone fruit decay does not require classification of fruit affected by Monilinia species.

It is also possible that sour cherry fruits were infected mainly with M. laxa, the species with the lowest sensitivity to Fludioxonil according to our in vitro experiments. This could be the reason for the slightly lower efficacy in the test on sour cherries. As the results showed, Fludioxonil was highly effective against Monilinia spp. both in the in vitro sensitivity test and when used under practical field conditions to control brown rot.

In light of these results and the reduced-risk classification, Fludioxonil is a viable option for the effective management of brown rot. The results also emphasized the importance of assessing the prevalence of Monilinia species and taking this information into account when developing crop protection strategies.

Future research will focus on identifying the most effective and optimal time for Fludioxonil application in the field, with the goal of reducing the overall number of applications. Future efforts will also focus on the potential integration of Fludioxonil with biofungicides to improve disease management strategies and reduce agricultural losses.

Source: Hrustić, J., Vojinović, U., Mihajlović, M. et al. Effectiveness of Fludioxonil, a New-Generation Reduced-Risk Fungicide, Against Brown Rot Pathogens. Curr Microbiol 81, 281 (2024). https://doi.org/10.1007/s00284-024-03808-4.
Image: UMN

Melissa Venturi
University of Bologna (IT)

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