Efficacy of Low-Toxicity Alternatives for Citrus Disease Management: Potassium Sorbate and Sodium Benzoate against Alternaria alternata
2025
Lamyaa Zelmat | Meriem Hamrani | Oussama Fariss | Zineb Abbad | Mohamed Dahman | Abdelali Samdi | Mohammed Ibriz | Mohammed El Guilli
The integration of generally recognized as safe (GRAS) salts as low-toxicity solutions represents a crucial eco-friendly alternative to fungicides, harnessing their potent antimicrobial effects against various crop pathogens. In this study, the effectiveness of potassium sorbate, sodium benzoate, sodium bicarbonate, and sodium tetraborate was investigated against Alternaria alternata, a significant pathogen causing diseases worldwide in citrus. The inhibitory effects of various salt concentrations on this pathogen were evaluated in vitro using modified potato dextrose agar (PDA) and in vivo through artificial inoculation of ‘Maroc Late’ orange fruits, under both curative and preventive treatments. Initial screening of different active ingredients against three A. alternata isolates established imazalil as a commercial reference for comparative analysis. Results showed that potassium sorbate and sodium benzoate were the most potent inhibitors, suppressing the fungus in vitro by 71% and 67% at 2,000 ppm, respectively, revealing a very low value of IC50 (3 ppm). These two salts yielded comparable outcomes to imazalil (100% suppression) in the curative treatment, achieving significant reductions in severity of 80% and 100% at a low concentration of 2% (w/v). Additionally, fruits treated preventively with 4% (w/v) potassium sorbate and sodium benzoate reduced disease symptoms by up to 100%. The current study highlights GRAS salts that are similarly effective to imazalil and could serve as alternatives to conventional fungicides registered for managing Alternaria diseases of citrus.
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