Potential of Three Plant Extracts in Suppressing Potato Dry Rot Caused by <i>Fusarium incarnatum</i> Under Normal and Cold Storage

The potato (<i>Solanum tuberosum</i> L.) is one of the most widely consumed vegetable crops worldwide. During storage, potato tubers are vulnerable to various phytopathogenic fungi. Dry rot, caused by <i>Fusarium incarnatum</i>, is a common and serious disease that affects potato tubers, leading to partial or complete decay during storage. The current study assessed the effectiveness of three ethanolic extracts including cinnamon bark (CIB), clove buds (CLB), and avocado seeds (AVS) in controlling potato dry rot under both normal and cold storage conditions. In vitro bioassay demonstrated that all tested extracts exhibited a dose-dependent fungistatic effect against <i>F. incarnatum</i>, with inhibition percentages of 83.33% for CIB, 72.22% for CLB, and 67.77% for AVS at the highest tested concentration. Moreover, dipping potato tubers in the tested extracts markedly reduced the severity of dry rot disease under both normal and cold storage conditions. Additionally, treated tubers showed increased activities of defense-related enzymes, including catalase, peroxidase, polyphenol oxidase, and phenylalanine ammonia-lyase. Furthermore, there were higher levels of total soluble phenolics and flavonoids, along with an increase in lignin content and a reduction in the weight loss of stored potato tubers compared to the control group. Moreover, the extracts mitigated infection stress and lowered malondialdehyde levels in the treated potato tubers. These extracts show potential as environmentally friendly alternatives to chemical fungicides for managing potato dry rot caused by <i>F. incarnatum</i> under normal and cold storage.