Biological Control of Potato Bacterial Wilt (Ralstonia solanacearum) Using Selected Plant Extracts

The current study evaluated the effect of methanol and water extracts of tobacco (Nicotiana tabacum L.), wild marigold (Tagetes minuta L.), and garlic (Allium sativum L.) at 50 mg·mL⁻¹ applied at different frequencies (weekly, biweekly, and monthly) on the control of potato bacterial wilt under field conditions (two growing seasons in 2021). Weekly and biweekly application of methanol extracts from tobacco and wild marigold showed higher efficacy of biological control of the pathogen (58% and 57%) on aerial parts of potato plants than monthly application (48%). In potato tubers, weekly and biweekly application of methanol extracts caused higher biological control efficacy (75.92% and 67.39%) than monthly application (52.49%). Weekly and biweekly application of methanol extracts of tobacco and wild marigold also reduced postharvest infection and postharvest yield losses caused by potato bacterial wilt during the storage period, among other treatments. These experiments conclude that weekly or biweekly application of methanol extract from tobacco and wild marigold at 50 mg·mL⁻¹ is a practical approach to control potato bacterial wilt in the field and storage.