Madar (Tunis) - Olive knot disease, known in Tunisia as olive tuberculosis, has infected about 120,000 trees in the Melloulech delegation and the El Aitha area of Tunisia's Mahdia governorate, out of 433,000 trees recorded there, or nearly 28%, with 4,000 showing severe symptoms, plant protection director Mouna Mahafedhi said, according to the daily La Presse on Saturday, November 7, 2026.
Speaking on Express FM, the official of the General Directorate of Plant Health and Control of Agricultural Inputs said the bacterial disease has been known since the 1980s. It mainly affects olive trees but can also develop on oleander and jasmine, which act as secondary hosts.
To limit its spread, a mill has been assigned to process olives from infected trees and the harvest has been brought forward. After the harvest, the agriculture ministry plans, with the parties concerned, to prune the most severely infected trees and burn them on site, and to treat infected trees with a copper-based product.
Mahafedhi sought to reassure producers and consumers, saying tests by the National Oil Office on oil from infected trees showed the same quality and composition as oil from healthy olives.
The disease mainly shows as swellings and tumours on branches. It is favoured by high humidity, especially in coastal areas, by wounds from hail or from beating branches during the harvest, and by pruning with tools that have not been disinfected.
Cases have also been reported on olive trees planted in front of homes in several Sahel localities, including Teboulba in Monastir governorate, where municipalities will apply the same protocol. The official urged farmers to buy seedlings only from nurseries inspected by the ministry.
