New Study Shows Decreasing Effectiveness Of Fungicides To Control The Devastating Black Sigatoka Disease Of Banana The fungus Pseudocercospora fijiensis causes black leaf streak disease or Black Sigatoka of banana, which is the most damaging leaf disease of bananas worldwide. An analysis of 592 P. fijensis isolates from seven banana-producing countries on three continents shows how P. fijensis is evolving to insensitivity to azole fungicides due to the heavy use of pesticides. The results of the study have been published in Pest Management Science and underscore the need to stop this vicious circle by developing alternative disease control methods and new banana varieties.