Black Sigatoka
Black Sigatoka is caused by the ascomycete, Mycosphaerella fijiensis. The pathogen produces conidia and ascospores, both of which are infective.
Black Sigatoka is common in warmer environments and formed under high moisture conditions, and are disseminated by wind, and in the case of conidia, also by rain and irrigation water.
What are the symptoms
The first symptoms of black Sigatoka disease are tiny, chlorotic spots that appear on the bottom surface of the 3rd or 4th open leaf.
The spots grow into thin brown streaks that are limited by leaf veins.
The color of the streaks becomes darker, sometimes with a purple tinge, and visible on the top surface.
The lesions then enlarge, becoming fusiform or elliptical, and darken to give the characteristic black streaking of the leaves.
Adjacent tissue often has a water-soaked appearance, especially under conditions of high humidity and streaks that are limited by leaf veins.
Impact to the crop
Severe infestation may lead to large necrotic lesions on the leaf surface and early drop of the leaf that may result in loss of photosynthetic capability leading to slow filling of fingers, reduced yields and premature ripening of fruits.
How to control
Black Sigatoka is controlled with frequent applications of fungicides and cultural practices, such as the removal of affected leaves, and adequate spacing of plants and efficient drainage within the plantation. For example, fungicide application includes the use of airplanes or helicopters, permanent landing strips and facilities for mixing and loading the fungicides, and the high recurring expense of the spray materials themselves.
Source:Bennett, R.S. and P.A. Arneson. 2003. The Plant Health Instructor. "Black Sigatoka of Banana and Plantains". Retrieved from: https://www.apsnet.org/edcenter/disandpath/fungalasco/pdlessons/Pages/BlackSigatoka.aspx
Ploetz, R.C. 2001. The Plant Health Instructor. "Black Sigatoka of Banana: The most important disease of a most important fruit". Retrieved from: https://www.apsnet.org/edcenter/apsnetfeatures/Pages/BlackSigatoka.aspx
