Black Sigatoka
Class: Fungi
Common Name
Black sigatoka
Scientific name
Pseudocercospora fijiensis (previously known as Mycosphaerella fijiensis)
Potential Hosts
Banana
Who am I?
Black sigatoka is a destructive fungal disease that affects all banana varieties. The fungus requires living plant tissue in order to complete its lifecycle but also has the ability to survive on dead plant residues. The fungus penetrates leaf tissue and continues to develop for a few weeks without causing damage to the tree.
Black sigatoka favours periods of heavy rainfall and high humidity. It is spread mainly by winds, splashes of water, and packaging materials that came in contact with infected plant parts. Infected crops may result in more than 50% of yield losses due to crop damages. Black sigatoka symptoms often include small chlorotic spots appearing on the underside of leaves. With time, spots expand and form thin brown streaks in the around the veins. When humidity conditions are high for a significant period of time, the whole leaf can become dry and die, which triggers fruit to ripen early.
Control measures
Cultural
*Sanitation: Make an effort to clean and maintain the fields’ close surroundings from weeds as often as possible. Remove and dispose of infected leaves.
Proper soil drainage: Standing water will promote the development and spread black sigatoka.
Conventional (Chemical)
When conditions for black sigatoka are favorable, apply frequent applications of fungicides in places that are high risk and in intervals of every 7 days. Some areas will require applications for up to 20 days.
The following are generic names of fungicides used in one or more parts of the world: azoxystrobin, propiconazole, tridemorph, bordeaux mixture, and methoxyacrylate.
Caution and careful notice should be taken when using any plant protection products (insecticides, fungicides, and herbicides). It is the grower’s sole responsibility to keep track of the legal uses and permissions with respect to the laws in their country and destination markets. Always read the instructions written on labels, and in a case of contradiction, work in accordance to the product label. Keep in mind that information written on the label usually applies to local markets. Pest control products intended for organic farming are generally considered to be less effective in comparison to conventional products. When dealing with organic, biologic, and to some extent a small number of conventional chemical products, a complete eradication of a pest or disease will often require several iterations of a specific treatment or combination of treatments.