weather is the preferred climate for banana cultivation, but it is also the environment where the pathogen thrives: hot and humid, with plenty of rainfall to aid in dispersal. The optimal environment of the pathogen is similar to that of the banana tree. The fungus infects mature banana leaves and will continue to cause infection without proper control. In the early stages of the infection of the plant, the lesions have a rusty brown appearance and appear to be faint, paint-like specks on the leaves. They become more visible on the undersides of the banana leaf as the lesions and leaves grow. The spots on the undersides of leaf are the fungus itself. The sign of the pathogen consists of the ascocarp which holds the ascospores used for dissemination to infect healthy new plants when the environment is conducive. The pathogen then survives on dead plant tissue as mycelium. The dimensions of the lesions are characteristically with a well defined wall surrounding it. After further development, they become darker, sink into the leaf, and turn into depressions. The depressions themselves and the chlorosis surrounding them are the visible symptoms of the plant pathogen. They eventually will merge, causing the rapid decline of plant morphological and physiological function. Leaves with large infectious lesions will start to degrade and collapse because the leaf spots interrupt the plant's ability to perform photosynthesis, leading to the ultimate death of the plant. The yellow leaf streak pathogen is in the same genus as that of black leaf streak. Yellow leaf streak shows smaller, yellow-green lesions that appear on top of the leaves. Management There are several ways to control black Sigatoka, either by cultural and chemical means or by genetic engineering. Cultural control includes the destruction of leaves that have been infected with M. fijiensis. This will help reduce the initial (ascospores) and secondary (conidia) spread of inoculum of new plant leaves and interrupt the pathogen's polycyclic disease cycle. Another way of reducing primary/secondary inoculums is via efficient drainage and irrigation. Keeping the environment around the plants at low humidity helps keep the ascospores/conidia produced by the pathogen from being dispersed in the water draining towards other healthy, susceptible hosts. Other techniques include planting the banana trees more than above sea level and practicing multi-cropping, mixing banana with other trees or vegetation. One form of chemical control is applying fungicides. This is a preemptive control