One of the diseases caused by fungi is coffee leaf rust. Coffee leaf rust is a fungal disease that affects coffee plants, causing leaves to turn yellow and fall off. The disease is caused by a fungus called Hemileia vastatrix, which infects the leaves of the coffee plant and reduces its ability to produce coffee beans.
Cassava mosaic, leaf blight of cassava rosette, and groundnut disease, on the other hand, are caused by viruses and bacteria, not fungi. Cassava mosaic is caused by a virus, while leaf blight of cassava rosette is caused by bacteria. Groundnut disease is caused by a fungus, but it is not one of the options given in the question.
In summary, coffee leaf rust is the disease caused by fungi among the options given. It is a fungal disease that affects coffee plants, while the other options are caused by viruses or bacteria.