(Terror of Bengal) 'Water hyacinth' is controlled by using the...

Water hyacinth (Eichhornia crassipes), commonly known as the 'Terror of Bengal', is a highly invasive aquatic weed.

It is biologically controlled by using specific pathogenic fungi that act as mycoherbicides. The fungi used for its control include Fusarium spp. (such as Fusarium pallidoroseum), Alternaria eichhorniae, and Cercospora rodmanii.

Looking at the other options:
Phytophthora palmivora is used to control milkweed vine.
Alternaria crassa is used to control Jimsonweed (Datura stramonium).
Trichoderma spp. are used as biofungicides to control plant diseases caused by other pathogenic fungi.

Therefore, Fusarium spp. is the correct answer.

Answer: Fusarium spp