Fungi is a group of organisms that includes the yeasts, moulds, and the mushrooms.

Harmful effects of fungi to humans
A number of moulds and yeasts cause human and animal diseases. For example, species of Aspergillus, Fusarium, and Sporothrix are opportunistic pathogens and easily infect individuals with weak immune systems.

A number of other moulds are well recognized causes of allergic reactions. For example Penicillium roquefortii and Aspergillus clavatus are causes of pulmonary allergy in the cheese and brewery industries respectively. Arthrinium casues skin allergies of cane harvesters.

Apart from infection and allergies, some moulds produce toxic compounds that are harmful to both humans and animals. The best known of these toxins is aflatoxin. Aflatoxin is mainly produced by some species of Aspergillus such as Aspergillus flavus and Aspergillus parasitica. Aflatoxin is a powerful trigger of cancer (i.e., it is carcinogenic).


Harmful effects of fungi to plants
Majority of plant diseases are caused by fungi. The plant diseases caused by fungi range from tissue death to vascular wilting. Fungi cause both field and storage losses of agricultural products.