In crop production over half of potential crop yield is lost to plant pathogens, most of it to fungal disease. In storage, up to one third of the harvested product can be lost to post-harvest disease, again mostly due to the activities of fungi. Post-harvest losses can be reduced by storage of products at low temperatures and low moisture levels. Although plants are susceptible to fungal pathogens, animals and humans are far less susceptible to fungal infections. There are many barriers to fungal infection in animals and man.
Skin is a physical barrier to infection.
Mucous membranes and their secretions are also effective barriers, and the human and animal immune system which includes cell mediated immunity and humoral immunity, is highly effective against fungi. Furthermore, within the body the acidity of the upper GI tract renders the habitat untenable to fungi. To some extent there is also a resident microflora on all surfaces of the body which acts to occupy the niche through competition and antibiosis. There are usually a number of reasons for fungal infections. Any condition that suppresses the immune system will increase the risk of fungal infections.