The use of microorganisms to control plant diseases has
been practised during the last century. This strategy as an
environmentally friendly alternative to chemical pesticides
has gained attention especially during the last decades.
Bacteria, fungi and protozoa have been suggested to combat
pests in below- and above-ground plant material, and
several biological control agents (BCA) are on the market
today in the USA (http://www.epa.gov/pesticides/biopesticides/)
and in other countries (http://www.agrobiologicals.com)