Evolving Concepts of Biological Control of Plant Pathogens

Although numerous successful agricultural applications of biological control of plant pathogens have been devised, there remain many uncharted mech­ anisms that have evolved and are functioning undetected in the natural world. The search for these biological-control systems is in its infancy, having largely taken place in the last twenty years. Biological control is the decrease of inoculum or the disease-producing activity of a pathogen accomplished through one or more organisms, includ­ ing the host plant but excluding man. The term was used in relation to plant pathogens by C. F. von Tubeuf in 1914, and to insects by H. S. Smith in 1919, with the broad simplistic interpretation of control of one organism by another, exclusive of man. Since this paper reviews concepts of the organized corpus of biocontrol, citations have been kept to a minimum, but some investigations are identified by author and date. A few general references (1-13) may be consulted for specific details and other relevant citations.