Biological Control of Seedling Diseases

Seedlings of economically important crop plants are attacked by various soilborne pathogenic fungi, such as Pythium, Fusarium, Rhizoctonia, Phytopthora , and others, which cause either seed rot before germination or seedling rot after germination, resulting in billions of dollars in cumulative crop losses. These diseases are often termed preand postemergence damping-off, or seedling blights Greenhouse crops grown in soilless cultures, as well as field crops, are susceptible to soilborne fungal pathogens, resulting in considerable economic losses. Currently, the most widely used control measure for suppressing soilborne diseases is the use of environmentally hazardous fungicidal treatment of seed, seedlings, or soils. However, problems encountered, such as development of pathogen resistance to fungicides, inability of seed-treated fungicides to protect the roots of mature plants, rapid degradation of the chemicals, and a requirement for repeated applications, have given impetus to alternative remedies (1 ).