Disease-Suppressive Soils. The
microflora of disease-suppressive soils is
usually dominated by antagonistic microorganisms that produce copious
amounts of antibiotics. These include
fungi of the genera Penicillium, Trichoderma, and Aspergillus, and actinomyce-
tes of the genus Streptomyces. The antibiotics they produce can have biostatic
and biocidal effects on soil-borne plant
pathogens, including Fusarium which
would have an incidence in these soils of
less than 5 percent.