The study looked at how certain soil microorganisms affect the growth of a fungus that causes wilt in pigeon-pea plants. They found that some microorganisms can inhibit the growth of the fungus by changing the environment it grows in, rather than by using up its food or producing toxins. One microorganism, Rhizopus nigricans, was particularly effective at reducing the incidence of wilt because it grows quickly. When mixed with other microorganisms, it was even more effective. However, another microorganism, Aspergillus terreus, actually made the fungus more harmful.