Abstract: This invention provides a novel endophytic fungus, Muscodor, that produces a mixture of volatile antibiotics with activity on specific plant pathogens, bacteria, nematodes and insects. Also provided is a method for treating or protecting plants, soil and seeds from microbial infections comprising applying an effective amount of a volatile antibiotic producing Muscodor sp. The invention also relates to fungicidal, bactericidal, insecticidal and nematicidal compositions comprising this novel Muscodor strain and the antibiotics and metabolites produced by this strain either alone, or in combination with other chemical and biological pesticides. Also provided is a method for identifying and isolating related gas producing fungi.