Submitted to: Mycologia
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 6/29/2001
Publication Date: N/A
Interpretive Summary: In North America and Europe a serious disease of commercially grown mushrooms is known as "green mold." This disease is caused by a species of Trichoderma that is similar to a species used in the biocontrol of plant disease-causing fungi. There has been considerable confusion in distinguishing the Trichoderma causing the green mold epidemic from the Trichoderma used in biological control. Using molecular, morphological and cultural data, Samuels and colleagues have compared isolates of Trichoderma causing green mold with those used in biological control and can readily separate these different species. The Trichoderma causing green mold in cultivated mushroom beds is named as a new species and is described and illustrated. Molecular data shown clearly that it is different from other species of Trichoderma. A key is provided for the identification of Trichoderma species commonly found in cultivated mushroom beds. This paper will allow those attempting to control green mold of cultivated mushroom to distinguish the disease-causing species of Trichoderma from harmless ones.
Technical Abstract: Trichoderma aggressivum sp. nov. and T. aggressivum f. europaeum f. nov. are described. These forms are the cause of green mold epidemic in commercially grown Agaricus bisporus in North America and Europe, respectively. In the literature they have been reported as T. harzianum biotypes TH 4 and TH 2, respectively. They are strongly separated from their closest relative, T. harzianum, in sequences of the ITS-1 region of nuclear rDNA and an approximately 689 base pair fragment of the protein coding translation elongatin factor gene (EF-1a). They are distinguished from the morphologically similar T. harzianum and T. atroviride (the latter also known as biotype TH 3)most readily by rate of growth. Of these, only T. harzianum grows well and sporulates at 35 C. Trichoderma atroviride is the slowest growing. Trichoderma aggressivum f. aggessivum and f. europaeum are effectively indistinguishable phenotypically although they have subtly different growth rates at 25 C on SNA and statistically significant micromorphological differences. Expanded descriptions of T. harzianum and T. atroviride are provided. A key to Trichoderma species commonly found associated with commercially grown A. bisporus is provided.