Trichoderma species associated with the green mold epidemic of commercially grown Agaricus bisporus

• Published in: Mycologia 2002, Vol.94 (1), p.146-170
• Main Authors: Samuels, Gary J., Dodd, Sarah L., Gams, Walter, Castlebury, Lisa A., Petrini, Orlando
• Format: Article
• Language: English
• Subjects: Agaricus bisporus; Biological taxonomies; Chlamydospores; Conidia; conidiophores; fungal anatomy; green mold disease; host plants; Hypocrea; Hypocrea atroviride; Hypocrea lixii; Hypocreales; internal transcribed spacers; ITS; molds (fungi); molecular sequence data; molecular systematics; Mushroom compost; Mushrooms; new species; nucleotide sequences; Orchard soils; Phenotypes; phylogeny; plant pathogenic fungi; plant taxonomy; ribosomal DNA; Soil fungi; Systematics; taxonomic keys; translation elongation factor 1 alpha gene; translation elongation factor 1 alpha gene (EF-1α); Trichoderma; Trichoderma aggressivum; Trichoderma aggressivum f. europaeum; Trichoderma atroviride; Trichoderma harzianum
• ISSN: 0027-5514; 1557-2536
• DOI: 10.1080/15572536.2003.11833257

Trichoderma aggressivum sp. nov. and T. aggressivum f. europaeum f. nov. are described. These forms cause the 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 bp fragment of the protein coding translation elongation factor gene (EF-1α). 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, while T. atroviride is the slowest growing. Trichoderma aggressivum f. aggressivum and f. europaeum are effectively indistinguishable morphologically although they have subtly different growth rates at 25 C on SNA and statistically significant micromorphological differences. Based on findings of this study, descriptions of T. harzianum and T. atroviride are expanded. A key to Trichoderma species commonly found associated with commercially grown A. bisporus is provided.