Allaga, Henrietta

Geösel, András

Hatvani, Lóránt

Kredics, László

Kuti, K.

Manczinger, László

Vágvölgyi, Csaba

Hatvani Lóránt

Kredics László

Allaga Henrietta

Manczinger László

Vágvölgyi Csaba

Kuti K.

Geösel András

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Disease NoteDiseases Caused by Fungi and Fungus-Like OrganismsFirst Report of Trichoderma aggressivum f. aggressivum Green Moldon Agaricus bisporus in Europe. L. Hatvani, L. Kredics, H. Allaga,L. Manczinger, and C. Va´gvo¨lgyi, Department of Microbiology, Faculty ofScience and Informatics, University of Szeged, H-6726 Szeged, Hungary;and K. Kuti, A. Geo¨sel, and S. Istva´n, University, Faculty of HorticulturalScience, Department of Vegetable and Mushroom Growing, H-1118Budapest, Hungary. L. Hatvani and L. Kredics are joint first authors. Thiswork was supported by grants NKFI K-116475 and GINOP-2.2.1-15-2016-00006. Plant Dis. 101:1, 2017; published online as http://dx.doi.org/10.1094/PDIS-12-16-1783-PDN. Accepted for publication 28 February 2017.The white button mushroom (Agaricus bisporus) is the economicallymost important cultivated edible mushroom in Europe. The production ofA. bisporus can be seriously affected by so-called green mold disease, causedby Trichoderma aggressivum. This species has two biotypes: T. aggressivumf. europaeum, being responsible for Agaricus green mold problems inEurope, and T. aggressivum f. aggressivum, the causal agent of the disease inNorth America (Samuels et al. 2002). T. aggressivum f. europaeum has beenpreviously reported from Hungarian mushroom producing facilities as well(Hatvani et al. 2007). In December 2015, massive green mold epidemicsoccurred at a mushroom farm in central Hungary, cultivating the A. bisporusoff-white hybrid with nearly 100% crop loss in the affected mushroom beds.The farm used Phase III bulk compost and the symptoms were visible beforethe first flush. Both the compost and casing soil were completely colonizedby Trichoderma, with conspicuously visible mass of green conidia on thesurface. In the same year, a further outbreak was documented at a mushroomgrowing company in northeast Hungary in the cultivation of A. bisporus.Compost and casing soil samples were collected at both locations andTrichoderma strains were isolated from the samples on dichloran-rose bengalagar medium. Colony morphology of the pure cultured isolates on potatodextrose agar and conidiophore morphology examined by light microscopywere consistent with the genus Trichoderma and the species T. aggressivum(Samuels et al. 2002). Molecular identification was performed at the speciesand biotype level by sequence analysis of the ribosomal RNA internaltranscribed spacer (ITS) region amplified by the universal primers ITS1 andITS4 according to Andersson et al. (2009). Nucleotide BLAST analysisrevealed that all isolates share the same ITS sequence showing 100% identitywith the type strain of T. aggressivum f. aggressivum (DAOM 222156,GenBank NR_137299.1), and differing in three diagnostic nucleotide positionsfrom the type strain of T. aggressivum f. europaeum (CBS 100526, GenBankNR_145035.1), as well as from previous Hungarian isolates of the Europeangreen mold biotype (Hatvani et al. 2007). To confirm the pathogenicity of theisolate to A. bisporus, six mushroom bags filled with 2 kg Phase III compostwere inoculated with conidial suspensions (106 conidia/ml; 50 ml/bag) of theHungarian T. aggressivum f. aggressivum isolate SZMC 23834. The conidialsuspensions were thoroughly mixed into the compost before casing andsprayed onto the casing soil at primordial stage. Commercial cultivationprotocol was followed, while six uninoculated bags were used as controls.Twelve days after inoculation with SZMC 23834, the compost was almostblack without visible Agaricus mycelia, while green spots were detected bothin the compost and casing 14 days after inoculation. Fruiting bodydevelopment into mature mushrooms was inhibited in the artificially inoculatedbags. The underdeveloped fruiting bodies became covered by deep brownspots, while those developing on the uninoculated bags remained healthy. Thecompost infection by T. aggressivum f. aggressivum resulted in 100% croploss, while 50% loss in the number of the fruiting bodies was recorded whenthe casing soil was treated. The pathogen was reisolated from compost andcasing soil samples inoculated with T. aggressivum f. aggressivum. Tenrecultured isolates were confirmed as T. aggressivum f. aggressivum based onITS sequence analysis. To our knowledge, this is the first report of epidemicgreen mold outbreak in Europe due to the North American green mold biotypeT. aggressivum f. aggressivum.References:Andersson, M., et al. 2009. J. Appl. Microbiol. 106:909.Hatvani, L., et al. 2007. Phytopathology 97:532.Samuels, G. J., et al. 2002. Mycologia 94:146.e-XtraPlant Disease /nnn 2017 1There are no queries in this article.AUTHOR QUERIESPLEASE RESOLVE ALL QUERIES

First report of Trichoderma aggressivum f. aggressivum green mold on Agaricus bisporus in Europe

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First report of Trichoderma aggressivum f. aggressivum green mold on Agaricus bisporus in Europe

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