FIRST REPORT OF PHYSARUM COMPRESSUM IN BLACK POPLAR MUSHROOM CROPS IN SPAIN
F.J. Gea, M.J. Navarro
The commercial cultivation of black poplar mushrooms (Agrocybe aegerita) in Spain is a recent activity, which is carried out in hygienic and climatologically controlled conditions using mainly pasteurised wheat straw substrates. In 2008 the presence of a myxomycete was detected during cropping in several black poplar mushroom crops in Castilla-La Mancha (Spain). Both plasmodium and sporocarps were found on the substrate, on the plastic substrate packing and on the A. aegerita sporophores. The myxomycete was identified as Physarum compressum according to current taxonomic criteria (López and García, 2002; Desrumaux et al., 2003). The growth of this slime mould affects the colour of the caps of A. aegerita carpophores, which turn light brown/ beige, lowering their quality to such an extent that the mush- rooms become unmarketable. The inoculation of plasmodium and spores to healthy A. aegerita fruiting bodies resulted in no plasmodium development or colour loss in the caps. Two crop cycles involving 100 blocks of substrate per cycle, were moni- tored, from the incubation phase to the end of harvesting in or- der to assess the presence of the myxomycete, which was found in 12 and 65, respectively, of the cultivated blocks. P. compressum has previously been described in intensive Pleurotus cultures that use pasteurised substrates similar to those employed for cultivat- ing A. aegerita (Desrumaux et al., 2003). To the best of our knowledge, this is the first report of P. compressum in black poplar mushroom farms in Spain.