A mushroom culture of Agaricus bisporus produced by hybridization of a first strain and a second strain of Agaricus bisporus, wherein at least one of said first and second strains of Agaricus is a hybrid mushroom culture of Agaricus bisporus designated strain J9277. Diverse additional strains can be developed from J9277 by various means including somatic and tissue culture selection, basidiospore selection, and hybridization to other strains of Agaricus bisporus, and the resulting derivative strains can be screened for desirable commercial characteristics. One resultant class of the mushroom Agaricus bisporus (J. Lange) Imbach is the hybrid strain J10165. It exhibits an attractive appearance that includes a smooth, bright white cap, and is biologically incompatible with strains of the ‘U1’ lineage group. A method for improving facility hygiene and reducing disease incidence at any commercial Agaricus bisporus mushroom production facility is also provided.