16 



MUSHEOOM GROWING IN THE UNITED STATES 3 



in the growth of the mushroom plant, namely, the germination of 

 the spores, the development of the mycelium underground, and the 

 growth of the fruiting body or mushroom above the ground. 



DEVELOPMENT OF THE INDUSTRY 



The practice of cultivating the common mushroom originated in 

 France in the latter part of the seventeenth century, but it was 

 not until toward the end of the nineteenth century that it began to 

 gain a foothold in the United States. At first mushrooms were 

 grown as a side line to market gardening, but as the market devel- 

 oped specialization began. 



Although at first abandoned limestone quarries, mines, and sand- 

 stone caves were used, the structure that eventually found most 

 favor in this country was the specially constructed mushroom house 

 filled with tiers of shelf beds. On the average, better crops are 

 obtained in these houses than in caves, because favorable conditions 









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Figure 3. — Map showing (by dots) the approximate distribution of the mushroom 

 industry in the United States 



can be more readily obtained and diseases and insect pests are more 

 easily controlled. 



As a result of the widespread use of these special houses and the 

 development of better methods of making spawn, the industry has 

 made rapid strides in the last 30 years and at present 15,000,000 

 to 20,000,000 pounds of mushrooms are produced annually. About 

 three-fourths of the industry is located in eastern Pennsylvania 

 and northern Delaware, near the ready markets for mushrooms 

 and supplies of manure in New York City and Philadelphia, but 

 there are also important centers in other States. (Fig. 3.) 



SPAWN 



Since the beginning of mushroom culture growers have planted 

 their beds with a specially prepared material filled with living mush- 



