104 



LETTUCE. 



house dry and warm for three days, but most people do 

 not discover it soon enough. Fungicides I do not use, 

 but generally, when necessary, smoke the house, or place 

 powdered sulphur on the steam pipes. For smoking, to- 

 bacco stems are used. When lettuces grow ' dog-eared ' 

 it is the fault of the grower ; he has kept the temperature 

 too high." 



Varieties. There are two general types of forced let- 

 tuce, the cabbage or heading type, and the loose or leafy 

 type. The former is chiefly desired in the easternmost 

 markets, but is little sought west of New York state. It 

 is more difficult to grow than the loose varieties, being 

 more particular as to soil and treatment, and requiring a 

 somewhat longer season. It is grown to perfection only 

 on loose soils and in solid ground beds. The varieties of 

 the White-Seeded Tennis Ball or Boston Market type are 

 most popular for heading lettuces. The accompanying 

 illustration (Fig. 34, page 103) shows four heads of Bos- 

 ton Market lettuce sent me by W. W. Rawson, Arlington, 

 Mass. The head on top weighed, with roots cut off, 7 

 ozs., and the one at the left 9^ ozs. The Grand Rapids 

 is a loose-leaved lettuce, shown full grown in Figs. 32 

 a "d 33 (pages 95 and 98). It grows rapidly, is of very 

 easy cultivation, and is at the present time the most 

 popular lettuce, except in those particular localities where 

 the heading varieties are preferred.* 



Enemies and diseases. The most inveterate pest of 

 the lettuce grower is the green-fly or aphis. If it once 

 gets thoroughly established, the most strenuous efforts are 

 needed to dislodge it. The pest is most frequent in 

 houses that are kept too warm. The plants may be 

 sprinkled with tobacco dust, or tobacco stems may be 

 strewn upon the ground between the plants and in the 

 walks, and either treatment may be expected to keep 



*A test of the varieties of lettuce for forcing purposes is recorded 

 in Bull. 43 (1892) of the Ohio Exp. Sta. 



