228 



CASSAVA 



CASSAVA 



equal variations, but either of these characters 

 may change in the first generation when plants 

 are grown from seeds. The roots of all varieties 

 contain some hydrocyanic (prussic) acid, the 



Fig. 323. Cassava roots. 



quantity varying from a mere trace in some of the 

 sweet varieties to as much as .03 per cent in 

 some of the so-called "bitter" sorts; but the quan- 

 tity in any variety, even when grown from cut- 

 tings, varies greatly with seasons, soils and 

 climates. So far as is known, all varieties grown 

 in the United States contain so little of the acid 

 as to be harmless, and the same is said to be true 

 of the sorts grown in India. The most poisonous 

 varieties often cause death a few minutes after 

 being eaten raw, but become perfectly harmless 

 when cooked or dried, and even when pulped and 

 exposed a few hours to the heat of the sun. 



History. 



Cassava was in common use in tropical America 

 when the country was first explored by the 

 Spaniards, and was introduced into western Africa 

 in the sixteenth century, and into southern Asia 

 a little later." There is no record of its introduc- 

 tion into the United States, but it was abundant 

 in Florida as early as 1860, and was in common 

 use there during the civil war as a source of starch. 

 It gradually came into use for the feeding of live- 

 stock, and, between 1895 and 1900, establishments 

 for the manufacture of starch on a commercial 

 basis were opened in that state. The area of its 

 cultivation for feeding purposes has been extended 

 gradually westward, and it is now becoming com- 

 mon as far west as Texas. 



Cultwre. 



The plant requires a light, sandy and fairly 

 fertile soil for its best success. While it produces 

 abundantly on heavy soils, the digging of the roots 

 is too expensive for profit. Some varieties make a 

 vigorous growth where the annual rainfall does 

 not exceed twenty inches, while others endure 

 as much as 200 inches without injury. Some 

 varieties mature within six months from planting, 



while others require two years before they are 

 ready for gathering. The sweet varieties are 

 usually more hardy, mature more quickly and 

 yield less abundantly than the bitter sorts. 



Propagation. — It is usually propagated by cut- 

 tings made from the stems, although a few of the 

 early-maturing varieties may be propagated by 

 seeds. In tropical countries these cuttings may be 

 made at any time, but in temperate regions con- 

 siderable care is needed to preserve the seed-canes 

 through the winter. Late in the fall, just before 

 frost, the matured canes are cut above the surface 

 of the ground, the immature tops are removed and 

 the canes are buried in windrows, much as sugar- 

 cane is preserved. Early in the spring, about 

 corn-planting time, these seed-canes are cut into 

 pieces four to six inches in length and 

 planted in checks about four feet apart. 

 The cultivation of the crop is similar to 

 that given to com. 



Harvesting. — ^The roots are ready for use as 

 early as October, but may be left in the ground 

 until the following March. As they begin to decay 

 only a few days after being disturbed, it is the 

 common practice to dig them only as they are 

 wanted for use. Under ordinary conditions in the 

 United States, the yield of merchantable roots 

 is about six tons per acre, though yields of ten 

 to twenty tons are often secured. In more trop- 

 ical regions much heavier yields are common. 



Average roots, grown in the United States, con- 

 tain 25 to 30 per cent of starch, about 80 percent 

 of which is secured in the process of manufacture. 

 The factory residue, containing about 25 per cent 

 of starch, is in good demand for the feeding of 

 horses and cattle, being valued about with com 

 meal. The roots, either boiled or roasted, form 

 a staple article of human food in all tropical 

 countries. 



Lileratv/re. 



n further information is desired, the reader 

 should consult the following: Fanners' Bulletin 



Fig. 324. A field of cassava in Florida. 



No. 167, United States Department of Agriculture; 

 Sweet Cassava, Bulletin No. 44, Division of Chem- 

 istry, United States Department of Agriculture; 

 Manufacture of Starch from Potatoes and Cassava, 



