BUREAU OF PLANT INDUSTRY. 183 



the results of several years' work in these sections will be made avail- 

 able a year or two hence for the benefit of the growers. 



In a series of cropping; tests data of importance have been secured 

 as to the relationsliip of tobacco to other croi)s grown in rotation 

 with respect to the quality of the tobacco produced as well as the 

 yield of tobacco and the other crops. These data will be of great 

 value in arriving at a correct estimate of the proper position of 

 tobacco in the farming system. In this work it has been found 

 that the action of fertilizers on the tobacco crop is greatly influenced 

 by the other crops in the rotation, and the character or extent of 

 these influences could not be predicted from previous knowledge of 

 the subject. 



It is believed that the problem of securing an adequate supply 

 of seed of the Maryland Mammoth tobacco has been solved through 

 the discovery that seeds are readily produced when the plant is 

 exposed to the action of a reduced length of day during its develop- 

 ment, such as prevails in southern Florida during the winter months. 

 This variety of tobacco is very popular among Maryland growers, 

 but hitherto it has not been possible to secure seed in quantity, since 

 the plant is normally sterile when grown in northern latitudes. In 

 the so-called " old belt " of the flue-cured tobacco district the method 

 of harvesting by picking the leaves from the stalk instead of cutting 

 the stalk at its l)ase. with the acrompan3'ing feature of high top- 

 ping, which Avas recently introduced by the bureau, is rapidly coming 

 into general use. It is estimated that in Granville County, N. C, 

 where the method was first introduced, fully 90 per cent of this 

 year's crop will be thus harvested, adding from $1,000,000 to $2,000,- 

 000 to the value of the tobacco crop of the county. 



NEW CROP PLANTS AND CROP EXTENSION. 



BINDER-TWINE FIBERS. 



Work begun in 1917 in cooperation with the Philippine Bureau 

 of Agriculture has been continued. The introduction of three fil)er- 

 cleaninp; machines by the two Governments, for the purpose of dem- 

 onstrating the efficiency of machines as compared with water-retting 

 and hand-cleaning methods used heretofore in the Philippines in 

 the preparation of Manila maguej'^ and sisal, has resulted already 

 in the purchase by private capital of 12 other machines. These 

 large machines, having a capacity of 1 to 2^. tons of clean dry fiber 

 per day, are being built in this country and forwarded and installed 

 as rapidly as possible. This will change the industry within a 

 short time from hand-cleaning to a machine-cleaning basis, pro- 

 ducing fiber of much better quality and with possibilities of much 

 greater quantity. 



A half million sisal plants have been introduced from Hawaii, 

 and nurseries are being established in the Philippines to insure a 

 future supply for planting. The Philippine Government has as- 

 signed a man to encourage the industry, and improvements are being 

 made in the metliods of planting and taking care of the plantations. 



The production of Manila maguey and sisal in the Philippines, 

 amounting to more than 9,000 tons during the first five months of 

 1920, was approximately equivalent to 20 per cent of the total pro- 



