BUREAU OF PLANT INDUSTRY. 177 



edge of the inferior fiber produced by these plants, which were sup- 

 i:)osed to be abaca, this infoiTnation has an important bearing on 

 future experimental work with abaca. 



SUGAR CANE. 



Sugar-cane mosaic attacks sorghum, corn, several species of wild 

 grasses, and probably other plants. It has been transmitted from 

 plant to plant by artificial means and also by the corn aphis in the 

 sugar-cane greenhouse of the bureau. The mosaic does not remain in 

 the soil and hence may be eliminated from a field by careful and 

 thorough roguing, provided all other hosts are likewise destroyed. 



A plant diseased with sugar-cane mosaic does not recover; hence 

 the disease will remain and be a possible source of infection as long 

 as the plant is alive. The destruction of diseased plants and the 

 use of healtliy seed cane are the only known methods by which 

 sugar-cane mosaic may be eliminated. 



Mosaic lias been found in each of our cane States, and ever}^ field 

 has been insi^ected and the degree of infection, if any, has been de- 

 termined and recorded. Some of the States are cooperating in the 

 control of the mosaic in the cane areas. •• The disease has been re- 

 duced practically to the point of elimination in parts of Porto Rico 

 and in the eastern and peninsula part of Florida, where the roguing 

 advocated by the bureau has been practiced according to directions. 

 The immune variety of cane, Kavangire, imported by the bureau 

 from Argentina in 1919, is being rather generally planted and in 

 badh' diseased areas promises to displace the susceptible varieties. 



FRUITS. 



CITRUS FRUITS. 



Grapefimit Hjyening and storage. — Because of the fact that the 

 great bulk of the grapefruit crop is marketed during a comparatively 

 short period and because of certain serious difficulties which have 

 been experienced in holding this fruit in cold storage, considerable 

 work has been done in an effort to determine satisfactory methods 

 of handling the fruit and to learn the limits of storage. Successful 

 storage obviously has large possibilities, in view of the fact that 

 by holding the fruit in cold storage for a considerable length 

 of time the marketing period would be extended, thereby making 

 grapefruit available to the consumer over a longer period and at the 

 same time tending to eliminate gluts in the market which are likely 

 to result from the present necessity of disposing of the crop in a 

 limited time. 



The results of the work have been very promising. The procedure 

 has been to procure fruit from individual trees at different times 

 and to handle comparable lots differently, both during the prestorage 

 period and while in storage. Chemical analyses of the fruit have 

 been made from time to time in order to determine the biochemical 

 effect of different methods of handling and storing, as well as for 

 the purpose of gaining information in regard to the biochemical 

 processes that go on in different fruits from the time they are har- 



