MOSAIC OF SUGAR CANE AND OTHER GRASSES. 



11 



of roots and shoots at the nodes of standing cane. Figure 2 shows 

 such a condition in Yellow Caledonia cane. The photograph repro- 

 duced here was taken at Arecibo, Porto Rico, in 1919, and the 

 probabilities are that the plant had been infected for at least five 

 years. These iden- 

 tical cuttings and 

 similar ones were 

 brought to Washing- 

 ton and planted in 

 a quarantine green- 

 house. Most of them 

 grew, but at the pres- 

 ent time, five months 

 after planting, they 

 are scarcely 1 foot 

 tall. The opaque 

 white streaking 

 covers practically ah 

 of the leaf area. This 

 is the most excessive 

 injury ever observed 

 by the writer. Most 

 varieties of cane do 

 not go to pieces like 

 this, but rather the 

 injury to stalks con- 

 sists merely of re- 

 tarded development. 

 Among the well- 

 known varieties, 

 however, all grada- 

 tions in the extent of 

 injury between these 

 two extremes are to 

 be found. 



When a large pro- 

 portion of the plants 

 in a field are infested, 

 the aspect in general 

 resembles the effect 

 of a severe drought. 

 The foliage of the entire field is yellowish, and the plants are more or less 

 noticeably stunted. Where a row of some immune variety is planted 

 in or near a badly infested field, the contrast in color is exceedingly 

 conspicuous and the dwarfed habit of infected plants is more notice- 



Fig. 2.— Canker stage in Yellow Caledonia sugar cane; healthy cane of 

 the same variety in center. 



