136 



Journal of Agricultural Research 



Vol. XIX, No. 3 



Experiment 7. — On November 20, 1919, two mosaic cane plants of the 

 Rayada variety, infested with the sugar-cane mealy bug {Pseudococcus 

 honinensis (Kuw.),^ vvere placed in each of two cages, together with two 

 healthy cane plants of the Lahaina variety. A few of the mealy bugs 

 were transferred from diseased plants to all healthy plants. Ants were 

 assiduously tending the mealy bugs. On March 11, 1920, all healthy 

 plants were badly infested with mealy bugs but there was no mosaic 

 infection. 



ARTIFICIAI, INOCULATIONS 



Virus was obtained for artificial inoculation by two methods. Cell sap 

 from young leaves, designated as virus No. i, was obtained by grinding 

 the young, tightly rolled leaves of diseased Rayada cane in a food chopper 

 and straining through several thicknesses of cheesecloth. It was used 

 undiluted for inoculating immediately after being prepared. Virus No. 2 

 consisted of cane juice from the youngest joints, including the growing 

 point. To prevent oxidation this was pressed out under a mineral oil 

 (Nujol) in a specially designed press (2). This also was used undiluted 

 as soon as it was prepared. Inoculations were made in the compartment 

 of the fumigated greenhouse separated from all diseased material and 

 protected by every means from accidental infection. The results of these 

 inoculations are given in Tables I and II. 



In addition to the control plants injured with a sterile needle, there 

 were about 100 other healthy plants of the Lahaina variety in the com- 

 partment. No case of mosaic developed among these plants. 



Table I. — Effect of artificial inoculation of Lahaina cane with triturated young leaves 



{virus No. l) 



[Plants inoculated Jan. 8, 1920] 



' Identified by Mr. Harold Morrison, of the Bureau of Entomology, United States Department of Agri- 

 culture. 



