Apr. 9 T, X933 
Cultivated and Wild Hosts of Cane Mosaic 
255 
A, maidis has been reported on sugar cane, however, (5, 8 , iSy, and on 
other crops from many sugar-cane regions. 
While it is usually difficult to establish Aphis maidis on sugar cane in the 
greenhouse by transplanting them from other grasses, they sometimes 
migrate naturally to the cane and are found on it in large numbers. One 
of the worst infestations of any grass by A. maidis ever seen by the 
writers was on sugar-cane seedlings about 5 months old. It was brought 
to our attention by Dr. B. T. Galloway, who was growing the seedlings 
in one of the Washington greenhouses. In some of our experiments where 
A. maidis failed to become established and disappeared within 2 or 3 
days, the plants nevertheless were infected by them and showed symptoms 
after the usual incubation period of 14 to 20 days. Corn, sorghum, and 
pearl millet are favorite food plants for A, maidis^ which is frequently 
found on them in enormous numbers. The insect is an ideal carrier in the 
case of these three crops. Several species of leafhoppers have been held 
under suspicion as vectors of grass mosaic on account of strong indirect 
evidence, but no positive proof of such capacity on their part was devel¬ 
oped. 
SOME ECONOMIC ASPECTS OF GRASS MOSAIC 
TESTS with cane varieties OF THE NORTH INDIA TYPE 
Practically all of the well-known varieties of sugar cane are susceptible 
to grass mosaic. Prof. F. S. Earle noticed, however, that the so-called 
Kavangire, a variety of the slender North India type, was not affected 
under conditions favorable to the transmission of the disease (15). 
Later observations have indicated that the Uba, grovm extensively 
in Natal, and Cayana No. 10, in the sirup sections of this country, are 
apparently immune. These varieties are of the same type, and Prof. 
Earle has declared that Kavangire is identical with the old well-known 
Uba (6). A collection of varieties of this type from various parts of 
the world was brought together in Washington to determine whether 
immunity to mosaic is characteristic of the whole group. They were 
placed in a greenhouse exposed to natural infection, with the results 
indicated in Table IV. 
Table IV .—Susceptibility to the mosaic disease of the varieties of the North India type of 
sugar cane 
Variety. 
Date exposed. 
Result. 
Date examined. 
Condition. 
Uba. 
Jan. 6,1921 
.do. 
July I,1921 
All healthy. 
TTsivfiTioi’irf* .. 
Do. 
Onvarifl Mn to . 
.do. 
.do. 
Do. 
Saccharum narenga (S.P.I. No. 
38332)- 
TTVi^ira D T Mo ' 3‘7 0 ao\ . 
.do. 
.do. 
Jan. 25,1921 
.do. 
All mosaic. 
Do. 
P T. No. 'I'l'iA'i) . 
July 1,1921 
.do. 
All healthy. 
TiTinar ( 9 ^ P T No 2 2'2/ie). 
Do. 
Obikitsho (S P I. Nr> 9 oto6). 
Jan. 25,1921 
All mosaic. 
Var from ICap’awa Rpri (S-P-I- 
Do. 
No. 29107). 
( 5 % P I No 20108) 
Do. 
Osbiina (S P.I. No. 20100)... 
July 1,1921 
Jan. 25.1921 
All healthy. 
Oliilciiolia (S P T No. . r - - 
.do. 
All mosaic. 
« Mr. A. C. Baker reports A phis maidis on sugar cane in the quarantine greenhouse of the Feder^ Horti¬ 
cultural Board at Washington, March ii, 1920 (in letter to the writers, December 2, 1921), and Mr, Geo. W. 
Wolcott reports finding this species on sugar cane in Porto Rico (in letter to Dr. C. O. Townsend, December 
30, 1921). 
