Apr. 21 ,1923 
Cultivated and Wild Hosts of Cane Mosaic 
259 
later, the infection must come each year from some diseased perennial 
grass. In all sugar-cane plantations, com is invariably used in the crop 
rotation, and one of the required conditions for infection of com is present 
if the disease exists in the nearby cane. 
Com mosaic has now been reported from Porto Rico, the United States, 
Guam, the Hawaiian Islands, and Trinidad. 
In a publication by Kunkel (12), just received from Hawaii, a very 
complete cytological investigation of corn mosaic is recorded. Certain 
large bodies found in the cells of diseased tissues are described and sug¬ 
gested as the possible cause of the disease. Such cell inclusions have 
been noticed and recorded by early investigators of mosaic, but this 
was not mentioned and possibly was overlooked by Kunkel. Practically 
identical bodies were carefully described and accurately illustrated by 
Iwanowski (10) in his researches on tobacco mosaic published nearly 
20 years ago. The latter, however, was cautious about ascribing to 
these bodies any etiological significance merely on the basis of their asso¬ 
ciation with the disease. The paper by Kunkel referred to above con¬ 
tains some data of value on susceptibility of corn varieties to mosaic. 
His presentation of the history of our knowledge of this disease in corn 
is very misleading. One of the present writers contributed the original 
paper on com mosaic (4). This paper, which was based on careful 
observations and experiments established the type of disease, its infect 
tious nature, its identity with sugar-cane mosaic, and the natural agents 
of transmission. Within its pages ample credit was given to two pre¬ 
vious investigators for observation of a possibly similar condition in 
corn. Their observations were of a very indefinite nature and were 
summed up in the following words by the only one of the two who pub¬ 
lished on it (16): 
The trouble was ascribed to various causes by different people, but it appears to 
be the same baffling general condition observed in Hawaii rather than any specific diseased 
On the basis of this candid admission and other less reliable evidence 
Kunkel, perhaps unintentionally, leads the reader to believe that the 
disease was well known and well understood prior to the present writers’ 
contribution. 
FIELD OBSERVATIONS ON SORGHUM AND PEARL-MILLET MOSAIC 
Although mosaic on sorghum was early noted by one of the writers in 
experiments at Washington (2) and afterwards proved to be identical 
with sugar-cane mosiac (j), it was not observed in the field until the 
summer of 1920. At that time many fields of sweet sorghum were no¬ 
ticed to be naturally infected in the vicinity of Cairo, Ga. All such 
fields were within half a mile of affected sugar cane. No accurate data 
were obtained on injury to sorghum, but the leaf symptoms were strongly 
marked, the nondevelopment of chlorophyll being about the same as in 
severely injured sugar cane, and the plants were decidedly stunted. It 
was noticed that when plants were infected soon after germinating, the 
injury was far greater than in the case of late infection. A few notes 
were taken on varieties affected and on the percentage of infected plants 
in various fields. 
The variety Honey appears to be especially susceptible. Several fields 
of this variety, known locally as Sugar Drip, were observed to contain 6 
• The italics are ours. 
30617—23—6 
