44 
Journal of Agricultural Research 
Vol. XXXI, No. 1 
Gourds ( Cucurbita pepo var. ovifera): Dipper, Egg, Orange, Pear, Turk’s Turban. 
Gourds (Lagenaria vulgaris): Bottle, Calabash, Hercules Club, Spoon, Sugar 
Trough. 
Gourds (Luffa cylindrica): Dish Cloth, Sponge. 
Citron ( Citrullus vulgaris): Green-seeded citron. 
The following varieties of watermelon and citron (Citrullus vul¬ 
garis) have been found to be apparently immune to cucurbit mosaic: 
Watermelon: Halbert Honey, Kleckley Sweet, Mammoth Santiago, Olds 1908, 
Tom Watson, Sweet Heart. 
Citron: Red-seeded citron. 
From 8 to 50 inoculations have been made with each variety, using 
both insects and artificial methods of inoculation. A considerable 
number of cross inoculations have also been made between the various 
species found to be susceptible to the disease. All but one variety 
of those tested in the genus Citrullus seemed to be nonsusceptible 
to the disease. As far as the writers are aware, no evidence of mosaic 
infection has ever been obtained on watermelons inoculated either 
by means of aphids or by artificial methods, although many varieties 
from many parts of the world have been used in these experiments. 
Since both Allard ( 1 ) and Nishimura (17) have presented evidence 
which tends to show that certain species of the Solanaceae may carry 
the infective principle of mosaic without showing visible symptoms, 
a number of inoculations were made to both cucumber and musk- 
melon from watermelons which had been inoculated with cucurbit 
mosaic. ' These inoculations were made both by artificial methods 
and by aphids, chiefly the latter, but no evidence was obtained which 
would indicate that the watermelon may carry the disease without 
the appearance of visible symptoms. 
CROSS INOCULATIONS FROM THE CUCUMBER TO PLANTS OF OTHER FAMILIES 
Experiments with Martynia 
The susceptibility of the martynia (Martynia louisiana) to cucurbit 
mosaic has been briefly noted in an earlier paper (8). Although 
earlier inoculations indicated that the disease could not be trans¬ 
mitted to this host, it was later found that the martynia could be 
readily infected with mosaic when aphids were used as a means of 
inoculation (pi. 5, A, B). A continuation of these experiments has 
given definite evidence of the susceptibility of the martynia to cucur¬ 
bit mosaic. Further experiments nave also shown that the disease 
may be transmitted from the cucumber to the martynia by artificial 
inoculations as well as by aphids. The results of these inoculations 
are given in Table XVII. 
The susceptibility of the martynia to cucurbit mosaic under field 
conditions has been demonstrated by experiments in which martynia 
plants were grown between rows of cucumbers in the field. The 
cucumbers developed mosaic early in the season, and a number of 
the martynias also became infected with the disease after its appear¬ 
ance on the cucumber. Inoculations from these plants to healthy 
cucumbers resulted in a high percentage of infection. The suscep¬ 
tibility of the cucumber to the mosaic disease found on the martynia 
has also been proved by inoculations from martynia plants inoculated 
from mosaic cucumbers as well as from those found naturally infected 
in the field. As shown in Table XVIII, the disease is transmissible 
from the martynia to the cucumber by either method of inoculation. 
