20 BULLETIN 828, TJ. S. DEPARTMENT OF AGRICULTURE. 
There is a tendency for wilt to spread in groups around the plants 
first developing the disease, and in all observed cases it always starts 
from beetle-injured plants. The facts that a careful record was kept 
of all cucurbits in these localities and that the first wilt to appear 
was from beetle injuries on the earliest plantings of the season pre- 
clude the possibility of a transfer of the disease from previously 
wilted cucurbits of the current season. These results, added to the 
data presented in our previous papers, negative the possibility of 
transmission of bacterial wilt of cucurbits through the soil from 
season to season and give strong circumstantial evidence in favor of 
the cucumber beetles as winter carriers. 
Until the striped or 12-spotted cucumber beetles can be hiber- 
nated successfully in considerable numbers and under experimental 
conditions, absolute experimental proof that these insects are winter 
carriers can not be obtained. However, it would appear from the 
evidence given that either the beetles must have carried the wilt 
organism over winter or must have brought it directly from previous 
cases of the current season. The second assumption is eliminated 
so far as cucurbits are concerned by the facts that in neither locality 
were cucurbits grown under glass, that our observations covered a 
considerable territory, and that the wilt appeared on the very earliest 
plantings of the season only after the plants were bitten by the 
beetles. In one locality no wild cucurbits were present within at 
least 10 miles. 
Apparently the only loophole remaining is the possibility that the 
organism may live over winter in some perennial noncucurbitaceous 
host. In his early work upon this organism, Dr. Erwin F. Smith 
obtained infections by pure-culture inoculations on various species 
of Cucumis and Cucurbita and on Benincasa cerifera, Sicyos angulatus, 
and ' lEcrampelis lohata, and failed to infect or obtained only local 
injury on the following cucurbits: Mdothria scabra, Cucumis erina- 
ceus, Luffa acutangula, Momordica balsamina, Lagenaria vulgaris, 
TrichosantTies cucumeroides, and Apodanthera undulata. 1 He states 
further: 
"Inoculations into noncucurbitaceous plants such as Solanum tuberosum, Lyco- 
persicum esculentum, Datura stramonium, Passifiora incarnata, Vigna catjang, Xico- 
tiana tabacum, Pyrus orientalis, and Hyacinihus orientalis yielded only negative 
results. The disease is not known to occur outside the Cucurbitaceae, and probably 
many species of plants within the l imit s of this family are not subject to it. " 
The present writers have no data concerning the possible occur- 
rence of this disease outside the Cucurbitacese. 
i Smith, Erwin F. Bacteria in relation to plant diseases, v. 2, p. 209. Washington, D. C, 1911. 
(Carnegie Inst., Washington. Tub. 27, v. 2.) 
