CEREAL Chords * DISEASE! 
JOIMAL OP AOaqiLTDRAl RESEARCH 
Vol. XXXI Washington, D. C., July 1 , 1925 No. 1 
FURTHER STUDIES ON THE OVERWINTERING AND 
DISSEMINATION OF CUCURBIT MOSAIC 1 
By S. P. Doolittle, Pathologist, and M. N. Walker, /wmor Pathologist? Office 
of Cotton, Truck, and Forage Crop Disease Investigations , Bureau of Plant 
Industry, United States Department of Agriculture 
INTRODUCTION 
Earlier studies of the mosaic disease of cucurbits have shown that 
a knowledge of the agencies by which the disease lives over winter 
is essential to the development of efficient control measures. The 
results reported in previous papers (5, 5) 3 indicated that the soil 
was not a factor in overwintering the disease and that the seed of 
the cultivated cucumber, Cucumis sativus L., was rarely, if ever, a 
source of infection. There was also no evidence that the striped 
cucumber beetle, Diabrotica vittata Fabr., was an agency in the over¬ 
wintering of mosaic. There was evidence, however, that the disease 
might overwinter on wild host plants, since it was found that seeds 
from mosaic plants of the wild cucumber, Micrampelis lobata (Michx.) 
Greene, would produce a certain percentage of mosaic diseased seed¬ 
lings ( 7 ). Continued investigations during the past three years have 
shown that cucumber mosaic is transmissible to a number of plants 
of other families and have established the importance of certain wild 
host plants in the overwintering of the disease. 
It is the purpose of this paper to present the evidence obtained from 
numerous experiments which have led to these conclusions. 
SOIL IN RELATION TO OVERWINTERING 
Experiments in Wisconsin and Michigan, prior to 1919 (8), indi¬ 
cated that cucurbit mosaic was not carried in the soil, and the results 
of further trials during 1919 and 1920 have strengthened this con¬ 
clusion. All of these later experiments were conducted at Madison, 
Wis., on the same land as that used in the trials of 1917. This plat 
had grown cucumbers for three successive years, and the mosaic 
disease had been severe there each season. 
EXPERIMENTS OF 1919 
The plat was planted to cucumbers on June 19, using commercial 
seed of the Chicago Pickling variety. Ten cheesecloth cages of the 
1 Received for publication August 20,1924; issued September, 1925. 
2 The writers are indebted to W. W. Gilbert, of the Office of Cotton, Truck, and Forage Crop Disease 
Investigations, for valuable suggestions and advice during the progress of this work and for assistance in 
obtaining certain field data and material used in these studies. They are also indebted to L. R. Jones, of 
the Department of Plant Pathology of the University of Wisconsin, for advice and criticism during the 
course of this work. 
The Department of Plant Pathology, University of Wisconsin, has cooperated in furnishing land and 
laboratory and greenhouse facilities necessary for these investigations, and certain interested pickle 
companies and growers have cooperated by furnishing funds and facilities for carrying on the work on 
eradication and control in the field. 
3 Reference is made by number ( italic ) to “Literature cited,” p. 57. 
Journal of Agricultural Research, Vol. XXXI, No. 1 
Washington, D. C. July 1,1925 
Key No. G-489 
59836—25t-1 
(i) 
CEREAL INVESTIGATIONS. 
