CONTROL OF CUCUMBER MOSAIC 11 
weeds were abundant, however, and in many cases were found to 
occur in and about the seed beds. Field observations indicated that 
the infection in the field could be traced to this source, and eradica- 
tion experiments were conducted on six farms in 1923 through the 
cooperation of L. S. Foote, the local county agent. Mosaic had been 
severe in all these fields during the preceding season and in earlier 
years. At the end of the season of 1923, late in July, four of the 
six fields showed losses of only 10 to 20 per cent from mosaic as 
against an average loss of 60 per cent in 1922. In the two remain- 
ing fields the eradication work had been abandoned by the growers 
early in the season, and both showed losses of from 40 to 50 per 
cent from mosaic, as did other fields in the immediate vicinity. 
These experiments, though only of a preliminary nature, indicated 
that in sections where the pokeweed occurs its eradication may result 
in a considerable reduction in the amount of mosaic in the field. 
RECOMMENDATIONS FOR MOSAIC CONTROL 
The experiments at Madison have demonstrated that mosaic can 
be controlled in an isolated field by the removal of the wild 
host plants, and the work at Rockland has further shown that this 
method of control may greatly reduce the loss from mosaic when 
applied to larger areas. The Rockland section has presented a more 
severe test of such control measures than is found in most cucumber - 
growing districts, since the fields were grouped closely in and about 
the town, all of them being within a radius of half a mile. Such 
an arrangement presented the difficulty that a single infected field 
might act as a source of infection to several others, and to control 
the disease, therefore, it was essential that most of the fields remain 
practically free from mosaic until late in the season. Mosaic host 
plants were abundant, as they are usually more numerous about 
towns where there are many gardens, and their eradication, there- 
fore, was more difficult than it would have been in the case of fields 
more widely scattered over the surrounding country. In addition 
to this, no attempts were made to control either the aphis or the 
striped beetle, although such measures might have simplified the 
problem to a considerable extent. In several cases, also, cucumbers 
were persistently planted on land infested with mosaic milkweeds, 
thus furnishing a possible source of infection for other fields. In 
view of the results obtained under such conditions it is believed that 
the control of the disease is a practical possibility in most sections 
if the following practice is adopted. 
Cucumbers should not be planted continuously on the same land. 
The rotation of the cucumber crop is advisable for the control of 
other diseases, such as anthracnose and scab. In the case of mosiac 
it is necessary to remove the crop from a location where the gradual 
accumulation of a reservoir of infection in perennial weed hosts 
affected with mosaic would serve as a source of infection during 
following seasons. 
The cucumber field should be located at a distance from the farm 
buildings and vegetable garden. Such isolation is important because 
it has been found that the wild cucumber, milkweed, and ground 
cherry are commonly found about farm buildings and that mosaic 
