February, ’24] Glasgow & gloyer: mercuric treatment for cabbage 
95 
THE MERCURIC CHLORIDE TREATMENT FOR CABBAGE 
MAGGOT CONTROL IN ITS RELATION TO THE DEVELOP¬ 
MENT OF SEED-BED DISEASES 
By Hugh Glasgow and W. O. Gloyer, Geneva , N. Y. 
Abstract 
Rhizoctonia and some of the other common diseases of cabbage seed-beds are 
held in check by applications of mercuric-chloride solution as used in the control of 
the cabbage maggot, Chortophila brassicae Bouche. 
The other two methods in common use for maggot control,—the cheesecloth 
screen and applications of tobacco dust,—appear to favor the development of such 
fungous troubles, especially during wet seasons. 
Applications of mercuric chloride which give the most satisfactory control of the 
root maggot also appear best adapted to the control of the diseases studied. One 
very early application followed by one or two later applications at intervals of a week 
or ten days gave the best results. 
Cabbage as grown commercially is subject to a number of serious 
diseases, some of which originate and are propagated in the seed-bed, 
and from here may be transferred to the field at the time of transplant¬ 
ing. Some of these diseases, while they have no direct connection with 
the work of the cabbage maggot, are nevertheless of interest in this con¬ 
nection since methods that have been advocated for the control of the 
maggot may, under certain conditions, have a profound influence on 
their development and dissemination. 
Screening, for example, is perhaps the most efficient and without 
doubt the most generally accepted method for the protection of cabbage 
seed-beds from maggot attack. The cheesecloth screen serves admirably 
for this end, affording a great measure of protection from certain other 
insect pests as well as stimulating the plants to a more rapid growth. 
However, it has the weakness of increasing the liability to loss from 
certain pathogenic, soil-inhabiting fungi whose development and spread 
may be favored by the slightly higher temperatures and greater hu¬ 
midity found beneath such a screen. 
Applications of tobacco dust also show a high degree of efficiency in 
preventing maggot injury as well as possessing other distinct advantages. 
Here, too, the development of these fungi appears to be favored, so that 
where outbreaks of such diseases are anticipated the use of tobacco dust 
in the seed-bed might well be of questionable value. 
In our work with the cabbage maggot it has been observed for the 
past three or four years that the seedlings in different plats under treat¬ 
ment for maggot control showed a marked difference in susceptibility to 
certain common seed-bed diseases. Some of the treatments used, 
