February, ’23] 
GLASGOW: CABBAGE MAGGOT IN SEED-BEDS 
71 
will be discussed in detail at this time, since the results are fairly typical 
of all the experiments. None of the other materials tested, with the 
exception of tobacco dust, gave any great promise of success. 
In order to secure data bearing on the problem from as many angles 
as possible, such as the proper time to commence treatment, the number 
of applications necessary to secure satisfactory control and the actual 
benefit to be derived from deferred applications made to beds already 
infested by the maggot, the following scheme was carried out for each 
material in all the detailed tests that were made, namely, for each ma¬ 
terial or concentration to be tested a block of twenty-one continuous 
rows was selected, such a block being divided into plats of six, five, four, 
three, two and one row respectively, as indicated on page 70. 
Of the six applications to be put on at weekly intervals, the first was 
made from four days to one week after the plants had commenced to 
appear above the ground and included all six rows of Plat 1. The second 
application included the first and second Plats except that Row 1 was 
omitted from Plat 1. In the case of the third application Plats 1, 2 
and 3 were treated with the exception of Rows 1 and 2 of Plat 1 and 
Row 1 of Plat 2, which were omitted. This process was repeated at 
intervals of approximately one week until all six applications were made, 
one new plat in this way being added and one row successively dropped 
from each of the preceding plats at each application. At the end of 
this six-weeks’ period we therefore have twenty-one different combi¬ 
nations bearing on the time and frequency with which each of the 
materials tested may be applied. 
The accompanying tables summarize the results of such a test carried 
on in the same cabbage seed-bed during two successive seasons,—1921 
and 1922. In this case the material tested was mercuric chloride di¬ 
luted at the rate of approximately 1-1200 or 1 ounce to 10 gallons of 
water. The solution was applied with a watering pot from which the 
rose sprinkler had been removed so that the liquid could be directed 
along the row^s in a solid stream. The applications were made at the 
average rate of about 1 gallon to 30 feet, more of the solution being re¬ 
quired for the late application than where the plants were young. 
During 1921 the infestation, while bad, was not as severe as in some 
seasons, while in the year following it was much less general, the 
unprotected plats in 1921 showing an average infestation of 73 percent 
as against 43 percent for 1922. 
As may be seen from the results of these tests summarized in Tables 
1 and 2, perfect control was secured in 1922 by two early applications. 
