BACTERIAL WILT OF CUCURBITS. 
39 
effective were made July 6 and 13 , respectively, and it thus seems 
apparent that the greater portion of wilt infections took place during 
the first half of July. Reference to the beetle and wilt curves for 
this field (fig. 3) shows that this was during the period when the 
striped cucumber beetles were becoming less prevalent; but when 
it is known that wilt usually appears within less than two weeks 
after inoculation it is seen that this period of greatest probable infec- 
tion corresponds with the curves showing the actual appearance of 
wilt (fig. 3, II and II a) in these two contiguous spray and cage-test 
blocks. 
During the following season (1917) another spray test was carried 
out near Tuxedo, Md., using Arlington White Spine cucumbers. 
The purpose of this experiment was to compare different strengths 
of Bordeaux mixture, as well as to gain further general evidence along 
the line of control. Applications of each mixture were made on 
June 13, 18, 25, July 2, 9, 17, 23, 30, and August 6, making nine 
treatments in all. Reference to Table II will show the different 
mixtures used and the numbers and percentages of wilted plants in 
the different plats. Two pounds of lead arsenate paste were added 
to each 50 gallons of Bordeaux mixture used. The total number of 
plants in each plat is based on the assumption of three to a hill, 
since they were thinned to approximately this number early in the 
season. Wilt in this field was not quite as serious as in the Long 
Island locality. 
Table .II. — Spray experiment at Tuxedo, Md. 
Plat 
No. 
Treatment. 
Number 
of plants 
at the 
start. 
Number 
of cases 
of wilt. 
Percent- 
age of 
wilted 
plants. 
I 
II 
in 
iv 
v 
VI 
VII 
Bordeaux mixture plus lead arsenate, 2-3-50-2 . 
Control, unsprayed 
Bordeaux mixture plus lead arsenate, 3-4-50-2 
Bordeaux mixture plus lead arsenate, 4-5-50-2. . 
Control, unsprayed 
Bordeaux mixture plus lead arsenate, 4-2-50-2. . 
Control, unsprayed 
225 
225 
225 
225 
225 
177 
16.4 
41.7 
15.5 
11.5 
35.5 
2.8 
The percentage of cases in the three unsprayed plats varied from 
30 to 42 per cent, while in the four sprayed plats only 3 to 16 per 
cent of the plants wilted. The fungicide was progressively more 
effective as the amount of copper sulphate was increased, the 4-2-50 
formula reducing the wilt to about 3 per cent. However, the excess 
of copper sulphate in this last mixture seriously burned the foliage, 
so that its general use can not be recommended. The 4-5-50 Bor- 
deaux mixture with 2 pounds of lead arsenate paste gives the best 
control of any treatment we have thus far used in our experiments. 
