THE BLACKHEAD FIKEWORM OF CRANBERRY. 
23 
gallons per acre, might be just as effective as the same kind of a solu- 
tion in which the nicotine was used at the rate of 1 part to 800 parts 
of water and applied at the rate of about 200 to 250 gallons per acre. 
The miscellaneous spraying experiments conducted on this bog in 
1919 were therefore planned in the light of the results of the pre- 
vious season. 
Time axd Number of Applications. 
The odd-numbered plats, I to XV inclusive, received 3 applica- 
tions on the dates shown in Table 3. The first application (May 13 
and 14) was made to catch the largest possible number of small larvae 
in and near the tips of the uprights before they had a chance to web 
up the new unfolding leaves. The new growth at this time was ap- 
proximately three-fourths of an inch long. The second application, 
June 12, was made to kill the next lot of larvae hatching after the first 
application and came about the time when the majority of the blos- 
soms were in the " hook stage/ 1 In order to catch the late-hatching 
larvae the third spraying was made July 1 and 2 as the vines were ap- 
proaching full bloom. The even-numbered plats, from II to XVI 
inclusive, and plat XVII, received in addition to these applications 
just described one more application (July 16 and IT) about the time 
the moths were flying on this bog in greatest abundance. The pur- 
pose of this fourth application was to kill these moths and also any 
larvae which had moved into the tips at this time. 
TVhile the frosts of May 4, 5, and 6 somewhat reduced the crop on 
nearly all the plats, the comparative results, as obtained by the ex- 
amination of the berries from 3 circular areas of about 100 square 
inches, each picked at random over each of the plats, strengthen the 
observations made of these plats at various times throughout the 
season. 
Table 3. — Outline of miscellaneous spraying experiments in the control of the 
blackhead fireicorm on the Portland-Sea view Cranberry Co. bog at Seaview, 
Wash.. 1919. 
Plat 
No. 
Spray materials, dosage, 
etc. 
Number of gallons used calculated per 
acre per application. 
May 13 
and 14. 
June 12. 
July 1 
and 2. 
July 16 
and 17. 
Aver- 
age per 
appli- 
cation. 
Total 
Total 
number 
number 
of ber- 
of ber- 
ries 
ries free 
exam- 
from 
ined. 
injury. 
Per cent.. 
388 
92.52 
402. 
95. 52 
735 
93.74 
737 
97.42 
Gain 
over 
check. 
Ill 
IV 
40 per cent nicotine sul- 
phate, 1-1,000+fish-oil 
soap, 2-50 , 
40 per cent nicotine sul- 
phate, 1-1,000+fish-oil 
soap, 2-50 
40 per cent nicotine sul- 
phate, 1-800 + fish-oil 
soap, 2-50 
40 per cent nicotine sul- 
phate, 1-800 + fish-oil 
soap, 2-50 
380 
380 
330 
300 
300 
280 
280 
320 
320 
280 
280 
480 
4M> 
333 
370 
297 
342 
Per cent. 
15.50 
18.50 
16.72 
20.40 
