THE BLACKHEAD FIREWOKM OF CRANBEREY. 



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 and 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 larvse 

 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." In order to catch the late-hatching 

 larvse 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 17) 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. 



Wliile 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 tlie 

 blackhead fireivorm on the Fortland-Seavie/w Cranherry Co. hog at Seat>iew, 

 Wash., 1919. 



Plat 

 No. 



Spray materials, dosage, 

 etc. 



Number of gallons used calculated per 

 acre per application. 



Total 

 number 

 of ber- 

 ries 

 exam- 

 ined. 



Total 

 number 

 of ber- 

 ries free 



from 

 injury. 



May 13 

 and 14. 



June 12. 



Julyl 

 and 2. 



July 16 

 and 17. 



Aver- 

 age per 

 appli- 

 cation. 



380 



300 



320 





333 



388 



Per cent. 

 92.52 



380 



300 



320 



480 



370 



402 



95.52 



330 



280 



280 





297 



735 



93.74 



330 



280 



280 



480 



342 



737 



97.42 



Gain 



over 



check. 



I 



II.... 

 Ill .. 

 IV... 



40 per cent nicotine sul- 

 phate, 1-1,000-l-flsh-oil 

 soap, 2-50 



40 per cent nicotine sul- 

 phate, 1-1,000-ffish-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 -I- fish-oil 

 soap, 2-50 



Per cent. 

 15.50 



18. .50 

 16.72 

 20.40 



