December, ’20] MELANDER: CODLING MOTH SPRAY INDEX 
457 
To illustrate, a few citations may be made from codling moth spray¬ 
ing data. 
Ratio 
.4 < . 
«# 
Total 
Total 
Per cent 
worms to 
No. 
Treatment 
worms 
stings 
wormy 
stings 
1 . 
None . . 
1,502 
79 
85.9 
18.1 
2. 
MgAs: 1/100, 1/100, 1/100, 1/100 
202 
464 
16.8 
.436 
3. 
ZnAs: 1/100, 1/100,1/100, 1/100 
70 
227 
6.5 
.308 
4. 
CaAs: 1/100, 1/100, 1/100, 1/100 
135 
395 
9.2 
.292 
5. 
LdAs: 1/80,1/80,1/80,1/80.... 
448 
1,950 
12.2 
.276 
6 . 
LdAs: 1/20,1/50,1/80,1/50.... 
96 
348 
9.0 
.276 
The foregoing results were obtained last year on 25-year old Ben 
Davis trees at Spokane. Judged by the per cent of worminess the 
lead arsenate spray was inferior to calcium arsenate and zinc arsenite. 
The coefficient of effectiveness places the lead arsenate treatment first. 
Comparing examples 5 and 6 one draws the conclusion merely that more 
larvae hatched on the trees of 5 in proportion to the number of apples, 
for the coefficient of effectiveness is exactly the same. 
No. 
Treatment 
Wormy 
apples 
Stung 
apples 
Per cent 
wormy 
Ratio 
wormy to 
stung 
7. 
LdAs: 1/100, 1/100, 1/100, 1/67, 
1/50. 
53 
51 
1.51 
1.04 
8. 
LdAs and caseinate, same strengths 
80 
61 
1.24 
1.31 
9. 
CaAs and caseinate, same strengths 
104 
17 
1.6 
6.12 
Citations 7-9 are from Lovett's recent Bulletin 169. Commenting 
on his results he states “the variations in the percentage of worms in 
the different plots are so slight as to be within the scope of experi¬ 
mental error, and comparative results are practically nil.” However, 
the index numbers show that the lead arsenate killed proportionally 
about three times as many worms as did the calcium arsenate. The 
information in this case is derived from the number of stung and of 
wormy apples, instead of the total number of stings and of worms. 
Though possibly less accurate such data may be similarly compared. 
Leroy Childs recently presented some interesting figures from his 
tests of the spray-rod and spray-gun. From the criterion of final 
worminess his conclusion was that the gun gave best results. 
No. 
Treatment 
Per cent 
Per cent 
Ratio 
worms to 
10. 
Gun; counts up to 12-ft. level. 
stung 
. 1.79 
wormy 
.79 
stings 
.44 
11. 
Rod; counts up to 12-ft. level. 
. 3.9 
.97 
.25 
12. 
Gun; counts 12-ft. to top of tree. 
. 2.7 
3.2 
1.18 
13. 
Rod; counts 12-ft. to top of tree. 
. 4.0 
3.8 
.95 
14. 
Dust. 
. 1.19 
3.08 
2.60 
15. 
Unsprayed checks. 
. 1.86 
12.0 
6.45 
