STRAWBERRY ROOTWORM ON GREENHOUSE ROSES 43 
As shown in Table 18, the mortality in the preliminary pot ex- 
periments was promising, hence nine plots of five or six plants each 
were treated with sodium cyanide in solution. Sodium cyanide was 
also pulverized and then spread around the base of every plant in 
' three plots of five plants each. The mortalities resulting from these 
_ plot treatments are listed in Table 19. 
- 
|TABLE 19.—Results obtained in plot experiments with sodium cyanide, in solu- 
h 
| 
{ 
| 
I) 
! 
tion and pulverized, against larve and pupe of the strawberry rootworm 
but especially the wood ashes, are used extensively by florists. 
Number of lar- Number of lar- 
Period ve and pups Period ve and pups 
after | N after | Num- 
Dosage Treat be of Control || Dosage rer | per gt Control 
ment | P ants Exam- ment | P22US | Rxam- 
inedia|, Dead ined) ead 
| Grams | Days Per cent sree Days : 4 Per gene 
| Oe 4 7 57 4 TOO Sess 6 18 50. 
eyes 7 4 11 1 AOE | Roe ates ee 2 2 24 21 87. 5 
Lh == 4 4 28 4 1 Ete Fil fice en 6 3 20 13 65. 0 
lL hs 7 4 15 3 PAUS (cM aes 2 2 25 24 96. 0 
Th 8 3 17 1 DOH eae 6 3 21 11 52. 4 
ene 4 4 35 4 BIg ES: Sal ie 3 oa ae 8 5 16 4 25.0 
|| eee 8 7 57 1. VORB Ma 8 5 37 26 70. 3 
2 2 2 19 3 POMS ia oie as ae 8 5 21 20 95. 2 
1 Applied in pulverized form. 
In these experiments the mortality of larvae and pupe in soil 
which had been drenched with sodium cyanide was insufficient to 
justify its use as a means of destroying the soil stages. Moreover, 
the practical use of the pulverized crystals would be precluded 
because the collars of the plants were severely injured by this treat- 
ment. 
WOOD ASHES AND TOBACCO DUST 
Because of their fertilizing value, wood ashes and tobacco dust, 
It 
was thought that the free lye. present in wood ashes, and the nico- 
tine, which is an ingredient of the tobacco dust, might leach into the 
soil and be effective in killing the larve and pupe. To determine 
_ its effectiveness in three p ots containing 10 plants each, a handful 
_ of this mixture was applied around the base of each plant and then 
watered. Examinations of the larve and pupe in soil around the 
plants were made seven or eight days later, and the results are given 
in Table 20. 
? 
TABLE 20.—EHffects on strawberry rootworm larve and puve in soil treated with 
tobacco dust and wood ashes 
Number of Number of 
Period larvee pup Larve 
Material ae Tome Control Control Re 
ment pa Dead Epis mead control 
Days Per cent Per cent| Per cent 
SRADACCOLGUSE= 522) ke See 7 44 4 9.1 41 9 22.0 15.3 
Biigodrashes< 25) S0g9 seed ers a 8 36 PAA) Geoctay5 6) 33 7 21. 2. 13. 0 
Tobacco dust and wood ashes 
RTPIN Qe un eee na U 17 2 11.8 18 2 Tal 11.4 
