ARSENATE OF LEAD FOR TOBACCO HORNWORMS. 5 
The results upon this field emphasize the fact that a clean sweep 
of the tobacco worms can be made with arsenate of lead without 
danger of burning the tobacco. ‘The tobacco in this field was well 
advanced and at a stage in which Paris-green burn was very likely 
to occur. 
HOW TO APPLY ARSENATE OF LEAD TO TOBACCO. 
Paris green is generally applied to tobacco by means of a dust 
gun and without the admixture of a carrier. On the other hand, 
arsenate of lead must be mixed with a carrier im order to secure an 
even and thorough distribution. Several carriers have been tested 
with this insecticide. Finely sifted air-slaked lime did not dust 
evenly. Road dust and land plaster proved to be too heavy. The 
best results were obtained with finely sifted, freshly burned wood 
ashes. At least an equal bulk of the wood ashes should be used. 
Mix the arsenate of lead and ashes very thoroughly and apply while 
there is dew upon the tobacco and when there is no breeze. Even if 
very dry and finely sifted ashes are used, unsatisfactory results will 
be obtained unless the application is made with a powerful dust gun. 
The hand-power dust guns now in general use do not furnish suffi- 
cient power to make anything like a satisfactory and effective appli- 
cation. Special guns that will perform satisfactory work are gradu- 
ally coming on the market. The new guns have a fan with a diame- 
ter of 8 inches, whereas the old guns have a fan diameter of only 6 
inches. The new guns have also an auxiliary dust chamber, which 
is very essential, because the dust containers of the old guns are so 
small that they have to be refilled five or six times for each acre 
dusted. Two refillmgs of the new guns will be sufficient for dusting 
an acre. 
To secure the best results, dust the tobacco when dew is upon the 
plants and when there is no breeze. The use of a carrier that does 
not dust evenly, the application of the insecticide when there is too 
much breeze, and the use of too small a dust gun are all certain to 
give unsatisfactory results. Avoid these mistakes, and satisfactory 
results will be secured. 
Thoroughness of application can not be too strongly recommended. 
When tobacco worms are numerous a poor application of an insecti- 
cide will miss worms enough to ruin in two days more than enough 
tobacco to pay for the whole application. Make the application 
thorough. 
THE GRADE OF ARSENATE OF LEAD THAT SHOULD BE USED. 
Arsenates of lead may be broadly divided into two forms, tri- 
plumbic and diplumbic. Theoretically the triplumbic form may 
contain 25.58 per cent of arsenic oxid, while the diplumbic may 
