4 ARSENATE OF LEAD AGAINST TOBACCO HORNWORMS. 



the fact that many growers who suffered loss the year before were 

 extremely careful in making applications. 



On January 4, 1913, the senior writer interviewed several tobacco 

 buyers employed by the Italian Government. He was informed that 

 several crops of tobacco the grade of which was especially suitable 

 for the Italian Government were not bid upon because of the large 

 percentage of tobacco injured by Paris green. The buyer stated tliat 

 for one crop, had it been in average condition in regard to Paris- 

 green injury, he would have bid 8| cents per pound. In its damaged 

 condition, however, he did not believe the crop was worth over 5 

 cents per pound — a gross loss of 3^ cents per pound, or of $25 to $30 

 per acre. Another crop would have received an offer of 8 cents per 

 pound from the Italian buyers, but on account of Paris-green burn no 

 offer w^as made. This buyer thought the crop worth not more than 

 5^ cents — a gross loss of 2J cents per pound, or about $20 per acre. 

 A third crop had its value reduced by one-half, a fourth crop was 

 apparently worth about 5 cents per pound, and would ordinarily have 

 brought 9 cents. This is the report of buyers of the heavier types of 

 tobacco grown in this district. The lighter-bodied tobaccos undoubt- 

 edly suffered as severely and probably more severely than the heavier 

 tobaccos, because the lighter tobaccos are ordinarily more susceptible 

 to Paris-green injury. 



Paris green injures tobacco in two ways: First, by causing dead, 

 burned areas upon the leaves, where the powder has been collected by 

 the dews or washed down by the rains; second, by weakening the leaf 

 at the stalk. Light rains wash the insecticide into the axils of the 

 leaves, and the result is that many leaves drop off before cutting time 

 or become so weakened that they drop off when the plant is cut. 

 Such leaves are not a total loss, for they are collected and cured, but 

 they are a partial loss. They are light in weight and lack gloss and 

 elasticity. 



THE USE OF ARSENATE OF LEAD. 



Arsenate of lead causes none of the injury mentioned above. Ex- 

 periments performed under the direction of the senior writer showed 

 that powdered arsenate of lead may be put on a fresh sucker wound 

 in large quantities without causing any noticeable injury, and that 

 when applied to a torn or bruised leaf it produces no injury. Paris 

 green can not be applied to tobacco in the "graining" stage (i. e.. 

 when nearly ripe) in sufficient quantities to do good insecticidal work 

 without too grave danger of burning the plant. Arsenate of lead, on 

 the other hand, can be safely applied to tobacco in the "graining" 

 stage in quantities sufficient to produce satisfactory insecticidal re- 

 sults. Furthermore, arsenate of lead will cause no irritation to the 



