D2, CIRCULAR 639, U. S. DEPARTMENT OF AGRICULTURE 
cloud formed will settle on the fohage. This is essential to avoid 
serious burning of the maturing leaves. In high tobacco the dust- 
gun nozzle should be directed to the rear of the operator so that as 
much as possible he will avoid inhaling the dust. Applications of 
the poison mixture should be made at the rate of from 7 to 8 pounds 
per acre. Poisoning operations should commence as soon as the 
worms begin to hatch in appreciable numbers, and the frequency of 
the applications during the remainder of the season will depend on 
the abundance of the hornworm and the purpose for which the to- 
bacco is grown. Filler tobacco will ordinarily be sufficiently protected 
by about one application each week, whereas crops raised for cigar 
binder may require two applications of the poison mixture each week. 
The paris-green-lime mixture can be recommended for use only 
with an efficient dust eun and in the manner described. It cannot 
et = 
FicguRE 23.—The proper method of applying poison dust to young, sun-grown 
tobacco. When the plants are not over knee high, the dust should be directed 
against the foliage in order to obtain the best results. 
be recommended for use as a spray or for application in dust form 
by means of the sack “shaker” method, or by any other method that 
results in heavy dosages of the poison being deposited directly upon 
the plants. 
Light applications of undiluted paris green may be used to control 
the hornworm on sun- grown tobacco in “this region. The poison is 
usually applied at the rate of from 1 to 2 pounds per acre with the 
dust-gun nozzle held in the center of the space between the tobacco 
rows. Growers accustomed to the use of the undiluted arsenical 
frequently obtain a satisfactory degree of control with little foliage 
injury, while in other instances severe burning results from this 
practice. 
