THE COLORADO POTATO BEETLE IN VIRGINIA. 7 
THE TRACTION POWER SPRAYER IN USE. 
On several occasions a large traction power sprayer, working at a 
pressure of from 90 to 150 pounds, was used, operating on 5 or 6 rows 
at a time. The application with this machine was very effective, 
the plants being thoroughly sprayed above and from below, and 
were thus completely covered with the mixture. With from 2 to 4 
pounds of Paris green to 50 gallons of water this machine did very 
effective work in the control of the larvae in large plats of from 30 to 
50 acres. 
This machine was used for demonstration, as the small sprayers 
employed in the locality are usually of such a type as to apply the 
insecticide at a very low pressure; in fact, doing little better than 
merely sprinkling the upper surface of the vines. It is hoped that 
the truckers will take advantage of this practical demonstration to 
the extent of purchasing similar high-grade machines for doing this 
work. The work done by the traction dust distributors is of value, 
but on account of the higher cost of the insecticide applied in the form 
of dust it is desirable that sprayers should replace the dusters, even 
without considering damage to later crops resulting from the use of 
land plaster. If lime should replace the plaster in this mixture, at 
least for a time, the resultant acidity of the soil would be counter- 
acted and more favorable soil conditions would follow, thus preventing 
fertilizer injury from this source. 
The amount of lime distributed by a properly combined spray of 
Bordeaux mixture or of Paris green with lime is a negligible quantity 
in any case, while a decidedly beneficial effect is noted as a result of 
Bordeaux mixture applications, the yield being increased by from 40 
to 50 bushels per acre in several experiments conducted by the New 
York (Geneva) stations Paris green is admitted to possess about 
one-fourth the fungicidal value of Bordeaux mixture, but applied 
alone is quite likely to injure the vines, while Bordeaux mixture seems 
to prevent injury by any arsenical applied with it, even in the case 
of white arsenic-sal soda mixture. It has also been noted that the 
potato beetles dislike plants sprayed with Bordeaux mixture and 
when ready to oviposit leave such plants for those which have not 
been so treated. Both Paris green and arsenate of lead have yielded 
very satisfactory results as applications for killing beetles already on 
the plants, while the Bordeaux mixture acts as a repellent. The cost 
of material and expense of application for a Paris green or arsenate 
of lead spray, with Bordeaux mixture, is about 95 cents per acre, 
while the application of Paris green and land plaster by plantation 
methods costs nearly $4.20 per acre. The value of the copper unit, 
one of the active constituents of Bordeaux mixture, as a fungicide 
a Bull. 290, Nev/ York (Geneva) Agr. Exp. Sta., 1907. 
66513°— Bull. 82—12 2 
