16 



Circular 107 



such a height above the plants that the cone of spray which it deliv- 

 ers completely envelopes the top of the plant; (8) adjust the side 

 nozzles at such a distance from the plant and such a height above 

 the ground that the side of plant facing the nozzle will be from top 

 to soil completely enveloped by the cone of spray delivered from it. 



Fig-. 11 



Engine-Driven Potato Sprayer Showing Details of Nozzle 

 Arrangement, Etc. 



When members of the nightshade family are grown under 

 glass, either in cold-frames or greenhouses, and become infested 

 with lice, they can best be protected by fumigation with nicotine or 

 hydrocyanic acid gas. The former is probably the most practicable 

 except under greenhouse conditions, when a man experienced in the 

 use of hydrocyanic acid gas is available. Tobacco paper, such as 

 "nico fume," may be purchased from dealers in florists' supplies and 

 used. While the amount to use will be marked on the package, the 

 grower may find it necessary to experiment until he finds the dose 

 that will destroy his lice, because the tightness of every enclosure dif- 

 fers from all others. 



In dealing with the lice problem in low cold-frames where the 

 burning of papers makes too much fire, 40 per cent nicotine may be 

 evaporated over a small alcohol lamp. In such cases the strength of 

 charge best suited will have to be determined by experiment. Start 

 trials with strength recommended on the package. The best results 



