26 MISC. PUB. 52 6, U. S. DEPT. OF AGRICULTURE 



expelled under a gas-proof cloth, or trailer. This cloth trailer is 100 

 feet long and is drawn over the field at the rate of 100 feet per minute. 

 Caution. — Nicotine and the fumes given off by it are poisonous, 

 and great care should be exercised in handling. 



OIL DUSTS 



Oil dusts usually contain about 2 to 5 percent of lubricating oil of 

 80 to 110 seconds viscosity (Saybolt, 100° F.) and may include various 

 insecticides or fungicides. The oil is added to improve the adhesive 

 properties of the dust. 



An oil dust which may be used for control of the oriental fruit 

 moth and brown rot on peach consists of 60 pounds of dusting sulfur, 

 35 pounds of dusting talc, and 5 pounds of lubricating oil. This 

 should be applied at weekly intervals for a period of 4 to 5 weeks 

 before harvest. It has little or no toxicity to the insect but acts as 

 a mechanical barrier and irritant. 



A mixture which has been used for the plum curculio on peach 

 consists of 30 pounds of dusting sulfur, 30 pounds of dusting talc, 

 25 pounds of hydrated lime, 10 pounds of lead arsenate, and 5 pounds 

 of lubricating oil. 



Oil dusts containing pulverized rotenone-bearing roots are used to 

 control the pea aphid. 



Oil dusts may be prepared in the same manner as nicotine dusts. 

 Thorough mixing to break up lumps is necessary. 



PARADICHLOROBENZENE 



Paradichlorobenzene (C 6 H 4 C1 2 ), known to the trade as P. D. B., 

 is a white, crystalline compound. It volatilizes slowly at 80° F., has 

 a distinctive odor, and the vapor formed is noninflammable and 

 penetrating. 



Paradichlorobenzene is employed to a limited extent as a soil fumi- 

 gant to kill various insect pests, such as root aphids, wireworms, and 

 the sweetpotato weevil. Its principal use as an insecticide, however, 

 is for the control of the peach tree borer. The crystals are spread in 

 a circle around the base of the peach tree about 1 to iy 2 inches from the 

 trunk and then covered with a mound of soil. This is done in the early 

 fall or spring at rates varying from 14 to 2 ounces per tree, depending 

 upon age. A solution in cottonseed oil is also applied as a paint in 

 the control of the lesser peach borer. An effective mixture consists of 

 1 pound of paradichlorobenzene dissolved in 2 quarts of cottonseed 

 oil. It is sometimes necessary to warm the cottonseed oil to room 

 temperatures to aid in dissolving the paradichlorobenzene. Apply 

 only to well-defined infested areas of the trunks or limbs. 



Paradichlorobenzene crystals, at the rate of 1 pound per 100 square 

 feet, are spaded into greenhouse soils for the control of garden centi- 

 pedes. This treatment must be applied 3 weeks before replanting the 

 beds. 



Caution. — Paradichlorobenzene should be stored in airtight 

 containers to avoid loss by evaporation. Do not expose foodstuffs 

 to the vapor of this chemical, as they absorb it and are then unlit 

 for consumption because of a pronounced odor or taste. 



