HANDBOOK ON INSECT ENEMIES OF FLOWERS AND SHRUBS 101 



rather concentrated form in cavities and 

 depressions, as in certain pyramidal- 

 type junipers. It is advisable to wash 

 or syringe the more tender plants with 

 water an hour or so after applying the 

 treatment. Although oil emulsions can 

 be prepared at home, it is much more 

 satisfactory to purchase the prepared 

 product and use it at tho dilutions recom- 

 mended by the manufacturer. 



White-oil emulsions are often used as 

 spreading or wetting agents with other 

 sprays. When so used they increase the 

 effectiveness of these sprays against 

 scale insects, mealybugs, mites, and the 

 common red spiders, because the waxy 

 covering over the insect's body is more 

 easily penetrated and wetted. The tox- 

 icity -of oil sprays is enhanced by the 

 addition of nicotine, pyrethrum, or 

 derris or cube extracts. 



Oil-Nicotine-Soap Spray 



The following combination spray may 

 be used on hardy shrubs for the control 

 of young scale insects during their 

 hatching period, and also against lace- 

 bugs and probably other sucking insects : 



y 2 Pint or 1 cupful of white-oil emulsion (83 percent 



of oil). 

 \i pound or \\h cupfuls of soap flakes. 

 4 teaspoonfuls of 40-percent nicotine sulfate. 

 Z\i gallons of water. 



Caution. — See "Caution" under 

 "Nicotine" page 98. 



Oil-Rotenone Spray 



Another spray combination that mav 

 be used in controlling lacebugs on hardy 

 shrubs, such as azalea and rhododen- 

 dron, is as follows: 



4 ounces (8 level tablespoonfuls) of white-oil emulsion. 

 Yi ounce (5 level tablespoonfuls) of o>rri? powder 



(4 percent rotenono) . 

 3 gallons of water. 



Dormant Oil Emulsion 



There are also available on the market 

 a number of so-called dormant oil emul- 

 sions. These are made of less highly 

 refined oils than the white-oil emulsions, 

 are used primarily for spraying on hardy 

 shrubs and trees during the dormant 

 season, and may be used in place of the 

 dormant miscible oils, discussed below. 

 They should be diluted with water as 

 indicated on the label or in the instruc- 

 tions accompanying these proprietary 

 materials, since the oil content of the 

 different products varies. 



Miscible Oils 



Several proprietary miscible oils are 

 used in combating scale insects and 

 some other insects on hardy plants. 

 When diluted with water they form a 

 milklike spray mixture. These oils are 

 obtainable under various trade names 

 and should be used as directed by the 

 manufacturers. Miscible oils are pri- 

 marily used while the plants are dor- 

 mant. They are usually diluted at the 

 rate of about 1 gallon (or part by vol- 

 ume) of the oil to 15 or 20 gallons (or 

 parts) of water for deciduous shrubs and 

 trees, and 1 gallon to 25 or 30 gallons of 

 water for evergreens. The oil should 

 be well stirred before it is used. The 

 sprayer should be free from alkalies, 

 acids, and other impurities. Soft water 

 should be used when available. The 

 oil should be poured into the tank and 

 the diluting water added to it. The 

 solution should be kept thoroughly mixed 

 to prevent the accumulation of free 

 oil on the surface. As with other min- 

 eral-oil sprays, the liquid should not be 

 allowed to puddle about the base of the 

 plants. Dormant oil sprays should not 

 be applied in freezing weather. It is 

 preferable to spray when the temperature 

 is 40° F. or above and there is not likely 

 to be freezing weather until the spray 

 dries. Although dormant spraying may 

 be carried on in the fall, winter, or 

 spring, probably the safest period is in 

 the spring just before the new growth 

 starts. 



Sulfur 



Dusting Sulfur 



Finely ground sulfur, called dusting 

 sulfur, is a contact insecticide and is 

 also used as a fungicide against certain 

 plant diseases. It may be applied as a 

 dust for the control of the red spider 

 (p. 11), the tarnished plant bug (p. 35), 

 the phlox plant bug (p. 67), and thrips. 

 Dusting sulfur is also used in combina- 

 tion with pyrethrum powder against 

 leafhoppers (p. 10) and plant bugs. It 

 may be used in the preparation of 

 nicotine (p. 98) and rotenone-containing 

 dusts. 



Sulfur may be used as a diluent for 

 lead arsenate to make a stomach- 

 poison dust mixture. Part of the 

 sulfur may be replaced with such 

 diluents as hydrated lime, tobacco 

 dust, gypsum, kaolin, talc, or cheap 

 flour. Where sulfur is being used, the 

 addition of lead arsenate as indicated 

 in the formulas given under Lead 

 Arsenate as a Dust (p. 96) will control 

 such chewing insects as young cater- 

 pillars and sawfly larvae. 



