6 MISC. PUB. 526, TJ. S. DEPT. OF AGRICULTURE 



Mexican bean beetle, when used at the rate of 6 pounds to 100 gallons of 

 water, it is of more value against flea beetles and blister beetles. It 

 may cause foliage injury. To reduce foliage injury, alkaline waters 

 and those containing sulfates should not be used with this material. 

 Caution. — Barium fluosilicate is very poisonous to higher ani- 

 mals and man. Observe care in its use. For spray-residue 

 tolerance see page 3. 



BENTONITE 



Bentonite is a naturally occurring, light-colored clay. Chemically, 

 it is chiefly a hydrous silicate of aluminum, calcium, and magnesium ; 

 but a variety of other compounds may be present, depending upon the 

 source of the material. 



There are two general classes of bentonites, the swelling and the 

 nons welling. The former is used to dilute insecticidal and fungicidal 

 dusts, as an emulsifier for home-mixed oil emulsions, and in the prepa- 

 ration of tank-mixed and proprietary nicotine bentonite sprays. 



The principal source of the swelling type is the Black Hills region 

 of Wyoming and South Dakota, and the name "Wyoming bentonite" 

 is generally used to distinguish it from nonswelling clays. When wet 

 it will absorb water and swell to from 7 to 11 times its dry volume, 

 forming a gelatinous mass. 



Most of the bentonites, both the swelling and nonswelling types, will 

 react with nicotine to form a nicotine bentonite in which most of the 

 nicotine is insoluble in water, so that the combination acts as a stomach 

 poison rather than a fumigant or contact insecticide. At present 

 Wyoming bentonite is preferred for use with insecticides. It is obtain- 

 able either as a fine powder, which is preferred when used as a diluent, 

 or in fine pellets for use in making tank-mixed oil emulsions or nico- 

 tine-bentonite sprays. (See Nicotine Bentonite, also Mineral Oil.) 



BETA NAPHTHOL 



Beta naphthol (C10H7OH) is a slowly volatile, crystalline compound 

 that is used to impregnate corrugated paper bands, for placing around 

 the trunks of mature apple trees to trap and kill codling moth larvae. 



Rolls of single-faced corrugated paper 2 inches wide may be dipped 

 in a hot (250° F.) solution of 1 pound of beta naphthol (technical) 

 in 1.5 pints of lubricating oil having a Saybolt viscosity of 100-300 

 seconds at 100° F. The mixture can be used cold if diluted with gaso- 

 line. The chemical coating should be from 0.3 to 0.5 ounce of beta 

 naphthol plus oil per linear foot of band, the smaller quantity being 

 used in the Pacific Northwest. 



Some persons with a delicate skin are very sensitive to beta naph- 

 thol and may experience a burning sensation when working with it, 

 but the effect is only temporary. Gloves may be worn to avoid this. 



Prepared bands may be purchased in 250-foot rolls. 



BORDEAUX MIXTURE 



Bordeaux mixture is the name applied to sprays made by combining 

 dilute solutions of copper sulfate (bluestone) with lime and water. 



