Sulfur for dusting purposes must be especially fine. Finely ground sulfur-flour is preferable. Powdered arsenate of lead in the proportion of ten pounds to ninety pounds of sulfur should generally be used, not only because of the insecticidal value of the arsenate of lead, but also because of its effect on the physical condition of the sulfur. By combining powdered arsenate of lead and sulfur - flour, the resulting dust is fluffy and consequently better distribution and better adhesive qualities are obtained. The dilution of the sulfur with finely powdered lime is not to be recommended because the lime appears to have a detrimental effect on the fungicidal action of the sulfur.
Finely powdered gypsum or other inert carriers may be added, but their use is of doubtful value.