Insecticidal Soap

Registered formulations of insecticidal soap are important management tools for effective pest management programs designed to reduce populations of insect and mite pests on landscape and nursery plants. A mode of action of insecticidal soap is a physical one. The active ingredients in insecticidal soaps (salts of fatty acids) disrupt the cell membrane of the life stage of a vulnerable pest. Some formulations of insecticidal soap are labeled for management of adelgids, aphids, elm leaf beetle larvae, sawfly larvae, lace bugs, leafhoppers, mealybugs, rust mites, spider mites, plant bugs, psyllids, scale insects, exposed thrips, and whiteflies. Application of insecticidal soaps may help conserve the adult stages of beneficial insects such as lady beetles, lacewings, flower or hover flies, and wasps because these insects have a thicker cuticle. Hard water in a tank mix may cause precipitation of the active ingredient in insecticidal soaps. Be sure to check the hardness of your tank mix water before you mix and apply a formulation of insecticidal soap. Follow all specimen label precautions when applying any formulation of insecticidal soap in order to prevent plant phytotoxicity.

References

Baxendale, R. W., and W. T. Johnson. 1988. An evaluation of dormant oil phytotoxicity on six species of woody ornamentals. J. Arboric. 14: 102-105.

Baxendale, R.W., and W. R. Johnson. 1988. Evaluation of summer oil spray on amenity plants. J. Arboric. 14: 220-225.

Davidson, N.A., J. E. Dibble, M. L. Flint, P. J. Marer, and A. Guye. 1991. Managing insects and mites with spray oils. Univ. Calif., Div. Agri. and Nat. Res., Publ. 3347, 47 pp.

Johnson, W. T. 1989. Dormant spraying with horticultural oils. Arbor Age 9: 12-14.

Johnson, W. T. 1986. Horticultural oils. Pennsylvania Nurserymen’s News (newsletter), pp. 13-16.

Johnson, W. T. 1985. Horticultural oils. J. Environ. Hort. 3: 188-191.

Johnson, W. T. 1983. New label of horticultural spray oil. J. Arboric. 9: 206-207.

Johnson, W. T. 1980. Spray oils as insecticides. J. Arboric. 6: 169-174.

Johnson, W. T., and D. L. Caldwell. 1987. Horticultural oil sprays to control pests of landscape plants: An industry survey. J. Arboric. 13: 121-125.

Miller, F. D. 1989. The use of horticultural oils and insecticidal soaps for control of insect pests of amenity plants. J. Arboric. 15: 257-262.