While oil treatments have historically targeted fruit trees and woody ornamentals, several different types of pesticide oils are currently marketed for house plants, flowers and vegetables. Commercial oil products include emulsifiers to enable the oil to mix readily with water. These emulsifiers are generally considered to be inert, but may have some insecticidal properties. Oil formulations are generally designed to be mixed with water at concentrations of 0.5-2.0 percent (volume/ volume). When applying oils, it is best to agitate hand pump sprayers frequently and keep tank spray agitators running. This reduces the risk of oil separation that could result in sprayer clogging, uneven plant coverage and possible plant injury.
Oils will separate from the carrier. Agitation is necessary to keep oils in solution.
When mixed with other pesticides, oils can enhance application efficiency. Oils often act as surfactants, and improve plant coverage and penetration of pesticides into leaf surfaces. Always read pesticide product labels carefully to make sure the product can be mixed with oil. Most labels prohibit the use of sulfur pesticides within 30 days of oil treatment. Oils may be incompatible with copper applications in some crops.
