No problem with sesame oil other than perhaps a bit pricey. As with any oil, do not apply it if the temperature is above or soon to be above 80F; it will seriously burn your leaves.

Although generally considered safe, oils can injure susceptible plant species. Symptoms of plant injury (phytotoxicity) may be acute or chronic. They can include leaf scorching and browning, defoliation, reduced flowering and stunted growth. Phytotoxicity may be associated with plant stress, ambient temperature and humidity, and application rate. It can vary among plant species and cultivars. To reduce the risk of phytotoxicity, do not treat stressed plants. Apply when conditions are below 85 ðF degrees and 90 percent humidity. Applications during the summer season are best in the morning or late evening. The longer wet oil sprays remain on foliage, the greater the chance of phytotoxicity.

During winter it is best to apply oils only when temperatures are above 40 ðF. Apply dormant oils or higher rates of summer oils only after stems and buds have become winter-hardened and before buds begin to swell in the spring. Evergreen trees generally should be treated only by summer rates of all-season oils. Some evergreens, especially those with a glaucous (waxy) coat, may become discolored following an oil application. This usually does not harm the tree or shrub.

When treating a new kind of plant, it is best to apply horticultural oils to part of the plant or to a few small specimens before treating large quantities of foliage. With oils it is especially important to read, and follow label instructions and recommendations. Manufacturersâ labels provide useful information about sensitive plant species based on extensive testing. Some plants most commonly listed as being oil sensitive include azalea, carnation, fuchsia, hibiscus, impatiens, photinia, rose, cryptomeria, juniper, Japanese holly and spruce.

Oils have many characteristics that make them desirable to growers and homeowners. For example, they are low in toxicity to humans, wildlife and pets. Since oils are only active for a short time, they do not Scale insects can be controlled with horticultural oils. Oils will separate from the carrier. Agitation is necessary to keep oils in solution. affect insect predators or parasitoids unless they are exposed to the direct spray. Oils evaporate quickly and do not generally contaminate the soil or groundwater sources. Plant and fish oils are broken down rapidly by microorganisms on plants or soil, and pose minimum risk to non-target organisms. Oils are also considered one of the few classes of pesticides to which insects and mites have not developed resistance.

Mike