Some gardening tasks need to be done within a specific time frame. For example: pruning roses (early February), fertilizing azaleas (after blooming), planting foxglove (in the fall). Something else you should consider doing right now (in the spring) is treating any of your scale infested plants with an oil-based spray.
The hot summer sun, humid air, and rain showers limit the time frame in which we can apply oil-based sprays. Think of a beam of sunlight going through a magnifying glass in the middle of the summer. If applied in the summer sun, an oil-based spray will burn or scorch the leaves of your plant. The time to spray oil sprays is now, before summer weather settles in. I do not recommend spraying an oil spray when the daytime temperatures are consistently above eighty-five degrees.
Horticulture oil, or any oil-based sprays, are most used to treat scales. Do you know what scales are? They’re the small, white spots, typically on the underside of a plant’s leaves. Although oil sprays are most used to treat scales, there are several other things it will protect against, such as: mites, aphids, mealybugs, thrips, powdery mildew, and black spot. Commonly treated plants include, but are certainly not limited to azaleas, camellias, sasanquas, wax myrtle, Ligustrum, viburnum, hollies, magnolias and more!
You can use an oil spray on pretty much anything, just remember two things.
- Don’t use it during the hot summer months – June through September. And,
- Don’t use it if your plant is in bloom, or about to bloom. Wait until after a bloom
If your infestation is particularly bad, I recommend spraying in the spring and fall with an oil spray, and then supplementing in the summer with a systemic insecticide. This is a surefire recipe for getting your scales under control.
Scales are living, immobile insects that can live on almost any plant. They’re commonly found on the underside of a plant’s leaves. The scales will need to be entirely coated with the oil spray for the scales to die. Important note: Do not apply an oil spray within 8 hours of a rain shower – that is either before or after application.
When treating with a systemic insecticide, the scales will absorb the chemical through the leaves, and then die. Either way, you should not expect the scales to fall off the leaves quickly. They are so tightly stuck on the leaves, that even though they might be dead, it will take a few weeks for them to flake off.
