Scale
Scales are one of the most destructive insects on plants. TSU Extension Specialist Amy Dismukes talks about hard and soft scale and how to treat infestations on your plants.
Hard scale feeds on the very outside of the phloem layer of the plant so it is difficult to control with a systemic insecticide. They need to be controlled in the juvenile stage with horticultural oils or insect growth regulators like Talus. There are multiple generations of hard scale each year, but the best time to control them is in early spring when the crawlers are active. If you have a limited infestation, you can prune out and dispose of the problem branches.
Soft scales feed deeper in the phloem layer and suck more sap that they can use. Because they have more sap passing through them, they can be effectively controlled by systemic insecticides like Imidacloprid or Dinotefuran. They also only have one generation per year. Soft scale produce honeydew which provides a surface for fungus to grow. This fungus is called sooty mold and creates a black layer on leaves, patios, sidewalks, and cars that are under plants infested with sap-sucking insects like scale.
Related Videos:
What do I do about the scales on my euonymus?
Treating Crape Myrtle Bark Scale
Related Resources:
Armored (Hard) Scale - Trees and Shrubs
Soft Scales
Hard scale feeds on the very outside of the phloem layer of the plant so it is difficult to control with a systemic insecticide. They need to be controlled in the juvenile stage with horticultural oils or insect growth regulators like Talus. There are multiple generations of hard scale each year, but the best time to control them is in early spring when the crawlers are active. If you have a limited infestation, you can prune out and dispose of the problem branches.
Soft scales feed deeper in the phloem layer and suck more sap that they can use. Because they have more sap passing through them, they can be effectively controlled by systemic insecticides like Imidacloprid or Dinotefuran. They also only have one generation per year. Soft scale produce honeydew which provides a surface for fungus to grow. This fungus is called sooty mold and creates a black layer on leaves, patios, sidewalks, and cars that are under plants infested with sap-sucking insects like scale.
Related Videos:
What do I do about the scales on my euonymus?
Treating Crape Myrtle Bark Scale
Related Resources:
Armored (Hard) Scale - Trees and Shrubs
Soft Scales