Gloomy scale on red maple - Ask Extension
We have 26 red maples in our community which have a heavy infestation of Cloudy Scale. Some of the branches are bare as a result of this infestation....
Knowledgebase
Gloomy scale on red maple #877610
Asked July 17, 2024, 12:04 PM EDT
We have 26 red maples in our community which have a heavy infestation of Cloudy Scale. Some of the branches are bare as a result of this infestation. The trees are about 20 feet from homes. What is the recommended treatment at this time of the year?
Howard County Maryland
Expert Response
Gloomy Scale has one generation per year, and the timing of treatment method will depend on which approach is used (dormant oil applications, topical insecticides like IGRs (insect growth regulators), or systemic plant-absorbed insecticides). Bare branches will not recover because they are too weak or already dead and will need to be pruned off.
The most vulnerable life stage for scale insects is the crawler period, which is when eggs hatch and the newborn juveniles wander about looking for a place to settle-down and feed. (After settling, they will not move, and their waxy "shell" that starts to form will protect them from most pesticide sprays.) Gloomy Scale crawler windows depend on temperature trends, though the average timing of their emergence is between mid-July and late August, so monitoring can begin right now. In 2022, for example, Gloomy Scale crawlers were observed in Howard County already well into the emergence period in late June, so this year's hot weather may have shifted the average emergence period earlier as well.
Information about pesticide options are included in the management section of our Introduction to Scale Insects page. Commercial pesticide applicators (landscapers, arborists, nursery sprayers, etc.) often use either Distance or Talus to treat scale crawlers; both are classified as IGRs. With a crawler emergence period of around 6-8 weeks for this scale species, one or more repeat applications of pesticide will probably be needed, but the usage directions on the product chosen will need to be followed, as application instructions can differ.
Miri
The most vulnerable life stage for scale insects is the crawler period, which is when eggs hatch and the newborn juveniles wander about looking for a place to settle-down and feed. (After settling, they will not move, and their waxy "shell" that starts to form will protect them from most pesticide sprays.) Gloomy Scale crawler windows depend on temperature trends, though the average timing of their emergence is between mid-July and late August, so monitoring can begin right now. In 2022, for example, Gloomy Scale crawlers were observed in Howard County already well into the emergence period in late June, so this year's hot weather may have shifted the average emergence period earlier as well.
Information about pesticide options are included in the management section of our Introduction to Scale Insects page. Commercial pesticide applicators (landscapers, arborists, nursery sprayers, etc.) often use either Distance or Talus to treat scale crawlers; both are classified as IGRs. With a crawler emergence period of around 6-8 weeks for this scale species, one or more repeat applications of pesticide will probably be needed, but the usage directions on the product chosen will need to be followed, as application instructions can differ.
Miri
