Scale on a mugo pine.

Asked April 26, 2019, 10:53 AM EDT

I have 3 mugo pines that have pine needle scale. The middle one is still ok, but the other 2 are greatly infested. I cut off alot of damaged area on one that was the first to have this about 2 years ago and would like to know how to treat for a better outcome.

McLeod County Minnesota

1 Response

The best time to treat Pine needle scale, Chionaspis pinifoliae, on Mugo pine is after eggs hatch when the crawlers are first active and are searching for feeding sites, but before they begin producing their shells. A seasonal indicator to look for is when Lilacs are blooming. Combining systemic treatment with a crawler spray is the most effective method. Timing of these applications when the crawlers are active is crucial for effective control.

Spray treatment for crawler stage

  • Insecticidal soaps and horticultural oils.
  • Insect growth regulators (pyriproxyfen and buprofezin are available only to licensed applicators).
  • Residual insecticides (acephate, pyrethroids, carbaryl).
  • Time crawler spray applications for when crawlers are active for effective control.

Systemic management:

  • Use dinotefuran as a soil application or as a bark treatment in the spring.
  • Combine systemic treatment with a crawler spray for the most effective management.

Site on scale.

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