Red Oak Tree with Kermes scale (18 yr. old tree)
This scale was very recently treated with Safari Systemic Insecticide root zone injection and the company recommended a fall merit injection. My concern is that the leaves are still breaking off in large clusters. Should I expect this to continue and if so how long is normal?
Thanks for a reply.
Worried tree mom in Denver
Denver County Colorado trees and shrubs
Sorry for the delayed response, worried tree mom.
There's much unknown about the bacterial disease (Brunneria or "drippy nuts" disease) transmitted by Kermes scale into red oak. Even if Kermes is controlled by systemic insecticides (Merit, Safari), by crawler sprays in Oct/Nov or by spraying dormant oils in Feb/March, the bacteria in the oak's sap remain.. The bacteria are likely causing the twig drop.
You should expect twig drop to continue, but for how long is unclear.
Try to keep the oak as healthy as possible by watering during dry spells in winter and with light fertilization in May.