By Mary Small, Colorado State University Cooperative Extension, Urban Integrated Pest Management
If the branch tips of your red oak are dropping off, it could be because of the insect Kermes scale.
Adults are about ¼ inch in diameter, rounded and tan-colored. They look similar to buds or other plant growth. Heavy infestations cause "flagging", where the leaves on branch tips turn off-color, droop and often drop off. Infested trees have reduced growth and vigor. Eggs hatch in September and October and crawlers move to over-wintering sites on tree branches and trunks.
Crawler sprays may be applied in early fall. Over-wintered scales can be treated with dormant oils in late winter or early spring.
Photo: Judy Sedbrook
© CSU/Denver County Extension Master Gardener 2010
888 E. Iliff Avenue, Denver, CO 80210
Date last revised: 01/05/2010