The following are highlights and updates about samples and questions recently received in the Clinic:
We are receiving blue spruce samples with sudden needle drop (SNEED) and Rhizosphaera needle cast disease. It is not known if treatment for Rhizosphaera needle cast will help control SNEED. More information about these two diseases can be found online in the January 7, 2009 Horticulture & Home Pest News and from the Missouri Department of Conservation.
Oystershell Scale. Several calls and samples this spring have involved large number of oystershell scales on maples and other trees. Oystershell scales are named for their elongate, curved appearance that resembles miniature oyster shells. See photos below. Oystershell scales are 2 – 3 mm in length and found on the stems of many different host plants. Contact insecticides are only effective for the control of scale insects right after egg hatch when the first instar nymphs (AKA, "crawlers") are present. See ISU Extension publication IC-415, Scale Insects on Ornamental Plants, for more information.
Links to this article are strongly encouraged, and this article may be republished without further permission if published as written and if credit is given to the author, Horticulture and Home Pest News, and Iowa State University Extension and Outreach. If this article is to be used in any other manner, permission from the author is required. This article was originally published on May 12, 2010. The information contained within may not be the most current and accurate depending on when it is accessed.