This was a year of spruce! Of all the trees in Iowa landscapes, we receive the most samples of sick spruce trees. Our most common diagnoses for spruce in 2017 were Stigmina needle blight, Rhizosphaera needle cast, Sudden needle drop, Spruce spider mite, Spruce bud scale and suspected environmental stress.
Junipers were also common samples with spider mites, while we received fir, pine and arborvitae trees samples where no pathogens were found but based on the symptoms, the clues provided by the client and digital photos we suspected an abiotic problem related with any environmental stressor might be the cause of the symptoms.
In the category of broadleaf tree oaks are commonly submitted. In 2017 the following problems were our most common diagnoses were bur oak blight in bur oaks and two-lined chestnut borer. We also diagnosed abiotic disorders on a wide variety of trees (oaks, maples, birch, redbuds, among others), many times we suspect the tree decline was related to planting problems. When planting new trees prevent establishment issues by given the tree the best possible chance. Good recommendation to plant and care for trees can be found on the publication Community Tree Planting and Care Guide which can be downloaded for free from the extension store.
Notable in plant disease diagnoses were Verticillium wilt on magnolia, lilac, and coneflower. We also confirmed hops downy mildew and Apple mosaic virus in hops samples.
The PIDC continues working with the Iowa DNR and the Iowa Department of Agriculture and Land Stewardship to track infestations of emerald ash borer in Iowa. For most up to date emerald ash borer distribution maps visit our emerald ash borer FAQ page.
An invasive insect such emerald ash borer present an opportunity for homeowners, cities and land manager to rethink the importance of tree species diversity planning. For information on small trees and shade trees to consider or finding the right species to plant, consult the extension publication Small-stature Trees for Iowa - Ash Alternatives and Shade Trees for Iowa - Ash Alternatives.
Other insect sample we received included lace bugs, spider mites, bed bugs, American dog ticks, as well as, lone star and blacklegged ticks. As we close out 2017 the Plant & Insect Diagnostic Clinic (PIDC) is preparing for the big move into the new Advanced Research and Teaching Building. We are excited to move into our new space because we will have facilities specifically designed for a diagnostic laboratory and because we get to be physically closer to many of the ISU faculty with whom we work closely. In the meantime we are doing a lot of sorting, recycling, packing and cleaning!
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