Plant and Insect Diagnostic Clinic Update - July 2, 2008

Diseases and Disorders


  • We have received several samples of ornamental roses with rose rosette disease (HHPN July 2006). Symptoms include proliferation of new shoots; red discoloration and distortion of shoots; distortion and discoloration of leaves. Although this disease is presumed to be caused by a virus, this has never been proven, so there is no way to confirm a diagnosis. Rose rosette disease is transmitted from plant to plant by tiny eriophyid mites.

    Infected plants cannot be cured and should be removed. Bag the plants and remove them completely from the area.


  • Now is the time of year to expect to see dobsonflies, one of the largest insects in Iowa. The usual description of dobsonflies includes the words, "huge," "gray," "wrinkled," and "big pincers." The eastern dobsonfly, Corydalus cornutus, is found throughout the eastern half of the United States, including all of Iowa. See the photo below and HHPN July 25, 2007 for more details. You can also learn more about dobsonflies at BugGuide.
  • Millipedes are migrating by the millions. These beneficial recyclers live in damp areas such as under mulch, dead leaves and debris where they feed on decaying organic matter. But on warm, damp nights they migrate long distances and get into the house or garage by accident. They are harmless but annoying. The usual management is to seal cracks and gaps where they get in. Apply an insecticide residual barrier as a last resort. Click here for more information.
  • Digital Insect Photography. We can identify many insects, (and some plants and plant diseases) with a picture sent to us as an email attachment. Send the message and insect image to Include basic information about the insect in your message, such as size, where, when, doing what, how many, why do you want to know. In the dobsonfly photo below, please note the excellent use of a size reference, an important feature when sending digital photos for diagnosis.

 Dobsonfly female.
Dobsonfly female.


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