Plant and Insect Diagnostic Clinic Update - February 20, 2008

  • We receive samples of plants from greenhouses this time of year. Most often, problems on greenhouse plants (and indoor houseplants) are caused by factors other than infectious diseases, such as improper pH, too much or too little fertilizer, imbalanced nutrients, or temperature problems. This oxalis (shamrock) plant has crinkled, mottled leaves due to cold growing temperatures.
    Oxalis

    Oxalis

  • Dothistroma needle blight is commonly found on Austrian and ponderosa pines, causing spotting and browning of needles. Although infection occurs in the spring, symptoms are visible year-round. See this article for more information.
  • We continue to receive spruce samples that appear to have "sudden needle drop"; see this article for information.
  • We received a sample of a silverfish, these insects can survive in homes and can occasionally be a pest. However, populations do not often get large enough that they cause damage.
  • Powderpost beetles were also sent in. We more often encounter the damage from these beetles, and rarely get to see the actual insect. Powderpost beetles leave round holes in wood and fine powder-like sawdust.
Category: 

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 February 20, 2008. The information contained within may not be the most current and accurate depending on when it is accessed.