Clinic Update: Late Summer Samples Submitted to the Diagnostic Clinic

We have received samples from a number of trees. Several of these samples have been from spruce. One sample had Rhizosphaera needlecast while other samples had significant spider mite infestations and were suffering from the impact of the drought. As a result, the needles were dropping from the trees. We also had scotch and white pine samples displaying a needle scorch and browning which we believe is also drought related. We have also had several oak samples. While we had oak samples that were positive for oak wilt earlier this summer, more recently all samples have been negative. It is important to keep in mind that only fresh samples from symptomatic branches which have not yet completely dried out and died can successfully be tested for oak wilt. Other oak samples have had several types of galls, oak leaf skeletonizer damage and spider mite infestations. We received another sample from a silver maple with anthracnose. We have been able to isolate the fireblight bacteria from some of the Callery pear samples we have received this summer and confirmed the presence of fireblight in these trees.

We have received a few shrub and perennial samples as well. Many of these shrubs have probably been severely stressed by the drought, however some of our samples may also be the result of overwatering to compensate for the hot, dry weather. We had a hydrangea sample with Phytophthora crown and root rot. Some euonymus samples had severe spider mite infestations. Rose samples had symptoms of rose rosette virus and powdery mildew. We also had an arborvitae with Armillaria root rot. A chrysanthemum sample had Rhizoctonia stem and root rot and a hosta had Alternaria leafspot. Other sample submissions were completely dead branches. The problem with these shrubs may have been with the crown and root system, and we will be unable to make a good diagnosis without seeing material from these areas and before the plant has completely died.

We have continued to receive fruit samples as well. A number of these samples have been from blueberries. In some cases, these plants appear to have been suffering from drought stress. We had an apple sample with insect borer damage. However, without finding the insect, it can be very difficult to confirm the identity of the insect responsible. Blackberry and watermelon samples were submitted with severe spider mite infestations. A kiwi sample was submitted with a leaf scorch we believe is likely due to environmental extremes this summer.

We have had fewer vegetable submissions recently, however we have had tomatoes with herbicide drift issues and Fusarium crown and root rot.

We have had a number of insect and other arthropod submissions including the following from inside buildings: brown recluse spiders, cellar spiders, Dermanyssid mites, cat flea larvae, red flower beetle, sawtoothed grain beetle, springtails, square necked grain beetle, and yellowjacket wasps. From outdoor sites, we have received the ash-grey blister beetle, digger wasp, and soldier beetle.

We welcome your sample submissions including plant problem diagnosis, and plant, weed, or insect identification. Please refer to the sample submission section of our website at http://soilplantlab.missouri.edu/plant/index.htm or call us at 573-882-3019 for more information on sample submission.

Simeon Wright
Plant Diagnostic Clinic
573-882-3019