Plant and Insect Diagnostic Clinic Update – June 8, 2018

The following are highlights and updates about sample submissions from fruit, vegetables, and ornamentals, and questions recently received in the Plant and Insect Diagnostic Clinic. Visit the PIDC's Facebook page for updates and more pictures. For more information on a particular disease or insect problem listed, follow the article cited.

Plant Problem Diagnoses  (with links to ISU Encyclopedia articles)

Broadleaf trees

Pear -  Fire blight, rust  

Green and red ash -  Emerald Ash Borer

Linden - sooty mold

Birch, linden, ash, red oak - abiotic: suspected chemical injury, see our article Preventing Herbicide Injury in the Landscape

Ash - anthracnose,  abiotic: leaf scorch  

Prunus - black knot

 fungal structures (signs) of Rhizoctonia solani causing Brown patch in turf grass
Fungal structures (signs) of Rhizoctonia solani causing Brown patch in turf grass

Coniferous trees

Spruce - Rhizosphaera needle cast, Stigmina needle cast, Spruce bud scale, Spruce needleminer, Edema -fir tree 

Pine - Suspected winter injury/stress

Arbovitae - Phyllosticta needle blight, suspected winter injury

Perennials and Annuals

Boxwood - Macrophoma leaf spot, winter injury - be on the look for boxwood blight

Turfgrass & lawn

Mixed species - Brown patch, various nematode (Lance, Ring, Stunt, Spiral)

Insect identification

larder beetle larvae are carrot-shaped
Larder beetle larvae are approximately 1/2 inch in length and characterized by two curved spines on the last body segment.

Lone star ticks, American dog tick (male)

Bird mites

Bed bugs

Odorous house ant, Midge, Clover mite, Humpbacked fly

Click beetle

Dermestid beetles - carpet beetles, larder beetles


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