Plant and Insect Diagnostic Clinic Update – November 13, 2017

The following are highlights and updates about samples 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.

The following are plant diseases and insect damage highlights of last month's sample submissions from fruit, vegetables, and ornamentals.  

Broadleaf Trees 

crown gall in raspberry plant
Symptoms of crown gall in a raspberry plant. note the yellow arrow point to the tumor or growth cause by the   bacterium A. tumefaciens

Red oak, Oak wilt, suspected physiological scorch

Bur Oak, Bur oak blight

White oak, Two lined chestnut borer  

Hickory, Hickory scab, mites, suspected decline

Crabapple, scab

Coniferous Trees

Pine, Dothistroma needle blight

Arborvitae, Suspected transplant/establishment issues, Bark beetle damage

Spruce, Rhizosphaera needle cast, Stigmina needle castSudden Needle DropSpruce spider mites,

Norway Spruce, Rhizosphaera needle cast,

Colorado Blue Spruce, Environmental Stress, Pine Needle Scale, Sudden Needle Drop

Crown gall close up
Crown gall close up

Perennials and Annuals

Ninebark, Rhizoctonia root rot

Dracaena, Bacterial leaf spot. To learn about management of bacterial disease on foliage plants, see this resource form University of Minnesota

Cape Primrose, INSV (Inpatients necrotic spot virus)


Tomato, spider mite damage

Swiss Chard, Pythium root rot

Garlic, Dry bulb mite

Fruit (small and tree fruit, including hops)

Raspberry, Crown gall

Apple, Sooty mold due to insect activity


Plant, mushroom, and insect identifications:

Mushroom Identification

spider mites in tomato leaves
Spider mites in tomato leaves. Note the red arrow point to the mite

Mycena sp., Lepiota sp. Lepiota mushrooms are one of the various fungi that may be present in lawns as fairy rings.

Plant Identification

Puncture vine (Tribulus terrestris). Puncture vine is typically found in sandy or compacted soils and disturbed sites. Common sites are along roadsides and railroad tracks, pastures, and waste areas. Puncture vine is not widespread in Iowa and is most often found in the southern half of the state.

Broadleaf plantain

Insect identifications

Termites are a serious structural pest.  It is important to correctly identify termites or their damage and work with a pest management company to treat them.

Six-spotted tiger beetles are commonly submitted as suspect emerald ash borers because they are iridescent green.  Luckily six-spotted tiger beetles are beneficial predators and will not harm trees.

Bed bugs are unfortunately a very frequent sample in the clinic.  



Lina Rodriguez Salamanca Extension Plant Pathologist and Diagnostician

Dr. Lina Rodriguez-Salamanca is a diagnostician and extension plant pathologist with the Iowa State University Plant and Insect Diagnostic Clinic  (, a member of the National Plant Diagnostic Network (NPDN, ...

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