Plant and Insect Diagnostic Clinic Update – July 15, 2019

The following are highlights and updates about sample submissions for our different services (identification or Plant problem diagnosis 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 diagnosis  (with links to articles)

Host Category Plant Identification or Diagnosis
Broadleaf trees Red Maple  Suspected transplant stress, trunk cracks
Broadleaf trees Poplar (Hybrids)

Marssonina leaf spot on aspen 

Marssonina Leaf Spot, caused by Marssonina spp (M. populi  and M. brunnea)
Evidence (signs) of the fungal pathogens Marssonina spp (M. populi and M. brunnea) that cause Marssonina Leaf Spot in poplar. Photo credit: Lina Rodriguez Salamanca, Iowa State University Plant & Insect Diagnostic Clinic

Broadleaf trees

Star Magnolia

Magnolia Scale

Broadleaf trees Serviceberry Sawfly damage Pear Sawfly or Pearslug
Broadleaf trees London Planetree Click beetles
Broadleaf trees Silver Maple

Maple Tar Spot, Negative for Verticillium wilt

Broadleaf trees Pear (Ornamental)

Pear leaf blister mite

Broadleaf trees Dogwood Cercospora (Fungal) leaf spot
Broadleaf trees Red Oaks Oak anthracnose  Anthracnose on shade trees
Broadleaf trees

White Oak

Suspected Two line chestnut borer, Tree decline

Broadleaf trees Ohio Buckeye Fungal leaf spot (anthracnose), Physiological leaf scorch
Coniferous trees Arborvitae Phyllosticta needle blight *** NEW ENCYCLOPEDIA ARTICLE***
Coniferous trees Spruce Abiotic disorder-Suspected environmental injury
Fruit Cherry Cherry fruit fly Fruit, Vinegar, and Pomace Flies
Fruit Raspberry Decline, virus
Fruit Japanese Pear Fire Blight
Fruit Common Apple Apple scab
Fruit Common Apple Suspected injury Preventing Herbicide Injury in the Landscape
Fruit Hops Hops downy mildew 
Signs of Pseudopernospora humili
Signs of Pseudopernospora humili

Perennials and Annuals Burning Bush Potential injury Preventing Herbicide Injury in the Landscape
Perennials and Annuals Forsythia Suspected crown and root rot
Perennials and Annuals Pinnate Prairie Coneflower Septoria leaf spot
Perennials and Annuals Buttonbush Eriophyid mite galls Insect Galls on Trees and Shrubs
Perennials and Annuals Goldenrod Gall midge, fungal leaf spot
Turf Kentucky Bluegrass Red threat, Ascochyta leaf blight, Summer patch, brown patch
Vegetables Tomato Tomato Spotted Wilt Virus TSWV, White mold (Sclerotinia), Alternaria blight and canker see Tomato Diseases and Disorders
Pathogens Cabbage Alternaria leaf spot
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Authors: 

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  (clinic.ipm.iastate.edu), a member of the National Plant Diagnostic Network (NPDN, ...

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 July 16, 2019. The information contained within may not be the most current and accurate depending on when it is accessed.