Plant and Insect Diagnostic Clinic Update – August 16, 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 CategoryPlantIdentification or Diagnosis
Coniferous treesSpruceStigmina needle cast, suspected environmental stress, fungal cankers
Scots PineDiplodia Tip Blight and Canker, suspected Pine wilt

Suspected environmental stress

Phyllosticta needle blight

Phomopsis tip blight

Broadleaf treesEastern RedbudTransplant stress, Poor Planting Practices and Post-planting Care
ornamental pearFire Blight
Ornamental prunusBlack Knot
Lilac Pseudocercospora Leaf Spot, Powdery Mildew
MagnoliaMagnolia Scale

Girdling roots 

maple on the right thin canopy
Maple on the right with a thinning canopy
maple girdling roots choking the tree
Upon close inspection girdling roots choking the maple tree.
Willow Willow anthracnose
Oak (various)

Bur Oak Blight, Anthracnose on shade trees,  

suspected wetwood or slime flux, Suspected Physiological scorch,

Bot twig canker, Tubakia leaf spot in Oaks, Oak decline

Japanese Beetle feeding damage

Fruit (small and tree)Apple Cedar-Apple Rust
Japanese Beetle feeding damage
Phoma leaf spot
Suspected chemical injury, phytoplasma or virus
pearPear rust and various fungal spots
StrawberryPhomopsis blight
Cherrysuspected decline

Fusarium basal rot, Stem and Bulb nematode,

Bulb mites, Purple blotch

KaleAlternaria leaf spot
MuskmelonAlternaria spot and leaf blight 
OnionSoft rot 
PepperCutworm damage, Secondary soft rot
TomatoBacterial canker, see Tomato Diseases and Disorders
Phytotoxicity suspected

Yellow shoulder 

Yellow Shoulder on Tomato Fruit
Yellow shoulder on tomato fruit
Leaf mold  
Suspected herbicide injury
Perennials and AnnualsSedumPythium root rot
Clematis wilt/ blight 

Clematis wilt/ blight  

Clematis blight cause by the fungal pathogen Phoma clematidina
Clematis blight and leaf spot cause by the fungal pathogen Phoma clematidina
Turf/LawnVarious grassesCurvularia blight, anthracnose

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