Issue 12, September 22, 2021
August 2021 Plant Clinic Sample Summary
Summary of ornamental, fruit, and vegetable samples diagnosed August 2021.
The Plant Clinic remains open. We are currently operating with reduced staff and are only in the lab as needed for diagnostics and other lab work. We may not be able to answer or return phone calls in a timely manner though we are making every attempt to do so. You can also email us at plantclinic@illinois.edu.
Samples shipped via USPS, UPS, and FedEx are all arriving in a timely manner. We recommend shipping early in the week (Monday-Wednesday) and keeping the tracking number so we can trace the package if needed.
We are receiving more maple and oak samples. A bur oak sample from Lake Co. tested positive for Oak Wilt (http://hyg.ipm.illinois.edu/article.php?id=1163), a lethal oak disease. As a reminder, do not prune oak trees during the growing season!
We are seeing an increased number of oak samples with various insect pests, including kermes scale and jumping oak gall. While jumping oak gall is usually not considered a threat to overall healthy trees, heavy infestations especially on white oaks can cause browning and defoliation: https://www.canr.msu.edu/news/jumping_oak_gall_causing_damage_to_white_oak
We’ve had a number of ornamental samples submitted displaying pot-bound roots. These plants were planted into landscape beds but the rootball does not appear to have been separated or opened up before planting. These plants did not establish well into the landscape and once the hot, dry weather started their poor root system was unable to take up sufficient water and the plants began to suffer. This is a good reminder to disrupt root balls when planting, everything from woody perennials to herbaceous annuals!
We’re also starting to see environmental scorch symptoms and symptoms characteristic of bacterial leaf scorch. We will be testing for bacterial leaf scorch later in the season (September and October). Samples can be submitted now and will be stored until we begin tests. For more information about bacterial leaf scorch, please see: http://hyg.ipm.illinois.edu/article.php?id=1029
| Host | Pathogens and/or Pests Confirmed (C) or Suspected (S) |
|---|---|
| Arborvitae | Phyllosticta needle blight (C), Phytophthora root rot (C) |
| Blackberry | Cane and leaf rust (C), spider mites (C) |
| Boxwood | Volutella blight (C), Boxwood leafminer (C), Boxwood spidermite (S), Boxwood psyllid (C), Environmental stress (S) |
| Catalpa | Anthracnose (C), Verticillium wilt (C) |
| Chrysanthemum | Fusarium canker (S), Fusarium wilt (S) |
| Crabapple | Fungal cankers (C), Environmental stress (S) |
| Cucurbits (pumpkin, squash) | Anthracnose (C), Angular leaf spot (C), Environmental stress (S) |
| Dahlia | Dickeya stem rot (S) |
| Dogwood | Mulberry whitefly (C), Transplant shock (S) |
| Garlic | Acarid mites (C) |
| Juniper | Kabatina needle blight (C) |
| Maple | Anthracnose (C), Phyllosticta leaf spot (C), Oystershell scale (C), Maple spider mite (C), Maple spindle gall mite (C), Fungal cankers (C), Lecanium scale (C), Bark/Ambrosia beetles (S), Environmental stress (S) |
| Oak | Oak wilt (C), Anthracnose (C), Leaf blister (C), Cristulariella leaf spot (C), Kermes scale (C), Jumping oak gall (C), Oak twig canker (C), Oak lace bug (C), Fugal cankers (C), Anthracnose (C), Environmental stress (S) |
| Pear | Entomosporium leaf spot (C) |
| Pine | Diplodia tip blight (C), Pestalotiopsis needle blight (C), Pine needle scale (C), Dothistroma needle blight (C), Environmental stress (S) |
| Privet | Rhizoctonia root rot (C) |
| Raspberry | Spur and Cane blight (C), Environmental stress (S) |
| Rudbeckia | Verticillium wilt (C) |
| Serviceberry | Environmental stress (S) |
| Spirea | Cylindrosporium leaf spot (C) |
| Spruce | Sudden Needle Drop (SNEED) (C), Pine needle scale (C), Rhizosphaera needle cast (C), Stigmina needle cast (C), Spruce spider mite (C), Sirococcus needle blight (C), Environmental stress (S) |
| Sunflower | Alternaria leaf spot (C) |
| Tomato | Cercospora leaf spot (C), Rhizoctonia crown and root rot (C) |
| Turf | Rhizoctonia crown and root rot (C), Anthracnose (C), Dense thatch layer (C) |
Author:
Diane Plewa