Issue 3, May 19, 2021
First Quarter 2021 Plant Clinic Sample Summary
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; MWF are the best days to contact us due to staffing schedules. 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.
Boxwood samples the most common over the past few two months. One sample was diagnosed with boxwood blight, and this disease is still a concern especially in the northern part of the state. For more information about boxwood blight, please see: http://hyg.ipm.illinois.edu/article.php?id=869 and http://hyg.ipm.illinois.edu/article.php?id=1137.
We’re seeing a lot of needle blights and needle casts on fir, spruce, and pine; this is not uncommon in spring. Many of these diseases attack stressed plants, so reducing stress by selecting the correct plant for the space, not planting too deeply, pruning during dry weather, fertilizing appropriately, watering during periods of dryness, and mulching will all help reduce the severity of these diseases.
The table below summarizes the ornamental, fruit, and vegetable samples received January through April 2021.
| Host | Pathogens and/or Pests Confirmed (C) or Suspected (S) |
|---|---|
| Austrian Pine | Diplodia tip blight (C), Red band needle blight (C) |
| Boxwood | Boxwood Blight (C), Volutella blight (C), Fusarium canker (C), Macrophoma leaf spot (C), Boxwood leafminer (C), Boxwood psyllid (C), Boxwood spidermite (S), environmental stress (S) |
| Coleus | |
| Colorado Blue Spruce | Rhizosphaera needle cast (C), Stigmina needle blight (C), environmental stress (S) |
| Easter Lily | Rhizoctonia root rot (C) |
| Elm | Fungal canker (C) |
| Fir | Phyllosticta needle blight (C), Rhizosphaera needle cast (C), environmental stress (S) |
| Hibiscus | No pathogen found (C), environmental stress (S) |
| Holly | No pathogen found (C), environmental stress (S) |
| Inch Plant | Tobacco Mosaic Virus (C), Botrytis blight (C) |
| Kale | Rhizoctonia damping off (C), aphids (C) |
| Lavender | Phytophthora root rot (C) |
| Linden | Insect damage |
| Microgreens | Pythium root rot (C), fungus gnats (C), slime mold (C) |
| Oak | Oak bullet gall wasp (C), Fungal canker (C), Katydid damage (C) |
| Pachysandra | Volutella blight (C), Oystershell scale (C) |
| Pea | No pathogen found (C), environmental stress (S) |
| Serviceberry | Cicada egg-laying injury (C) |
| Tomato | Edema (C) |
Author:
Diane Plewa