Issue 14, October 22, 2021
September and October 2021 Plant Clinic Sample Summary
Summary of ornamental, fruit, and vegetable samples diagnosed September 1 through Oct. 15 at the University of Illinois Plant Clinic.
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. Tubakia leaf spot is showing up late in the season on oak trees; for more information about this disease, please see: http://hyg.ipm.illinois.edu/article.php?id=738
Two common insect pests associated with environmental stress, Kermes and Lecanium scale, have also been showing up more frequently than in the past. For more information about Lecanium scales, please see: http://hyg.ipm.illinois.edu/article.php?id=804 and for more information about Kermes scales, please see: http://hyg.ipm.illinois.edu/article.php?id=368 As in August, we’re seeing a lot of jumping oak gall. This is usually not considered a threat to overall healthy trees, though 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 tested 51 samples for bacterial leaf scorch (BLS) in September and will continue testing samples as they are submitted. Samples can be submitted now and will be tested in batches. For more information about bacterial leaf scorch, please see: http://hyg.ipm.illinois.edu/article.php?id=1029
The number of turf samples submitted has increased in the last month. The most common diagnoses has been with anthracnose basal rot, a difficult-to-control disease. For more information, please see: https://hortnews.extension.iastate.edu/2011/6-15/turfdisease.html and https://ag.umass.edu/turf/fact-sheets/anthracnose-foliar-blight-basal-rot. We’ve also found rust on a few samples.
As we get into the end of the growing season, remember to prepare your plants for winter! Carefully inspect any tender plants you plan to bring inside, both before and after you move them into your house. Be ready to treat pests that may appear, especially spider mites. Continue watering trees and shrubs if we hit a dry spell until the plants have completely shut down for the winter. Consider a barrier or insulation for plants that are prone to damage due to cold temperatures or exposure to drying winds. These tasks can help plants make it safely through the winter so they’re ready to grow next year!
| Host | Pathogens and/or Pests Confirmed (C) or Suspected (S) |
|---|---|
| Apple (domestic) | Apple black rot (C), Frogeye leaf spot (C), Apple scab (C) |
| Arborvitae | Phyllosticta needle blight (C), Environmental stress (S) |
| Boxwood | Macrophoma leaf spot (C), Volutella blight (C), Fusarium canker (C), Environmental stress (S) |
| Catalpa | Verticillium wilt (C) |
| Cockscomb (Celosia) | Environmental stress (S) |
| Chrysanthemum | Fusarium canker (C) |
| Crabapple | Apple scab (C) |
| Dogwood | Frogeye leaf spot (C) |
| Globe Amaranth | Rhizoctonia root rot (C) |
| Juniper | Kabatina needle blight (C), Phomopsis tip blight (C) |
| Maple | Anthracnose (C), Phyllosticta leaf spot (C), Maple spider mite (C), Fungal cankers (C), Lecanium scale (C), Environmental stress (S) |
| Oak | Oak wilt (C), Anthracnose (C), Bacterial leaf scorch (C), Cynipid gall wasp (C), Tubakia leaf spot (C), Powedry mildew (C), Cristulariella leaf spot (C), Kermes scale (C), Jumping oak gall (C), Fugal cankers (C), Anthracnose (C), Bur oak blight (S), Environmental stress (S), |
| Oxeye | White mold (C) |
| Pine | Environmental stress (S) |
| Rhododendron | Azalea bark scale (C), Environmental stress (S) |
| Spruce | Sudden Needle Drop (SNEED) (C), Pine needle scale (C), Rhizosphaera needle cast (C), Stigmina needle cast (C), Spruce bud scale (C), Spruce spider mite (S), Environmental stress (S) |
| Turf | Anthracnose (C), Biploaris leaf spot (C), Rust (C), Rhizoctonia root rot (C) |
| Yew | Cryptocline needle blight (C), Phyllosticta (C), Oedema (C), Environmental stress (S) |
Author:
Diane Plewa