Encyclopedia Article
Below are the common problems PIDC diagnosed in 2019 that where showcased in the hands-on workshop Diagnosing Health Problems of Woody Plants at the Shade Tree Short Course 2020.
To learn the term uses to describe symptoms and signs see our glossary
| Tree(s) | Symptoms observed | Signs present (visible)? (Y/N) | Notes | |||
| Oak Cottonwood | Branches (terminlal) in the ground, not cut clean separation (not chew) | N | Nature of the problem: | Abiotic | ||
| Diagnosis: | Cladaptosis | |||||
| Management: | Promote healthy plants, reduce stress, avoid site impacts | |||||
| Various, euonymus | Dieback. trees & shrubs that were ok in fall 2018, had symptoms in the spring 2019 | N | Nature of the problem: | Abiotic | ||
| Diagnosis: | Winter damage/ cold injury | |||||
| Management: | Proper plant section for hardiness | |||||
| Oak | Dead tufts of leaves, slower twig growth, busshier look | Y, round scale insects on branch | Nature of the problem: | Insect | ||
| Diagnosis: | Kermes Scale | |||||
| Management: | No management for large trees recommended, Dormant oils can be used on smaller trees | |||||
| maple, lilac, many other woody plants | Chlorotic or dead leaves, early fall color, poor growth | Y, scale insects on branches and/or trunk | Nature of the problem: | Insect | ||
| Diagnosis: | Oyster shellscale | |||||
| Management: | Pruning out heavily infested branches. Insecticides targeting crawler stage. | |||||
| Various oaks | Leaf spots, tree crown thining form the bottom up, defoliation (leaf drop) | N, magnification in the lab need for confimation | Nature of the problem: | Disease | ||
| Diagnosis: | Tubakia leaf spot | |||||
| Management: | Promote tree health, see more at https://hortnews.extension.iastate.edu/tubakia-leaf-spot-oaks | |||||
| White pine | Burn, discolored needles, needle drop? | N | Nature of the problem: | Abiotic | ||
| Diagnosis: | Ice Melt (salt) damage | |||||
| Management: | Avoid planng white pine near road that will be treated prunning afected branches is nor recommended | |||||
| Many trees | Leaf distortion,sticky honeydew, sooty mold, ants on plant | Y, aphids on leaves | Nature of the problem: | Insect | ||
| Diagnosis: | Aphids | |||||
| Management: | Soap or oil based insecticides if warranted. No treatment large trees. | |||||
| Maple, apple, oat, others | Leaf discoloraiton, distorted growth, dead areas on leaves. | Y, small green leafhoppers that run fast | Nature of the problem: | Insect | ||
| Diagnosis: | Leaf hopper burn | |||||
| Management: | no long term damage expected in stablish, healthy trees | |||||
| Arbovitae, oak, and others | Distorted leaf growth | N | Nature of the problem: | Abiotic | ||
| Diagnosis: | Suspected chemical injury, herbicide like damage | |||||
| Management: | read and follow pesticide label, proper herbicide use. Consider alternatives weed managment in the landscape | |||||
| Liden and Maple | Dieback, deline over a long period of time (years) | N | Nature of the problem: | Abiotic | ||
| Diagnosis: | Stem gridling roots | |||||
| Management: | Prevention, proper planting practices, select quality tree stock, root inspection, correct planing depth etc. correction may be effective only in young trees | |||||
| Sycamore and others | Vein disoloration, dieback, withces broom alike | N, magnification in the lab need for confimation | Nature of the problem: | Disease | ||
| Diagnosis: | Sycamore anthracnose | |||||
| Management: | Promote health!!, see more at https://hortnews.extension.iastate.edu/anthracnose-shade-trees-0 | |||||
| Lilacs, rhododendrum, oaks | Leaf sport, scorth tip burn, blight | N, lab testing need for confimation | Nature of the problem (circle) | Disease | ||
| Diagnosis: | Ramorum blight/ sudden death oak | |||||
| Management: | monitor rododendrum purchased/installed in 2019 submit samples to PIDC if supected, remove positive plants inlcuding roots https://hortnews.extension.iastate.edu/2019/07/be-alert-diseased-rhodode... | |||||
| Spruce, arbovitae, locust, many others | Missing needles or leaves. Brown needles. | Y, bags hanging on the tree | Nature of the problem (circle) | Insect | ||
| Diagnosis: | Bagworm | |||||
| Management: | Hand removal in winter. Insecticides targeting smaller caterpillars. | |||||
| Oak, elms, catalpa and others | Scorched leaves, yellow boder in some hosts | N, lab testing need for confimation | Nature of the problem (circle) | Disease | ||
| Diagnosis: | Bacterial Leaf scorch | |||||
| Management: | monitor, test and remove positives plants https://hortnews.extension.iastate.edu/2015/09-11/scorch.htm | |||||
| Oak | Leaf scorched, leaf loss, wilt | Y, fungal mats under the back or dead red oaks in the spring (remove tree!!!) | Nature of the problem (circle) | Disease | ||
| Diagnosis: | Oak wilt | |||||
| Management: | monitor trees, submit sample to PIDC for test (sample cold cain to avoid false negatives) https://hortnews.extension.iastate.edu/oak-wilt | |||||
Last Reviewed:
February, 2020