How Tree Doctors Solve Common Tree Problems

How Tree Doctors Solve Common Tree Problems

A day in the life of a plant pathologist reveals how Davey's detectives determine tree care solutions.

My recent visit to the Davey Institute's diagnostics lab revealed more details about diagnosing sick trees and plants than I ever imagined existing.

The lab was much quieter than I anticipated. For a few minutes I was the only person in the room. While I waited for my personal tour guide to arrive, I observed a wide variety of plants in containers ranging in size and shape. As I continued leisurely weaving in and out between shelving units and storage bins, I noticed rows of shelves crammed with colorful, bound books with a variety of topics, from fungi to insect species.

Lab tops were speckled with microscopes prepped to inspect the petri dish samples Debbie Miller, senior diagnostician and plant pathologist, had collected that morning. When she entered the room to greet me, Miller opened the samples according to U.S. Department of Agriculture standards, in the bio-safety cabinet.

"Before we even get to this point of inspecting the actual samples we receive photos via email in order to see the kind of environment the sick trees and plants are in," Miller says. "Depending on what comes to us, usually I can immediately determine the disease or pathogen, or I have to do additional research. I always want to be 100 percent correct in my diagnosis. There are rare times I've encountered something I've never seen before."

crab apple leaf disease inspection
Plant Pathologist Debbie Miller inspects the leaf of a crab apple tree for common tree problems.


With a gleam in her eye, Miller motions me to come over to the microscope to observe a dying plant's leaf. I notice black speckles in various shapes and sizes. "Those are two different forms of apple scab fungus," she says. "One is the asexual form and the other is the sexual form."

Davey Institute lab microscope
Miller inspects four to 20 tree samples at the Davey Institute every day.

The lab receives plant material and tree samples from Davey offices across North America. Samples arrive in packaging according to USDA standards, which ensures pathogens do not escape and samples stay alive by the time they reach the Institute. Miller will inspect four to 20 samples every day, all while completing lengthy and informational reports to send back to the district managers who requested the inspections and tests. "Some of the samples take days, which can be very time-consuming," Miller explains. "After I diagnose them, I send my 'prescription' to managers to explain what the plant needs."

Her "prescription" includes observations and instructions to improve the plant's health--if it can, in fact, be saved. "When a prescription is written by the plant doctor, most of them are cultural--watering, fertilizing and, in the worst-case scenario, removal," Miller laments. "I hate when I have to prescribe removal

Davey Institute lab plant inspection
Miller inspects plant material for pests, diseases and other health problems.

because I love trees so much!"


Miller wraps up her day by storing the samples that weren't diagnosed in the refrigerator, putting plants on petri dishes that need cultured and making sure the microscopes are sterilized, turned off and have protective coverings placed on them.

"There can be long days, but I love every minute of it," Miller expresses. "It's a very detailed job, and it takes a certain amount of patience since the No. 1 most important thing to a diagnostician is observation. But it is an exciting job because every day there is a different mystery to solve."

Do you have a tree problem you wish a Davey scientist could help you diagnose? Fill out this simple contact form to schedule a free consultation with one of Davey's professionally trained arborists.

  • The Tree Doctor February 25, 2016 >Hi Marvin, Thanks so much for reaching out to Davey for help. We're sorry to hear that your trees have a fungus harming them. To save your trees, we recommend scheduling a free consultation with your local tree doctor in North Cincinnati. They'll be able to inspect your trees and recommend a diagnosis and treatment. Here's how to schedule a consultation: Also, if you want to do some sleuthing on your, here's an article on how to identify some common tree fungi that will be helpful to you: Thank you!
  • marvin powell February 25, 2016 >my trees have a fungus that is killing them.
  • lorraine forbes January 28, 2016 >Some of my Queen Palms branches/leaves are not growing all the way out of the neck of the palm. It almost looks like they are dying but continue with stunted leaves/branches.
  • WILLIAM WARREN December 29, 2015 >Have redwoods needles are brown.
  • Scott Donnelly December 18, 2015 >Huge blue spruce from bottom to top have dead branches. My neighbor spruce is totally dead and I'm hoping it's not to late to save this one.. Thanks
  • Brenda Farmer November 19, 2015 >I have a oak tree, I think it's a water oak it does not have thorns. I notice right before fall it started loosing it's leaves way early. Now it has lost almost all of them. It looks like some branches on one side of the tree have died. I won't know until spring again. I have noticed a fungus growing on some branches mostly the ones that look dead. What is wrong with my tree and what can I do to save it.
  • The Tree Doctor August 24, 2015 >Hi Lani, Thank you for reaching out to Davey on our blog. We appreciate your comment. Please read below for Technical Advisor Rex Bastian’s suggestions re: your tree: Best as I can tell from your photos, your tree looks to be one of the hybrid poplars. These trees are fast growers, but do tend to be susceptible to many foliar diseases. Not sure of your location, but many parts of the US experienced wet spring conditions, which favors development of these diseases. On poplar, they typically make the tree look less attractive than usual, and can result in many leaves dropping earlier than usual. While these diseases can commonly occur to some extent every year, they can be worse during years with rainier than normal conditions. The trees usually tolerate these diseases pretty well, but the loss of aesthetics can be troublesome. There is nothing to be done at this time of year. The tree would need to be sprayed with a labeled fungicide during the spring and early summer season several times to help protect the leaves from the disease. This tree looks small enough that you could probably treat it with a hose end sprayer designed for treating trees. These can be purchased at any garden center or big box store. A good garden center can also help you with selecting a proper fungicide to use. The dark centers where you made the pruning cuts could be from several factors. Best thing is to just leave them be. No need to cover with a pruning paint or wound dressing. If the tree is healthy, the cuts will close over with time (several years). Thank you!
  • Lani Macrae August 24, 2015 >I don't know what kind of tree I have. Approximately 3 years old. Leaves all became spotted this summer and when I trimmed off some low hanging branches, in every limb, there was a dark brown circle that is at the center of the limb. Can I send you some pictures?
  • The Tree Doctor August 19, 2015 >Hi Tom! Thank you for your comment. From what our technical advisors can see in the photos you provided, they suspect the root system issue is the primary problem. You mentioned you have seen symptoms for several years, which suggests a chronic issue is affecting the tree over time. It looks like the tree is somewhat tufted in appearance, which suggests the growth increments are shortening. It also suggests the tree is having issues moving water and nutrients from the soil into the crown. We may be dealing with girdling roots out of sight, below the soil line, or with a root system that has been negatively impacted by the extreme environmental conditions we have experienced over the past several years. We see what looks like a brick ring around the base of the tree, but we cannot tell if the tree is in a well or not. That would suggest a grade change around the tree, but the photo is not clear enough for us to determine for sure. We would suggest having a certified arborist look at the tree to identify any potential issues that may be affecting the tree below grade. Options may be available to address those conditions, depending on what can be identified onsite. Thanks again!
  • Tom McGonigle August 1, 2015 >My wife and I have a 30 year old maple tree in our back yard that has been showing signs of stress. The leaves are small and some of the branches are dying. It has been showing signs of this for about 3 years but this year seems worse. Do you have any recommendations or is it too late?
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