​​​Lauri A. Lutes and Jay W. Pscheidt

Dept. of Botany & Plant Pathology,
​Oregon State University, Corvallis, OR​

   July 16  ​

 Dr. Martinez,

 A field rep sent me an ima​​ge of some cherry leaves   with strange symptoms when they were out in the field the   other day. Have you ever seen this before? Any idea of what   could be causing this?

 - Morgan

 Here is a close-up:


Dr. Jennifer Martinez is an experienced Extension Plant Pathologist at Pacifica University in Oregon. One day in early June, a local extension agent, Morgan Khan, from the Mid-Columbia region – a prominent tree fruit production region along the Columbia River in north-central Oregon – emailed Dr. Martinez regarding some reports of odd-looking leaves from a sweet cherry orchard:

Dr. Martinez examines the images but knows she cannot make a proper diagnosis without obtaining more information.


  • Based on what you know about plant disease diagnosis, what questions would be useful for Dr. Martinez to ask? What resources do you have available to you to help solve this problem?

Fortunately, Dr. Martinez was able to contact the grower directly to obtain more information. Here is a transcript of their phone conversation:

JM: Hey Bailey! This is Dr. Martinez, Extension Plant Pathologist at Pacifica University. Morgan told me you’re having some problems with your cherries.

BW: Hi, Dr. Martinez! Thanks for calling. Yeah, I have some leaves that look really strange on the underside. Have you ever seen that before?

JM: Morgan sent me your image, and I agree, they do not look healthy. I see the ridges on the underside of the leaf. This is actually a symptom we call enation.

BW: Enation? Hmm. So, you know what it is then? Can you get rid of it?

JM: Well, before I jump to any conclusions, I’d like to get a little more information from you. What kind of cherry trees are these anyway?

BW: ‘Bing’ on ‘Mazzard’.

JM: Ok, so that’s a ‘Bing’ scion on a ‘Mazzard’ rootstock. And how old are they?

BW: They were grafted about 12 years ago.

JM: And Morgan told me you’re in The Dalles, correct?

BW: Yea, this orchard is off Dry Hollow.

JM: Is this problem something new that you have noticed?

BW: Well, I’d say I started noticing these trees last spring. I just haven’t had time to worry about it until now.

JM: I completely understand. So, would you say you found these deformed leaves all over the tree? Only on one tree? Half of the trees in the orchard?

BW: Oh, I don’t know, just noticed them on a few branches in one corner of an orchard block – maybe on 4 to 5 trees? I haven’t walked the whole orchard yet. I’m waiting for you to tell me if I need to worry about it first.

JM: Well, that’s what we are here for. So, this corner of the orchard, is it a particularly low or high spot in the orchard? Is the ground flat? Or is there anything different about that area?

BW: This orchard is terraced and these are on the high ground.

JM: What type of irrigation do you have? Overhead sprinklers? Micro sprinklers? Are there any wind fans nearby? I’m just trying to get a mental image of the area.

BW: We have a micro sprinkler system. No frost fans. Oh, and there is a power line – cuts right through the block.

JM: Alright. Well, thanks for that information. What I would like to do is get a sample from you to do some testing. Do you know if Alex will be around today?

BW: I think Alex was planning to stop by sometime today.

JM: Great. I will get in touch and have them collect about 20 leaves with the enation symptoms and some from a nearby tree of the same cultivar that isn’t showing symptoms. These can then be shipped in a plastic bag to the university.

BW: Sounds like a plan. Thanks for your help.  

JM: Great. Well, I look forward to working with the sample. Thanks for taking the time to talk with me today. We will be in touch.

BW: No problem. I’m looking forward to your results. Talk to you soon.


  • Based on Dr. Martinez’s conversation with the grower, is there any information that is still missing or confusing?
  • Would you have asked different questions or in a different way?
  • Does any of the information seem irrelevant?
  • ​Why might Dr. Martinez have wanted a sample of leaves from a tree that appears to be healthy, as well as a tree that is displaying symptoms?

Dr. Martinez is now feeling confident that she has enough information to begin the diagnostic process.


Use the following prompts and the Pacific Northwest Plant Disease Management Handbook to work alongside Dr. Martinez as she diagnoses this disease problem.

IMPORTANT: When searching the online handbook, type in search terms (e.g. cherry enation) into the “search all handbooks” bar, not the “quick find” bar in the middle of the page. See Background Inf​​​ormation section for more details about each step.

  1. Identify the host. (Common/Latin name)
  2. Describe symptoms and signs.​
  3. Describe the damage pattern. (In the community (e.g. orchard, field, section of landscaping), on individual plant, AND on individual plant part)
  4. Identify if there is evidence of damage spread. (Date of appearance, year-to-year changes)
  5. Identify the cultural or site conditions. (When, where, how was sample collected)
  6. Determine possible diagnosis. (Common name, scientific name of disease)
  7. Indicate level of certainty of identification. (Certain, most likely, tentative)
  8. Identify other possible causes of the symptoms.
  9. Describe what you would do to confirm the diagnosis.
  10. Determine possible control measures.

​​Get the Answers to these Questions​