My Holly bushes-The Royal Family have blank spots on some leaves followed by brown leaves that are dead and falling off branches. Looks like some type of fungus. I have went to various garden stores but not sure what fungacide to buy. Please advise.
Livingston County Michigan
Thank you for using the Ask an Expert service. Is there any way that you can take and upload 3 pictures of your holly bushes and the problem that you are referring to? A Zoomed-out picture of the holly bushes and surrounding area, and a couple close-up photos of the issue would be ideal. It's very hard to diagnose the issue without photos.
You should know what the specific disease is before you treat for it. The pesticide (ex. fungicide) label should indicate that the product is approved for use on the specific plant (holly) or plant group and for the specific disease issue that you have. Both of these things should be on the label.
There is also the possibility that it's not a disease issue, in which case you would not want to spray a fungicide.
If you'd like you can mail or bring a sample (like a few pieces of branches with affected leaves) to MSU Plant and Pest Diagnostic Services in East Lansing. Plant sample assessment is $20. Visit the website https://pestid.msu.edu/ for more information.
Please let me know if you have further questions!
Pictures of Holly bush question sent by email@example.com
Thanks for the photos. I'm going to have to look into this in the next few days. Could you send me a closer photo of the spots in the bottom center of the first photo? (The zoomed-out one). The spots I'd like to see closer have thick dark margins and tan centers and are on otherwise green leaves. You are right, it looks like it might be fungal.
Also, have you ever gotten a soil test around your hollies?
I have soil test kit.
Will send soil sample to MSU.
Thank you for the extra photos. I still cannot say for sure what is causing the spots on your hollies, i.e. it is not one of the few very visually obvious plant problems. However, leaf spots often do not severely impact the health of trees and shrubs, unless the infestation is particularly intense. I sent your photos to the plant pathologist at the MSU Plant and Pest Diagnostic Services (https://pestid.msu.edu/) and she suggested that you just stick with trying an acid based fertilizer and avoiding overhead watering, which can exacerbate fungal foliar disease issues, rather than applying a fungicide. The results of the soil test could help you decide how best to treat the soil. Doing things to maintain plant health like proper watering and fertilization is key in helping mitigate the impacts of potential plant disease.
Here are a couple of articles on holly and fungal leaf spots:
"Holly Leaf Spot" article from U. Mass Extension: https://ag.umass.edu/landscape/fact-sheets/holly-leaf-spot
"Fungal Leaf Spots - Shrubs" from U. of Maryland Extension
Since you did start by asking about fungicides, I will make a few more notes about that. Here is a relevant fact sheet:
"Homeowner's Guide to Fungicides" from the University of Kentucky:
An example of a protective fungicide that can be used by home gardeners is chlorothalonil. Chlorothalonil is the name of the active fungicide ingredient, and this can be found in products of different brand names. To give you an example of what needs to be found on the label, I looked at the label of the Ortho Garden Disease Control product. I am not endorsing this product, it just happens to have the active ingredient chlorothalonil. On page 13 of the pdf version of the label, I did find that this product can be used on holly. However, it is only labeled for use against Rhizoctonia Web Blight. I doubt this is what you have, since that disease occurs in hot, humid conditions, and it's been a cool, wet spring.
The above fungicide information would be for future questions about fungicides, since I've already said that the plant pathologist did not suggest spraying your hollies with fungicides.
Hope this information has helped! Please let me know if you have further questions.