Fungus on my 60 year old crabapple tree leaves - Ask Extension
Each year I get some leaf spot and shedding on my crabapple tree but this year it is like nothing I've ever seen, the spots are larger than normal and...
Knowledgebase
Fungus on my 60 year old crabapple tree leaves #880483
Asked August 07, 2024, 7:26 AM EDT
Each year I get some leaf spot and shedding on my crabapple tree but this year it is like nothing I've ever seen, the spots are larger than normal and now they have spike looking growth out of the spots. This tree is large and if I need to spray the entire tree, it will be quite a job but I'm not sure if it is too late to treat it this year especially since I don't know what I am dealing with, your assistance is appreciated. Additional note, I have had this tree professionally trimmed (hand saw) every other year for the past 35 years by the same person in November, it was just trimmed 11/2023. Thank you
Livingston County Michigan
Expert Response
This is a very common fungal disease called apple scab. As with all fungal diseases, its spores are spread by wind and splashing rain. Fungicide sprays are effective only if applied before the disease becomes evident, in other words...to prevent it before it occurs. Spraying now will not "cure" the affected leaves.
Apple scab makes the tree very unsightly, but it generally does not affect the health of the tree unless defoliation occurs for a few years in a row.
The apple scab fungus overwinters on fallen diseased leaves. So the most important thing you can do is to rake up and destroy the leaves that fall from your tree. Do no compost them! This will help prevent re-infection next season.
Please see the information in the links below for additional information about this disease:
https://extension.umn.edu/plant-diseases/apple-scab
https://ohioline.osu.edu/factsheet/plpath-fru-23
Apple scab makes the tree very unsightly, but it generally does not affect the health of the tree unless defoliation occurs for a few years in a row.
The apple scab fungus overwinters on fallen diseased leaves. So the most important thing you can do is to rake up and destroy the leaves that fall from your tree. Do no compost them! This will help prevent re-infection next season.
Please see the information in the links below for additional information about this disease:
https://extension.umn.edu/plant-diseases/apple-scab
https://ohioline.osu.edu/factsheet/plpath-fru-23
