Crab Apple Trees – Fungus

We mentioned that we expect fungal issues to be extensive this year in the Western suburbs. We are certain of that. For those of you whose Crab Apples we treat for Apple Scab, we know you will be happy with your decision to treat your trees. You will realize just how glad as the Summer progresses and you see other area Crabs missing 70% to 90% of their leaves in July, August, September and October.

Keep in mind though that a new fungus hit the area in the past few years called ‘Frogeye’ Fungus. This fungus is different and not nearly as debilitating as Apple Scab. It may create bright yellow spots on the leaves initially and the tree may then drop some bright yellow leaves onto your lawn. This situation too will last a few weeks and then stop. This occurrence happens early enough in the Summer that the trees will still have a chance to re-foliate. It is not anywhere near as harmful as Apple Scab which creates dark brown and black lesions on the leaves. Our Apple Scab products are not labeled for Frogeye. There is a limit to how many products we can mix together and there is no single product that controls every potential fungus that is out there. We focus primarily on Apple Scab which does the most harm by far.


Quite often we see trees or shrubs with limbs tied together with rope or wire. Tying with rope or wire should only be considered a temporary fix (a month or so) until you can perform what we suggest below.

We will see trees and bushes tied with rope or wire that homeowners then forget to remove. Over time it will cut into the branching and ends up killing the plant they were trying to save.

tree cable with eyeboltsThis photo shows the correct way to draw limbs together and secure them. It is far better to actually sink eyebolts directly into the limbs and wire the eyebolts together. In doing so they can be left there indefinitely for future support. This photo example was performed on Arborvitae.

For tree limbs, you can actually drill all the way through the limbs and put a washer and nut on the outside end of the eyebolts or even send a threaded rod (available at hardware stores) through the branches and connect the ends with washers and nuts.  For bigger trees with big splits, hire a reputable tree company that can offer ‘cable bracing’ or ‘bolting.

tree cablingThis photo is of a 250 year old Oak on our owner’s property. The 20 inch diameter limb section on the left split vertically over 12 feet down the trunk. The open air gap between the branch section and the trunk was 8 inches wide and the slightest wind kept widening the split. The tree was ‘bolted’ with two half inch diameter hardened lengths of threaded steel rods (red arrows). The branch was ‘drawn’ back toward the trunk during the process and has now held for 30 years, saving the tree.

If you need bushes or small trees secured you will have to find someone handy in your family to perform the work. If you have a large tree you can call our office for a recommendation of a company who can help you.  We hope you found this educational and helpful!


Please see the photos below. These leaf depictions are a result of Anthracnose Fungus which manifests itself in a few different ways.

These are Maple leaves. This situation may or may not be evident just yet but a lot of trees will display similar damage over the coming month. Maple, Oak and a few other tree varieties can get Anthracnose. The wetter the Spring, the more issues there will be with all varieties of fungus and we all know just how wet this Spring has been in the Chicago suburbs.

Anthracnose is an airborne spore which blows onto susceptible trees and even some shrubs. We do ‘not’ recommend treating for this particular fungus because it is ‘not’ a yearly occurrence like it is with Apple Scab Fungus on Crabs or more recently, Rhizosphaera Needle Cast Fungus on Spruce trees. The extent to which Anthracnose Fungus will affect trees is an unknown in any given year. We must be ‘proactive’ in treating for any fungus and once a fungal condition begins to show visible signs, it is already too late to treat for that season. Why spend money on a treatment that is only an issue on occasion?

This next photo shows seemingly healthy green Ash leaves strewn about on a brick patio.This situation is also a result of Anthracnose Fungus. In the case of Ash trees, Anthracnose attacks leaf stems causing them to weaken and disconnect from the branch. As a result, individual leaves or clusters of leaves fall to the ground. Other than being unsightly, this condition should stop occurring after a few weeks. In a bad year, an Ash can lose up to 75% of its leaves but the tree will re-foliate as the Summer progresses. Your tree will not die due to this condition.