We have had long, cool, damp Springs and the wettest May in history for 3 years in a row now in the Chicago area. Those are prime conditions for tree ‘issues’ to flourish. There are all types of fungus, leaf blights and winter damage occurring right now, causing leaves to blemish, yellow and fall from a wide array of trees and shrubs. Also, some green leaves will start falling soon.
Green Leaves Falling
We mention this almost every year. A fungal issue called Anthracnose causes stems on leaves to weaken and then fall. This can be pretty heavy at times. Its favorite target seems to be Ash, Maple, Oak and Hickory but can affect other trees as well. Don’t worry about this. It doesn’t really hurt the tree and it’s not really controllable anyway.
Yellow Leaves Falling
This yellowing leaf drop is due to ‘Frogeye Fungus’, which is different from Apple Scab. We have never treated for Frogeye in the past as its presence has been very sporadic over the years. The products we use for Apple Scab obviously won’t prevent Frogeye or this tree shown below wouldn’t have contracted this fungus. It is important to note that Frogeye isn’t as debilitating to Crabs as Apple Scab.
There are over 100 different varieties of Crab Apple trees and only a few are susceptible to Frogeye. In the past, leaf drop due to Frogeye has occurred over a period of a few weeks. The tree thins out a bit but re-foliates as the Summer progresses, whereas with Apple Scab, the tree defoliates, often almost completely, and stays that way from July through October. If your Crab Apple is exhibiting these symptoms we understand that it’s frustrating treating for one fungus and then have a different fungus come up unexpectedly. There are no fungicidal products that treat every conceivable fungus that might occur.
Sometimes, as is the case here, there is no way to predict certain issues until they happen. We don’t offer treatments for ‘what-if’s’. We offer treatments for what we ‘know’ will be a yearly issue. It makes no sense to treat year after year for something you might only experience once in 5 or 10 years.
There are many environmental factors that affect trees. We can treat and protect trees from the most serious issues, but you can’t treat for everything, nor should you.