Weeping Cherry gone brown

Question: We're looking for help diagnosing the problem with our weeping cherry tree. It was planted about 5 or 6 years ago and had been doing fine.  A couple weeks ago the leaves started turning brown and now they all have.  We've noted a fair amount of sap draining from a split on one side of the trunk over the last number of months. And some signs of moles in the area.  But otherwise it has been a healthy tree. Any ideas on how to help this tree?

responder: Answered by the Home and Garden Information Center (HGIC), University of Maryland Extension. For timely gardening information and tips, subscribe to our Maryland Grows blog and quarterly newsletter. Follow us on Facebook, Instagram, and YouTube. Replied July 11, 2023, 5:26 PM EDT
response: Unfortunately with total canopy dieback like this, the tree is not salvageable. As to the cause, it's hard to determine since several factors can cause sap oozing (called "gummosis"), but wood-boring insects, a fungal or bacterial trunk infection, or general tree stress are all candidates. There are no insecticides that can treat wood-boring insects once they are inside the wood, and similarly no fungicide will manage an infection once it grows into the sapwood. If stress is the only culprit, root moisture is a common issue as cherries are sensitive to drought but even more intolerant of compacted and poorly-drained or wet soils.  If you replace the tree, you can check the planting depth before installation, looking for the location of the root flare on a new tree by gently removing any surface soil from around the trunk base until the flare is visible. It should sit just at the soil surface once the tree is placed into the planting hole and the soil backfilled. Often, nursery-grown trees have a flare that is buried by several inches by the time they are sold, which is not how they should be planted since this can exacerbate tree stress or cause decline years down the road. We can't quite tell if the cherry here was planted too deeply (it's quite common) but suspect it might have been given the appearance of the trunk base, even if that might not have contributed directly to its current condition.  Moles don't feed on tree roots or chew into bark, though voles can, especially in deeply-mulched areas or when winter snows are abundant (certainly not that in recent years). We don't see evidence of vole damage here, but when you pull up the tree, you can look for gnawed-off bark below the mulch/soil line.  Do you know if the root ball was loosened/disentangled when the tree was first planted? If not, this can hamper establishment and trees and shrubs sometimes appear to be growing normally for a time but a stressful event can push them over the limits of their tolerances if the roots never grow much beyond the original confines of the root ball. You can see if the roots expanded outwards from the trunk well when the tree is removed. If it's close to the original root ball size and shape, this would be something to address for a new tree.  Wood-boring insects often target trees under stress, even if that stress isn't yet evident to us, so they tend to be a secondary issue, even though they can kill a tree. Ornamental cherries are unfortunately vulnerable to an array of pests and diseases, which you can explore on our diagnostic page for this plant group. As such, despite being capable of long lives when thriving, they tend to be more short-lived (two or three decades, maybe) in home landscapes because of residual soil compaction and other challenges. To be fair, some of our local natives, like Redbud, can be similarly short-lived, but they at least provide more ecosystem benefits than non-native cherries. There are a number of trees you can choose from (including another cherry if you prefer) for a sunny site if it's well-drained, and just be aware that any tree can contract one or more problems if it's wounded, stressed, or otherwise not a great match for the site conditions. (Say, not a wet-tolerant species in an area close to a roof downspout outlet, as an example.) If you would like our feedback on options, we can offer some ideas, though the overall list of candidates is too long to include here.  For just about any tree you wish to (re)plant, early autumn is an excellent time to install them since the air is cooling, the soil is still warm for continued root growth for some time after planting, and the demands on the plant's canopy are minimal because foliage is about to shed for autumn.  Miri

responder: The Question Asker Replied July 13, 2023, 9:21 AM EDT
response: Miriam,Thank you very much for all the detailed information!  I'm sorry to hear the tree is likely not salvageable. I don't know how the root ball was treated when first installed. We'll have to take a look when we have the tree replaced.  Thanks again for the help,   Jonathan

responder: Answered by the Home and Garden Information Center (HGIC), University of Maryland Extension. For timely gardening information and tips, subscribe to our Maryland Grows blog and quarterly newsletter. Follow us on Facebook, Instagram, and YouTube. Replied July 13, 2023, 10:04 AM EDT
response: You're welcome.