White Oak Problem

Question: Hello, we had this white oak professionally planted in November 2022.  It has grown nicely in height since then (from about 7 feet to about 10 feet I'd guess) but has signs of distress in the leaves.  Can you help us understand what the issue is?  We have watered it regularly when first planted and once it started budding out.  Thank you.

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 June 26, 2023, 3:15 PM EDT
response: The marginal (leaf-edge) browning could be from soil moisture stress (too much or too little) or some other environmental stressor; we can't rule out a disease but it's less likely given the type of symptoms. The small amount of skeletonization we see on a branch tip in the third photo may be from sawfly larvae or possibly young caterpillars but they are not going to cause any significant damage and do not need treatment.  With regards to watering, you mentioned having watered regularly, but how often and how much water was applied might be unintentionally over- or under-watering the roots. We recommend that plants be monitored by feeling the soil about six inches deep and watering only when it's becoming somewhat dry to the touch at that depth. (If damp at that depth when checked, the plant probably doesn't need water.) How much water to apply each irrigation session depends on the root ball size and soil drainage but might average around ten gallons for a tree this size. (Hard to judge...a tree-watering bag often holds about 20 gallons that it slowly drips into the root ball, for example.)  We can't quite see the trunk base, but if the lawn grows up to the trunk, we suggest it be removed for at least a foot or two encircling the trunk and mulch put down instead, taking care to not have the mulch contacting the trunk itself. This reduces the risk of mower/weed-whacker damage to the trunk (which can cause serious and untreatable injuries), exposure to lawn herbicides (we considered that a minor exposure to herbicide was responsible for the downward curling some leaves are showing), and reduces root competition with the lawn.  For now, just keep monitoring the roots for watering needs as our drought this year continues. (Recent rains helped, but we're still quite behind on rainfall for the year.) No treatments are needed at this point, and most new plants in the establishment period of their first year or two in the ground succumb to environmental stressors and not a pest or disease (root rot aside, since that begins by saturated conditions leading to opportunistic infection). If you see worsening or new symptoms, feel free to send us additional photos for assessment.  Miri

responder: The Question Asker Replied June 28, 2023, 10:45 PM EDT
response: Wow, what a thorough and helpful response!!  Thanks very much. We will start checking the moisture level in soil.  (The tree is mulched and we haven't used any herbicides so that shouldn't be an issue.)I am feeling particularly attached to this tree (and the bald cypress we planted at the same time, under Prince George's rebate program) so am grateful to have your advice.  And will check back if we need to.Thank you again,Cheryl On Mon, Jun 26, 2023, 3:15 PM Ask Extension <<personal data hidden>> wrote:

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 June 29, 2023, 9:14 AM EDT
response: You're welcome!

responder: The Question Asker Replied July 31, 2023, 10:03 PM EDT
response: And a few more it wouldn't let me send first time

responder: The Question Asker Replied July 31, 2023, 10:03 PM EDT
response: Hello, I'm back with some more photos and I'm quite concerned (I will be heart broken, planting this tree made me so happy).   I think they're something wrong - look at the trunk - but I tried to capture the whole tree and the leaves too.

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 August 01, 2023, 3:59 PM EDT
response: Hi Cheryl,  Most of the photos seem to be showing the same damage we addressed earlier: sawfly or some other insect chewing causing the "skeletonization" of that clump of leaves, plus either some environmental stress or perhaps a mild anthracnose fungal infection causing leaf-edge browning and some curling on the foliage. Leaves cannot heal from damage, even if the cause of that damage has since been resolved, so the tree won't look much different until it leafs-out again next year. That's ok, as long as it doesn't worsen considerably. Many insects chew on oak foliage, which is why they're so important to our local ecosystem, so a different set of chewing damage could potentially appear between now and autumn leaf drop. However, those insects will not harm the tree's long-term health and do not need treatment, especially since the pesticide that may be needed in that situation risks harming other organisms. The same is true for fungal infections: they are not curable with fungicide treatment, but those causing leaf spots or minor "burn" of leaf edges rarely threaten the tree's health nor would they need treatment (even if a fungicide would work to prevent disease spread, which they don't always).  As you indicated, the trunk damage pictured here is more concerning, since it looks like it penetrates beyond just the outer bark. We can't tell what created it or when, though it doesn't look super fresh, but the culprit is likely either lawn equipment or wild animals since an infection or insect tunneling under bark doesn't cause those scrape-like injuries. If wild animals, it looks too low to be deer antler rubbing (from last autumn in that case, since that hasn't happened yet this year) but could have been squirrels removing bark for consumption or nesting, or perhaps even the beginnings of woodpecker exploratory pecks if wood-boring insects are present.  Nothing can be done to treat this injury, nor should it be painted/coated with anything since that can hamper the wound-closure process, but keep an eye on the tree for a change in canopy health (beyond the minor symptoms shown here, which are unrelated). If deer visit the yard, it would be prudent to protect the trunk from antler rubbing this coming autumn by putting up a "cage" or wire-fencing barrier encircling the trunk. Prefab trunk wraps exist too (often plastic), but anything that allows for trunk growth (in girth) over time and provides good air circulation so the material doesn't trap moisture against the bark should be fine to try.  Sometimes trees can overcome this type of damage and sometimes they succumb, since there are many variables that can go into survival or weakening based on the degree of damage or what pest/disease problems were involved. (Narrowing-down a diagnosis is difficult without splitting the trunk open to look for other clues, which would be a post-mortem in that case, so naturally that's a last resort to investigate if the tree declines too much to keep in the future. Tree wound closure takes time, but it can happen if the plant is otherwise healthy and if no further damage occurs before it can be sealed-off, so just give the oak time and see how it fares.  Miri

responder: The Question Asker Replied August 01, 2023, 5:51 PM EDT
response: Thank you so much.   FWIW, this tree is in our fenced backyard so no deer.  I'd guess it is small animal damage from what I see, out of the options you mentioned. So we will put a wrap on it that allows it to breathe but hopefully keeps it from being further damaged.  And watch and see.  Bummed but at least a little hopeful now. Thank you.  (Also, okay to post if useful.)

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 August 02, 2023, 10:01 AM EDT
response: You're welcome.

responder: The Question Asker Replied August 06, 2023, 1:04 PM EDT
response: So FYI, I think we have root rot - these mushrooms just appeared. Will get our arborist to come out and see what needs to be done.  Thank you for your help along the way.   On Wed, Aug 2, 2023 at 10:01 AM Ask Extension <<personal data hidden>> wrote:

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 August 07, 2023, 9:27 AM EDT
response: Root rot pathogens do not create mushrooms that look like this, so this is a different fungus. They might indicate wood decay, but we don't think the root system of the tree is extensive enough at that age to support that much growth. They might simply be decay fungi harmlessly breaking-down the mulch instead. We can consult with our plant pathologist if you wish, though if they are a pathogen infecting the tree, unfortunately nothing can be done to treat/cure it. Consulting a certified arborist is certainly a good idea, though, and perhaps they can make a more fine-tuned diagnosis based on what they can assess in person.  Miri

responder: The Question Asker Replied August 28, 2023, 7:37 PM EDT
response: Thanks much for this response! Somehow I missed it earlier. The good news is that the mushrooms went away pretty quickly after they appeared, so we will consult with our arborist if needed. Thank you again for your help.On Mon, Aug 7, 2023, 9:28 AM Ask Extension <<personal data hidden>> wrote:

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 August 29, 2023, 9:23 AM EDT
response: You're welcome.