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Bicolor Oak, could this be 'Oak Wilt'?

3 months ago

Earlier this spring, the buds breaking on this tree looked pretty green. After a week, the very small leaves didn't look good, and I thought that the buds had late frost damage. But it did look like some of the buds were expanding, though not like they should be with all the warm weather.


Lately, those leaves have been turning brown and shriveling up.

There are what looked like dormant buds but they've not advanced at all the last week.




The entire tree appears the same overall.

Any ideas?

Comments (33)

  • 3 months ago

    It could be, but those trees in the White Oak group have greater resistance. How old and big is this tree?

    BillMN-z4a thanked maackia
  • 3 months ago
    last modified: 3 months ago

    If it's oak wilt, it won't last long. To me, looks like frost damage, as my bicolor had, until leaves emerged from the secondary (backup) buds. One of my brother's white oaks died from oak wilt -- shown here while it was healthy.


    BillMN-z4a thanked bengz6westmd
  • 3 months ago

    Mine is 6 years old and about 12 ft. tall and I'm outside of the Oak wilt area designated by the MN-DNR. But the dormant buds look so dry, and the earlier 'green push' has ceased.

    I'll have to wait and see but even with sufficient rain and supplemental watering it appears dead.

  • 3 months ago

    Bill, I STILL have a few trees barely emerging from the freezes, particularly dawn redwood, osage orange and ginkgo. So don't give up yet. One year my shumard x something oak, which has always been vulnerable to freezes, didn't come back out until July, and then poorly.

    BillMN-z4a thanked bengz6westmd
  • 3 months ago

    IIRC, this is the tree you grew from an acorn of the Ground Zero tree? I'm sure it has special meaning to you. Keep it watered and give it time to try and recover. If it were me I'd leave it be for a good long while.

    BillMN-z4a thanked indianagardengirl
  • 3 months ago
    last modified: 3 months ago

    Thanks all!

    I was almost ready to yank it out and replace it with my extra Serbian spruce. It would look good there, but DW vetoed the idea. 🤣

    The tree acted like it was putting out new sprouts a week or two after the frost but suddenly started to wilt. All those little brown leaves were green a week or so ago and now they've turned brown too. And we've had perfect growing weather.

    But I can't transplant at this time anyways, so I can wait longer to see what it does.

    Everything else is all leafed out.

    Here's a sneak preview of what's to come later this season.

    6-5-2026: Acer Pseudosieboldianum: (Oak in question is in the left background. Picea meyeri, right).

    Apparently, no winter damage on this one. 6-12" of new growth.


    :-)

  • 3 months ago

    Hope the oak makes it

    BillMN-z4a thanked L Clark (zone 4 WY)
  • 2 months ago

    I noticed some buds growing on the lower two thirds of the trunk only.



  • 2 months ago

    Update: 6-17-2026:

    I think everything above the bottom of the low branches is dead.


    The highest new sprout is just below the lower branches and of course they're the smallest of them.

    Something I rarely do, a 'Scratch Test' on those lower branches appears they're dead.



    There's plenty of new shoots below these last two photos. So I suppose one option would be to cut the tree off just above those highest shoots and start those into a new main leader.

    I'm sure there's enough energy in those established roots that a new leader would grow pretty fast.


    But I'll have time to decide and give it more time to see what happens.

    The higher on the trunk the new leader starts from, the smaller the wound the sooner it would begin to look like a tree again.

    Replacement would be the other option.


  • 2 months ago
    last modified: 2 months ago

    It's not promising. However, I posted pics of my bur oak devastated by the late freezes sprouting out of the trunk (and so did my SW oak), but now the second-buds have sprouted on both and the trees are fully leafed-out, tho no flowers or acorns (I'm finding out freeze-damaged trees eventually leaf out, but no flowers or fruit). Don't THINK it's oak wilt tho -- symptoms look like freeze damage.

    BillMN-z4a thanked bengz6westmd
  • 2 months ago

    Yup, i've been noticing other evidence of that late freeze we experienced, doing more damage than I originally thought. Several of my other 'Frost Hardy' specimens have shown damage. It must've hit right when the juices were flowing here and with colder temps than registered.


    The thing about an oak tree, its very strong, long lived, and 50 years from now, any evidence of damage will most likely be inside the tree by then.

    It's just if I want to look at it that long, until it recovers.


    I'll wait until August before doing anything drastic.

  • 2 months ago

    Opinions from some of you tree scientists appreciated. 😉


    There are many side buds sprouting out of the main trunks of this Quercus bicolor.

    Q: Would it be better to prune off the dead branches and upper trunk?

    My thoughts are, that those dead parts of the tree might still be draining energy from the vascular system, even though they're not completely dead.


    Or would it not matter, to just leave the dead branches on for a while.

    I'm thinking the new growth would receive more sun if out of the shadows of the dead stuff.

    The sprouts on the right, that are level with the lower branches, are the highest sprouts on the tree and I'm considering letting those be the new main leader.


    Entire tree (East side).


    SSW side, just to show another view.


    So, what's the verdict?

  • 2 months ago

    It's still alive, so it's up to you. If that were mine, I wouldn't give up yet. Perhaps it's a more southern-sourced Q bicolor than can take your winters?

    BillMN-z4a thanked bengz6westmd
  • 2 months ago

    I would also leave it be for a while. Are the branches dry enough to snap off by hand? If no, then I think it's trying to survive.

    BillMN-z4a thanked indianagardengirl
  • 2 months ago

    ' Perhaps it's a more southern-sourced Q bicolor than can take your winters? '


    I think we had a weird occurrence weather-wise this spring. I was finding cold damage on things that shouldn't have frozen, and I took that as an indication of either bad timing on the freeze or colder than indicated for my particular location. idk.


    Either way and being the tree endured previous winters of comparable conditions, it's worth giving it one more chance. It has a strong root system so I'm expecting rapid growth this summer.


    ' I would also leave it be for a while. Are the branches dry enough to snap off by hand? If no, then I think it's trying to survive. '


    I just wonder, being it's a smaller tree, if it will take more energy to try and restore the damaged branches, then if I just let the new growth grow and by end of summer, have new growth that is 3-4ft. tall.

    I know that's asking a lot, but I'm not really educated on these types of things and am looking for the most efficient route to take (I know it might not be that much difference)


    Thanks all for the input!


  • 2 months ago

    6-30-2026:


    After further investigation;


    This is the 'Jack Knife' scratch test on the upper trunk and branches.

    Completely brown and drying wood beneath.

    Didn't snap when I bent it but no visible moisture in the bark.


    This is the upper main trunk cross section.

    I'm not sure it this shows a pathogen but drying wood with black markings (my saws aren't surgically clean so could be rust).


    So, I think I wondered too long and with all summer for regrowth ahead, why not start now?

    Here it is, cut off just above the bottom of the lowest branches.

    36" now from the top of the trunk to the ground.

    The top of the trunk, where I cut is 1-3/4" diameter, counting thick layer of bark.


    There are two sprouts at the top, 1/2 inch apart, for now, one is back up. I think it grew 1/2" during the time I was cutting off the trunk. 82d and Sunny and to us, hot.

    Should be full, direct sun, all day on it now. It was on the shady, north side of the trunk.


    4ft cage of chicken wire to prevent catastrophes. 😉

    Lots of leaves expanding on the lower trunk for photosynthesis. We'll let them be until there's more growth on the top end.

    It's like 'DejaVu' like I've done this sometime before in the past. 🤔

    Maybe time to give it its final fertilizer application for the summer.

  • last month

    Looks promising. 😌


  • last month

    100% not oak wilt, Bill. What you are looking at is Mother Nature reminding you that you have planted an oak tree north of its native range. And winter really flexed its muscles this year, at least at some key moments. https://www.srs.fs.usda.gov/pubs/misc/ag_654/volume_2/quercus/bicolor.htm


    I have numerous dead swamp white oaks and many more with stunted leaves and little to no growth. Which normally suggests root damage in my experience. Further evidence, I dug up a handful of the dead trees and found that the thin root bark easily flakes away and falls off of the rest of the root. These trees most certainly were alive last fall and growing vigorously the previous summer.


    I just can't pinpoint the exact event or time frame that pushed these trees to their hardiness limit. What we did have in my area was very limited snow cover all winter with strong winter winds blowing bald spots throughout my fields. We likely hit 25 below on back-to-back nights in January with this limited snow cover. And we also went below zero in mid-March and had that 65 mph gusty, all-night windstorm in freezing temps in March. Were some trees already waking up at that point? Maybe.


    I'm not an outlier either. I just found out that two larger, reputable nurseries here in MN also have a very big number of dead and stunted swamp white oaks. And both of those places are further south of where I'm at.

    BillMN-z4a thanked mntreegrower
  • last month
    last modified: last month

    Thanks mntreegrower!

    I was leaning towards cold being the factor also.

    Quercus bicolor is rated zone 4 here: https://www.mda.state.mn.us/cold-hardiness-list

    And no doubt I'm on the fringe of zone 4a. but last winter was mild with plenty of snow cover, all season. And our coldest month was January with -27 for a few days in a row early but generally a zone 4 winter.

    It could be it came back a little on the weak side last season, with minimal growth but plenty of acorns (a sign of trying to survive?).

    We did have lows for 3 or 4 days in the low 20's the last week of April with 21 the lowest, and that was a week after several days in the 70's and 80's, then a repeat a few days later.

    I'm thinking that's the events that did it in.

    Also, the bicolor oaks at the Freedom tower, where I acquired the acorn, is said to have had 3 or 4 different seed collection sites, one was Virginia, so maybe mine was a southern collected source IDK.

    Being it is special to DW; I'm inclined to try one more time with the understanding that if it freezes again next year, I get to remove it and replace with the tree of my choice. 😉

    Thanks Again!

    P.S. The warm weather and then the freezes, would explain the half open, frozen buds on several species of Spruce trees I have here. 😒

    P.S.2

    And the reason the T. plicata and C. nootkatensis bit the dust also. Too hot, too early, then too cold.

    Another reason other than not cold hardy for things to die.🤔

  • last month
    last modified: last month

    Just an update:

    The new main leader grew so much I thought it could break off, in a TS wind.

    I've had that happen before to new growth, and this one is really close to the top edge of the cut. I just go by my premonitions.

    The fix for now is a garden stake tied to the main trunk. It's pretty solid.

    I'll see how the new leader reacts and adjust accordingly.


    I removed any branch that was lower than ~20" on the trunk.

    There are so many branches, and they all continue to send out subbranches as they grow taller, so I think what's left will soon be quite a canopy, with giant leaves.

  • last month
    last modified: last month

    Keeping w/the Q bicolor theme, here's mine described as a "Schuettes" oak by OIKOStreecrops and now about 19 yrs old. "Schuettes" is SW oak x burr oak, however, I see no influence of burr oak on it. For many yrs it always came out w/deformed leaves, tho didn't seem to hurt it much. Then, 4-5 yrs ago, that problem went away and it is growing quite well. Leaves are very shiny as seen and bark has the characteristic flaking of SW oaks. Tree also has a very distinctive, "rough/ancient" look in the winter.



    PS Weeds in front is the septic field which I leave unmowed.

    BillMN-z4a thanked bengz6westmd
  • last month

    Nice oak beng.


    My Q. macrocarpa (bur oak) has always been slow, but it is growing in some of the poorest, sandiest soil (in the world) in that area. The lilac hedge also sucks moisture, nutrients and everything else out of the ground for 8 ft. both sides of the hedge too.


    And every year since planted it, the leaves would come out fine but then show symptoms of what looked a little like 'Oak Leaf Tatters'.

    I never could figure it out and the tree would finish out fine, so I wasn't too concerned about it.


    Now this year, I don't know if it was the 8 lbs. of 10-10-10 fertilizer I spread liberally around the base and root zone, beginning of April, and then flood irrigated around the base, at least once a week, then a month later (May), I spread another good layer of 30-0-4 around it again and kept up my flood irrigation technique (got some good rains too), well yeah, now that I think about it, that probably was what helped it. 🤣


    Anyways, it appeared have a little of the leaf tatter early on and I was a little puzzled why it only put out around a foot or so of new growth, which was better than it ever did, but then to look at it now, it's the healthiest I've ever seen and it's in the process of growing a second flush as we speak, to what looks like another foot or more.

    View of the crown: Much denser than in earlier seasons.


    Whole tree: There's two leaders going up but it's an oak so no big deal.


    >>>>>>>>>>>>>>

    Quercus bicolor: The two topmost leaders, switched dominant roles. The right most was first to sprout and the larger of the two but in the last couple of weeks, the left most leader took over and is 24" long while the one on the right is only 13" and thinner.


    You can see from the opposite side, the new main leader is precariously positioned on the leftover of the bottom of a branch that was there after I sawed partially though it, when I cut the tree off. Hence the concern of possible breakage.


    If you look closely, you can see the living bark beginning to encapsulate the open wound (both in the above picture and the one below.


  • last month

    ' foofy red maples', drought intolerant, sun scald prone, the list goes on. 😉


    I have one red maple left, in the front yard, and even with sun scald tubes in place all winter, into spring, that tree still managed to acquire a sizable 'Sun Scald' on the SW side of the trunk. I'm attributing that to the 80d temps we had mid April, then a spell of much below freezing several days later.


    Acer Rubrum: woods dug circa 2016.

    Encapsulating nicely (yes, It was fertilized and watered early spring, followed by deep soaking rains and subsequent waterings).


    Still on the spindly side growing on poor sandy soil.

    Probably nearing 20ft. tall.


  • last month

    07-27-26:

    Update! ;-)

    Tying the main lead of the Bicolor oak, to the vertical stake didn't work out as good as expected. Even with flexible, loose ties, the wind would whip the trunk back and forth, rubbing it onto the stake causing damage to the tender bark.


    Upon inspection, I was pleased to see improvement in the connection where the new trunk and the original trunk intersect.


    The base of the new trunk has almost swallowed up the piece of branch that was leftover from where I cut the main trunk off. There might be a scientific reason for this but I have no idea about that. ;-) I just know what I've seen happen with other trees, especially younger ones.


    You can see from looking at the opposite side that the other competing leader decided to take a more horizontal direction, I suppose to be a side branch. And that's fine. I'm hoping the combination of the two, will make for a strong bond at that point, supporting both, as one will be the main trunk as time passes. Both have lignifide and are getting woodier.


    Here's what the new 'Tie' looks like.

    It's a soft plastic, flexible tube and it's not connected to the tree at all. The new trunk can move around in any direction, that the wind pushes it, but only so far, keeping it from breaking off hopefully.


    So, now almost 6ft. tall with 10" long leaves (in places).

    I've kept the extra branching somewhat in check but will evaluate things next Fall and spring to see what gets removed and what stays. Same as structure pruning.

    (the branch on the left is the other coleader).


  • last month

    That thing wants to LIVE! Hope this coming winter is mild so it can continue to recover

    BillMN-z4a thanked John
  • last month

    Thanks John.

    But I'm hoping for a normal winter so I can find out one way or the other if this tree will live in my area. If not, I'd just as soon get rid of it and plant something that thrives in this location and I don't have to pay special attention to it. Time will tell.

  • 11 days ago
    last modified: 11 days ago

    Update:

    8-23-2026

    Yesterday, the Bicolor Oak reached 8ft. tall.

    5ft. of new growth just on the main leader (not counting side branches).

    The tree is just beginning to show signs of hardening off but probably will stretch up some yet.


    The new upper main trunk is close to 3/4" diameter just above the point where it sprouted from and encapsulation is progressing. And we should see more of this happening, yet this season.


    I restrung the support ties bc they appeared to be cutting into the trunk a little but really weren't that bad at all. So, while I was at it, I thought I'd take a few pictures and do an update. 😉

    The new trunk is plenty strong and might not have needed any supports, after all it is Oak wood. The new trunk may have an offset from the main trunk for a few years but is growing pretty much straight up with a mild 'S' curve to it.


    ;-)

  • 11 days ago

    In your last pic, the one smaller top-sprout may be best to cut off, perhaps this fall or next mid-spring. There's alot of (relative) weight there on that lopsided area trying to snap that whole top-sprout area off.

    BillMN-z4a thanked bengz6westmd
  • 11 days ago
    last modified: 10 days ago

    That's a good point beng.

    And fwiw: I've been watching this all very intensely since its conception. 😉

    What I plan on, is removing all those extra branches on the trunk, except the new main leader of course, but thought I'd wait until the tree goes dormant.

    And the reason for doing that is, from what I think I know 🤔, is that all/most? of the nutrients/sap go down into the roots for the winter and cutting the branches off then (within the preferred pruning time for Oak) would be best all around (leaves will be off by then too).

    The lopsided area actually is one solid piece of wood (with a little 'step' in the cut) and the branch in question (far left) is connected to a different part of the trunk and is only about two feet long.
    I'm hoping it will last until I cut it off.


    I removed several, half developed side branches during the growing season, bc they were so numerous and wondered if doing that could have adverse effects.

    So, a lot could happen before Fall, but so far things appear to be 'on schedule'. :-)

  • 10 days ago
    last modified: 10 days ago

    I hope your SW oak makes it. Could be the root system was not far down enough to prevent the whole system from freezing solid, which caused serious root & stem damage. And/or the bad late freezes caught things in the emergent stage that is not as freeze-hardy as fully dormant. Certainly many of my trees looked badly damaged from the freezes, but did fully come out from secondary (backup) buds. I noticed the backup buds on ginkgo actually lie in the same "spurs" where the killed primaries were -- but the leaves from them are only about half-sized as normal. OTOH, some trees like redbud put out bigger leaves than normal. From my observations, the secondary buds of trees/shrubs did not have flowers/catkins in them.

    BillMN-z4a thanked bengz6westmd
  • 10 days ago
    last modified: 10 days ago

    Thanks beng,

    It's not that big of a tree so if it does survive, in a couple of years, you won't know there was anything wrong with it. I wouldn't try this with an older, larger tree.

    I don't think this one would've came back from 'secondary buds', it was like the tree was 'woke up' with high temperatures for several days, then frozen solid again, twice, killing the phloem layer.

    Again, it's a young tree and tbh, I'm not sure if it was planted in that good of a spot.

    NBD, we'll see what happens next spring.

  • 8 days ago
    last modified: 8 days ago

    Probably for a lack of better things to do, but we will get 'Gale force winds' yet this Fall.

    So as a preemptive measure, with 4 ft. of new top sticking above the previous support, I made a new, higher and stronger support for this tree.

    You can't buy these in a Hardware store.


    It's a heavy wire shaped and covered with flexible plastic tubing, completely enclosed, forming a circle, with no place for the stem to get 'caught'.

    The stake is the 4 ft. plastic coated steel garden stake, a little heavier (3/8"?) than the shorter stakes that I have.


    The old support was only 1ft. above the top of the old trunk. This one is 2 ft. above and what's above the support, 3+ ft. is thinner and more flexible.

    I was surprised how stout and well connected the new trunk really is.

    To the point I wondered if it needed any support at all, but I know how strong of winds we can get here, both spring and fall and you can't do anything after the fact, if something fails (note the upper part of the new trunk is directly above the old trunk, and it did this all by itself).


    The longer stake allows for more support on the lower trunk too.

    It's tied to the main trunk in 3 places now. Rock solid.


    Not that a severe storm can't still do damage, it's just that you do what you can to protect things, that might be damaged, by the things that are likely to happen. ;-)

    If we have an 80mph wind, it could be all bets are off. idk.

    But once the leaves have fallen, it's a non-issue.


    :-)