Struggling with IDing a likely fungus

Matias

Matias

Been here much more than a while
Location
Silicon Valley
I am trying to diagnose what I believe to be a fungal infection on a group of Q.suber (cork oak). The black staining is all the way up and down the trunk/stems, and seems to correlate with the sides that get the least airflow. Trees with buildings immediately west of them have the symptoms on the west side, while those with buildings on their east show symptoms on the east side. All of the ones in the courtyard have solid green foliage, though sparse, but the ones by the road look worse in the foliage and less bad on the trunk. One in particular by the road is yellowing badly, and has black spots on the leaves; maybe sooty mold, but doesn't look right either.

I tried various sites and Google lens to no avail. Anyone ever seen this one and get a god ID on it?

Edit: pictures not uploading. standby
 
The opening on the lower trunk photo looks like an old injury from excavating or landscaping equipment. Overall the site conditions (super compacted soils) would cause all the crown/leaf symptoms especially if the growing season was dry (or too wet). We know for sure that pathogenic fungi are generally opportunistic to multiple stresses on a given tree. This is no help to ID'ing a fungus but that's how I see this situation.
-AJ
 
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From the wiki entry on Quercus suber:

"Cork oak is relatively resistant to pathogens, but some diseases occur in the species. Leaf spot can be caused by the fungus Apiognomonia errabunda. Other fungi can cause leaf scorching, powdery mildew, rust, and cankers.

The most virulent cork oak pathogen may be Diplodia corticola, a sac fungus which causes sap-bleeding sunken canker wounds in the wood, withering of the leaves, and lesions on the acorns. The fungus Biscogniauxia mediterranea is becoming more common in cork oak forests. Its fruiting bodies appear as charcoal-black cankers. Both of these fungi are transmitted by the oak pinhole borer (Platypus cylindrus), a species of weevil.

The common water mould Phytophthora cinnamomi grows in the roots of the tree and has been known to devastate cork oak woodlands.."
 
Q suber is a funny bird. They shed their leaves this time of year, or most of them. This can make them look very sickly, watching the ONE large tree I know of, this also seems to have cycles of heavier shedding years. Of course the cycles can be due to weather..

The sooty dark on the bark seems similar to a sooty mold, possibly due to honey due from aphids? Is this the high side of the trunk? Meaning the area that would get rained on from the bugs?
The wound looks like dieback from a damaged root, possibly colonized with wet wood.
 
@moss I am fairly certain that soil compaction from foot traffic, and of course climate issues are significant contributing factors. The area that looks like an old injury is assuredly not. All that light beige to brown area is soft, as if rotten, and that discoloration is present on the rest of the trees, going way up the trunks, and only in spots. That one was just particularly bad.

@evo I considered sooty mold, and despite the majority of it being on the high sides where honeydew could deposit, the black stuff doesn't come off easily. I am familiar with the leaf drop and how scary they can look at molting time, but only the ones by the street are looking yellow at the moment, and they show no signs of new growth to replace these dying leaves.

I fear it may be the beginning of SODS, but if that is the case, we will know very soon.
 
Matias said:
@moss I am fairly certain that soil compaction from foot traffic, and of course climate issues are significant contributing factors. The area that looks like an old injury is assuredly not. All that light beige to brown area is soft, as if rotten, and that discoloration is present on the rest of the trees, going way up the trunks, and only in spots. That one was just particularly bad.

@evo I considered sooty mold, and despite the majority of it being on the high sides where honeydew could deposit, the black stuff doesn't come off easily. I am familiar with the leaf drop and how scary they can look at molting time, but only the ones by the street are looking yellow at the moment, and they show no signs of new growth to replace these dying leaves.

I fear it may be the beginning of SODS, but if that is the case, we will know very soon.
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Do you think it could be ‘early leaf shed’ due to higher stress being by the road? Sometimes it’s hard to not forget about early shed / late leaf development in the oddballs.
How is the root flair/girdling roots?
 
evo said:
Do you think it could be ‘early leaf shed’ due to higher stress being by the road? Sometimes it’s hard to not forget about early shed / late leaf development in the oddballs.
How is the root flair/girdling roots?
Click to expand...
I mean, I'd like to think that these trees were planted correctly. They don't have dramatic flares, but enough that I don't suspect girdling. Compaction is a near certainty though. I will definitely be monitoring these trees very regularly, as they are at the campus of one of the company's oldest and most valuable contracts, Stanford U. They are also just max size for their sites, so I am recommending a cycle of paclo for good measure. It's been proven effective in a number of similar situations, and their bean counters are trying to tighten down on their tree budget, so I think they're gonna like this approach overall.
 
Update:

After looking around at other trees, and perticularly plants under the affected trees, I do believe we are looking at black sooty mold growing on honedew. There are a number of environmental factors stressing these trees, and since paclo is contraindicated for severely stressed trees, I am going to say that these trees should get an a compost leachate to boost their health first. I will post progress pics when when it's warranted.
 
Also be on the look out for Mediterranean Oak borer.. It hasn’t moved this far north yet but I’m under the impression its moved into the Portland area from down your way
 
evo said:
Also be on the look out for Mediterranean Oak borer.. It hasn’t moved this far north yet but I’m under the impression its moved into the Portland area from down your way
Click to expand...
I saw frass in a few places, but couldn't spot any holes... I will be keeping a close eye on these trees for a good long while I hope, so I will continue to update this post.
 
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Working on getting a penetrometer. I need to figure out how to get some water near the crown to loosen the soil. It's a difficult area to access. I an thinking that a backpack sprayer with water could be enough to clear away the crowns and inspect further.

Sadly, CRZ protection is highly unlikely, due to students not really caring unless they are very strongly discouraged, and nobody is gonna greenlight a fence there. These trees in basically in concrete planter boxes surrounded by lots more concrete, so the soil issues all lead back to that. I would never have suggested this species for this location, so I am basically just trying to polish turds, but I do think that a high quality compost is gonna be as close to panacea as you can practically get. Further, I think that PGRs are gonna be a staple for these trees that have maxed out their entire available space already
 
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