Tree lilac dropping leaves

[ATH]

I was taking care of some other trees on this property last summer. The Japanese tree lilac was thin - the owner said it dropped many of its leaves in the spring.

It is doing it again this year. I know: it is a little deep, and the fabric under the stones isn't helping anything out...but this looks more biotic.

Notice also that some of the flower structures started to bud out, but have since wilted. Others look good. I scraped open a few twigs and didn't see any dark streaking in them. I only noticed the one group of dark leaves...everything else is green. When she called and told me about it this year, I wondered if there was a lilac petiole borer that I was unfamiliar with. I didn't see any evidence on the tree that would suggest this though...just the timing and the leaves falling off green but wilted.



I'm honestly not sure what this is. Thoughts? Thanks!

 

[JD3000]

Try Pseudomonas. Also take a look for other contributing buggers like clearwing borer past damage

Not the leaf spot that I have been seeing more and more on these dudes, Psuedocercospora.

Elephant...if it's in the olive family...

 

[ATH]

Hmmm...plausible. The pictures I am finding online seem to have more leaf blackening. Sinclair and Lyon briefly compares it to frost damage as the infection makes the leaves more susceptible to freezing.

No sign on the trunk of borer damage.

 

[southsoundtree]

Some biotic/ some abiotic stressors?
Primary and secondary issues?


How are girdling roots looking?

 

[ATH]

I didn't see evidence of girdling roots, but we didn't pull back landscape fabric to look too hard. There is a top of a root flare and not an obvious flat side, so if there is one there, it is not going to be too bad.

Before I do a more significant RCX, I'd like to know what the disease issue is and whether that is something that is going to cause bigger problems than we can fix.

 

[DSMc]

Could be many small things over time that are now starting to have an effect. What chemicals have been used in the lawn care? Watering schedule appropriate for species and soil type? Things like that can favor detrimental organisms and reduce potential systemic tree defenses.

 

[southsoundtree]

I didn't see evidence of girdling roots, but we didn't pull back landscape fabric to look too hard. There is a top of a root flare and not an obvious flat side, so if there is one there, it is not going to be too bad.

Before I do a more significant RCX, I'd like to know what the disease issue is and whether that is something that is going to cause bigger problems than we can fix.

FWIW, a garden hose running water on fingers wiggling the soil will get you a quick peek, easily, often with tools already there.

 

[JD3000]

Not that ya don't know this...lose the rock and fabric...mulch and flagstones for a walking surface. Ajuga or Thymus between stones will spread and looks pretty cool if they're interested in different design elements

 

[JD3000]

And not for nothing but ATH probably knows all our recommendations, I would guess he's hoping someone sees some specific bugs and crud but a complex of negative elements seems likely here. S. reticulata is a pretty tough dude bit watch for leaf spot to set it now that the trees is stressed

 

[ATH]

Yeah...i told them last year that the fabric is no good. Will emphasize it again. I agree there is probably a complex of problems. No shortage of moisture last 2 springs...but fabric could be reducing to this tree just enough.

I'm pretty sure some pathogenic is going on with the wilting. If it is just another stressor then I'll push hard to change everything else. But if it is something more severe I'd like to give them realistic expectations and probably not invest in other work now.

 

[JD3000]

Samples to Nancy Taylor maybe? That leaf folding is odd, maintenance records available?

 

[ATH]

The C Wayne is probably my next step...by Nancy retired didn't she?

No records. They just bought the place several months before I was first out last year.

 

[JD3000]

Did she? I'll be damned. She's helped me a lot over the years, some good give and take conversations too.

She'll be missed.

 

[ATH]

I heard that somewhere earlier this year. Just looked at the website: https://ppdc.osu.edu/about-us/personnel and it lists lab director as vacant.

 

[guymayor]

I didn't see evidence of girdling roots, but we didn't pull back landscape fabric to look too hard. There is a top of a root flare and not an obvious flat side, so if there is one there, it is not going to be too bad.

Before I do a more significant RCX, I'd like to know what the disease issue is and whether that is something that is going to cause bigger problems than we can fix.

Cart before horse. Spend 2 minutes with a trowel to assess RCX, FIRST!

 

[ATH]

Wasn't as deep as I expected. 2" down I found the tops of the main roots.

A lot more leaves down today. Just a few are off color. They are still very moist/pliable as they are coming off...not dry and crispy.

Samples sent to the OSU clinic.

 

[JD3000]

Check that U of California book for specific herbicide symptoms. Sometimes pre-emergents can affect certain species differently.

Weird man.

 

[ATH]

Good idea. I kinda forget about that book. The only thing in Abiotic Disorders for S. reticulata is a note that it is tolerant of alkaline soils. Looked through the herbicide portions and those talk about color changes.

No pre-emergents (yet) in the planting beds this year. They did put Preen down last year - but after the leaf drop started if I understood correctly. Don't know about years before that.

I think we are on the way to changing to organic mulch. She doesn't like the stones. Also said they have more weeds here than they did at their old house with traditional mulch/no weed mat. Needs to consult with husband.

Maybe this is a better question for a new topic, but since we are here: If she wants me to do that, would you take out all the stones or just move them out of the way, remove the fabric, then rake the stones back out and incorporate them in with an airknife, finally top dressing with wood chips? They are mostly quartz, so should be non-reactive (at least compared to limestone!). I'm just imagining what a pain it will be to haul away a few tons of stone...and to where? Somebody would probably want them, but they'd probably want them washed first. They'd probably make digging and planting a bigger pain through the future.

 

[JD3000]

Sell a rock garden design and install elsewhere in the yard?

Wouldn't want to move them either.

 

[guymayor]

re stones, I would not incorporate any on purpose.

And sorry to be picky, but you did an FX. It's not an RCX until you get down to where the buttress roots divide. It still might have SGR's down there...