Can a pesticide trigger a chemical release and cause healthy leaves to drop?

[Stant82]

Hey guys!

I have a client whose Red Oak is dropping its leaves. The yard looks as if a storm or very strong wind came through and just blew some of them off. All the leaves have fallen off at the abscission point and there are no other signs of leaf stress or decay. ( see pics ) There are 5 weeping spots on the trunk but no holes or signs of an exterior wound. None of the other trees on the street have been effected.
Through a long conversation I found out that he moved in 2 months earlier so I don't have any history of the tree before then ( but it obviously had been over pruned at one point ). The only variable that was unique to his yard was the application of a " natural " pesticide.
He called to company that applied it and they said it was:
Intice perimeter bait
Demand CS
Applied to potato plants a the root flare.
I found the chemical data sheet and turns out its pretty much all greek to me

I've included the pics I took for reference and any thoughts would be very much appreciated.

 

[JD3000]

looks like bleeding from a Phytophthora or two lined chestnut borer. Bacterial wet wood is another possibility as is stem girdling in some circumstances. Hard to say from pics as a thorough on-site inspection is necessary.

Hope I've pointed you in a decent direction.

 

[JD3000]

not sure why a pyrethroid would have been applied to the bases of the sweet potato vines as it isn't systemic. Also, it is very much not natural, biorational, or organic. I suppose a massive overdose could cause symptoms in an oak but it would have also likely fried the annuals as well.

 

[jed1124]

Possibly hypoxylon canker? I don't think the spray has anything to do with the tree.

 

[TreeVB]

Hypoxylon canker is secondary though correct? How does the root flare look? From the photos it could be a good candidate for a RCE?

 

[JD3000]

I would want to see if the bleeding area are above sinuses where roots meet up at the trunk as well.

 

[Stant82]

The lowest "bleeding" spot is about 20 inches up from the root flare, and the highest it at 4.5 ft at the top of the trunk .

I did inspect the root flare and recommended the removal of the ring. The flare was partially buried, but i guess when you get so used to seeing trees planted below ground level just a little flare exposure looks great. I know the importance of allowing the flare to have air and be dry but wouldn't that be a secondary issue in relation to the leaf drop? Yes it is an additional stress factor on the tree, and I have performed 100's of flare exposures but never seen any correlation between leaf drop ( at the abscission zone ) and a buried flare.
The client's initial call was in relation to the leaves and the lack of site history has left me with very little info.

[ QUOTE]

From the photos it could be a good candidate for a RCE?
-------

RCE? I'm not following.

Phytophthora trunk canker-- Yep I can see that as a possibility. We're down here in north Texas, Dallas area, and we have had an unusually high amount of rain this summer.

 

[JD3000]

Flare could still be in play if SGRs are impeding xylem and phloem. If flow is inefficient or impeded, the tree can drop leaves, sometimes to conserve resources. Interior leaf drop or exterior?

RCE/RCX is root collar excavation/examination.

I would want a clean look at the bleeding areas and send a swab for lab analysis. Wetwood usually foams up when sprayed with a trunk spray rate of a phosphite fungicide. Ask the lab first if it needs to be delivered that day. Texas is big so that may not be possible I know.

 

[Stant82]

The leaf drop is primarily lower outer canopy from what I can tell, but it was over pruned and the interior canopy hasn't recovered yet.
I'll work on getting more info as soon as I can.
Thanks!

 

[JD3000]

One more thing, don't rule out turf care products. Hard to say given the HO has only been there for two months but the negative effects of herbicide damage can be latent and long lasting.

 

[BuckmasterTreeService]

I would also take a look at the root flare. Move the blocks back and see if they cut into the roots to get the ring to fit. I would guess the ring and foliage were just added to increase curb appeal before it went on the market. They probably overwatered on a regular basis as well. I don't see any signs of hypoxylon. There would be thinning spots of bark with white/tan showing through this time of year.

 

[guymayor]

I would also take a look at the root flare. Move the blocks back and see if they cut into the roots to get the ring to fit. I would guess the ring and foliage were just added to increase curb appeal before it went on the market. They probably overwatered on a regular basis as well. I don't see any signs of hypoxylon. There would be thinning spots of bark with white/tan showing through this time of year.

Yes find the flare so you can see wtf is going on.

 

[oakwilt]

Auxin-mimicking chems do indeed stimulate leaf drop. That's what auxins are. That's how and why 2,4-D was developed...to defoliate.
I'd say from what little I caught reading your post quickly, is that you have a lawsuit if you want it. If any leaf still is holding on this winter..take it for a mass spectrometer indexing.