quercus agrifolia crud?

peteyt · Sep 18, 2010

HI,

I have seen this in a couple of coast live oaks i do things for in Oakland, CA. This one tree in particular has quite a bit of this sort of thing. Lesions (?) on smaller branches, only some of which have this webby growth on it. Most don't. The branches seems fine and keep on growing out and out, but I have seen it around and wonder what it is. I haven't seen anything like this in the oak diseases handbook i have. I hope to bring my hand lens to bear on it the next time i see it.

This tree is a vigorous grower and otherwise appears quite happy. It has probably gotten too much summer water and we are cutting back on that. It has a fair amount of beneficial wasp galls on smaller twigs, but i mostly leave them on for, you know, the Nature and its Mysterious Ways. It was lollipopped long before i starting working on it and I work to get it back into shape (as much as possible for the twisted tree it is!) as it attempts to swallow the house and shade out a very lovely garden of native plants.

the photo was taken in mid-June.

Any thoughts? seen this before?
thanks,
pete

cerviarborist · Sep 19, 2010

Try attaching the photo again, peteyt.

peteyt · Sep 20, 2010

aha, let's try that again...

peteyt · Sep 20, 2010

ok, again again. the controls are bucking, apparrently.

trees4ever · Sep 20, 2010

Looks like an initial oak twig borer caused some damage and then woolly oak aphids came on board.

But if you peel the bark back and see spiraling tunnels along the branch/twig then it's probably the oak twig girdler.

All these guys are often around the Q. agrifolia.

-Diane

peteyt · Sep 20, 2010

Fascinating ... I'll get read up on these things in the big, expensive books.

They don't appear to me to be a long-term problem from how they are affecting the trees. And they are critters that live around here, so I don't want to harass the ecology too much...

But then what do I know? Am I being a little happy-go-lucky about these? I'll be doing some reading about it, but I am very into everyone's thoughts as well. I do want to do the right thing, as I do care for a few q. agrifolia in this block.

The wool from the aphids I don't see very much, the oak twig borer damage (?) I do. I look forward to getting back over there and digging around inside the branch with a lens.

thx, Diane!

nuthin_special · Sep 21, 2010

Not that i know much about Q. arifolia but that doesn't look like borer damage. No sap flow, no wood shavings and the callus tissue at the margins suggest a fungal canker.

trees4ever · Sep 21, 2010

NS - fungal and canker pathogens can be secondary to the initial causal agent.

There are some signs of elongated bumps spiraling along the bark so that makes me think boring activity may have come first.

Pete has got to do some further investigating but then that's the fun part!

And remember Nature has amazing checks and balances.

-Diane

peteyt · Sep 24, 2010

thanks for the suggestions, all. I am now far more intrigued than i was previously.

I will be certain to do a more exhaustive investigation when i get back over there - silly me for not bringing a sample back to slice open. Ahhhh, pruning productivity kicked science out the door on that one - lesson learned.

I felt as if there was, as said, an initial agent and then some secondary influence.

i dug up a couple more images from another stem, this time with no "wool". This is younger wood, smaller stem. perhaps we are seeing a little closer in time to the initiation of the process.

another image attached (gotta figure out how to inline these images to the thread next time!)