Saturday, December 7, 2013

coast live oak ~ 12/07/13 ~ Fort Ord


As we were driving out to the Creekside entrance on Hwy 68, I noticed most of the oaks had dead tips.  Speeding past, it looked like a deep green mosaic with scattered bits of tan.  I don't think this is sudden oak death, which is caused by a fungus-like pathogen.  I'm guessing it's caused by true fungal diseases, some of which apparently show themselves more when the oaks are drought-stressed, like this year.  I'm not quite sure how that works since fungi generally like moisture.  Right?  This looks very different from the swaths of entirely dead trees I saw last year at Toro Park, which is located right across the street of Hwy 68.  The U.S. Forest Service Pacific Southwest Research Station has an excellent technical report "A Field Guide to Insects and Diseases of California Oaks".  Maybe it's Diplodia quercina branch canker (pp. 88-89) or Cryptocline cinerescens twig blight (pp. 76-79)?  I really don't know.  I'm no tree doctor.  Half the time I can't even distinguish coast live oak from other Quercus spp.  In any case, this widespread dieback is interesting to note.

ps 03/12/14 - An intern from a local paper The Californian contacted me regarding this post.  She wants to use my pictures and information in an article she's writing.  This is the first time I've ever been contacted by a newspaper for Nature ID, so it was an interesting experience... I think for the both of us.  She was sweet but sounded a little nervous.  I gave my photos free of charge, because I didn't want the hassle of creating an invoice and dinging for payment (so many places conveniently "forget" to actually pay).  I'll link to the article once it comes out.  Cool beans.


Jeannette said...

The utmost tips being so uniformly brown against the green leaves does suggest the drought may have something to do with it.

GretchenJoanna said...

This is really's amazing the defense mechanisms in nature. I have just this fall been trying to learn which oak is the (broad category of) Live Oak, so your post is timely, one more repetition of the information. I came up with a mnemonic to help me remember: the little barbs on the leaves, when they fall on a patio or deck, help the leaves hold on for dear *life* when you are trying to sweep them off.

Katie (Nature ID) said...

Hey, Jeannette. It's interesting that the leaves, other than being dead, have no other markings, no blisters, no irregular edges. I wonder if all dried, dead on the twig leaves are due to fungus, or if it can happen *only* due to drought?

Gretchen, I don't know, black oaks are deciduous and they have pointy barbs. Check out Las Pilitas Nursery's excellent series on CA oaks:
California Oaks I

California Oaks II

California Oaks III

California Oaks IV

GretchenJoanna said...

uh-oh ;-)
Thank you for the links - I will start studying again!