34 is pretty close to freeze... how can you be so sure that your tree wasnt hit???

as microclimates can dictate a higher zone in a given garden... a microclimate can also be a cold zone ..

i know of no other reason for mass leaf fall .. though i wouldnt call 500 leaves a mass ...

on my 5 acres ... i have a mulberry at each end.. 500 feet apart ... upon first freeze... every single leaf will fall off on the next day, near sunrise.. still green ... it did not happen on the same day with each tree this year.. go figure ...

unless the thermometer you are relying on is in your garden.. under that tree ... i think you might be ruling out the reason ... or not.. who really knows.. lol ..

good luck

ken

I used to live and practice in Sacto. Can you describe the area in which the oaks are growing or link a pic(s)? I'm looking specifically for evidence that turf was installed around the dripline.

Thx

Dan

Ken, Our 34 degree night was about a week prior to the large drop. My thermometer is outside, about 100 feet from the tree. The drops we have noticed seem to be in the afternoon. My husband, who is usually not very observant, called me to the window to see a drop the other day. Perhaps there are a lot more than 500 leaves falling, but it looks like its snowing 2" leaves for a few seconds, then quits.
I also have observed my walnut trees dropping all its remaining leaves in a day following a freezing night; I'm greatful for that behavior in my walnut tree that shades my deck so that I can finally sweep the deck for the last time until Spring when the catkins come out.

Dan, my 3 valley oak trees are along my back property line, and there is no turf nearby at all. There are Aptos Blue Sequoias also planted along the property line. My husband does a little vegetable gardening within the driplines (rototilled now for the winter), but the trees are mostly above bare soil.

phytophthora ramorum...Sudden oak death?

Here is a link that might be useful: phytopthora ramorum

Hopefully not Sudden Oak Death.
Valley oaks apparently do not get this disease.

i wouldnt worry too much about leaf drop in mid november ....

and i surely wouldnt start worrying about disease ....

i suspect some weird weather phenom ...

lets see what happens next season

ken

I think it is just a response to the shorter daylight hours. Leaf drop is in full swing here in N TX. The oaks seem to hold their leaves the longest. Maybe your more observant this fall. Best of luck.

You should, of course, be providing enough water for the redwoods, as they require a lot of water - much more than precip. If you drive around the immediate post-WWII neighborhoods in N CA, you will see the majority of redwoods in decline as they don't get enough water.

So.

o Is the water you are providing the redwoods going into the oak driplines,

o is the rototilling more than 33% of the soil under driplines and under the oaks dropping leaves,

o valley oaks are deciduous. They send a chemical to drop the leaves and it may not work all at once in some years.

If you are not watering the oaks nor disturbing their roots (rototilling is disturbing their roots as is gardening underneath them), then not much to worry about.

Dan

Thanks for your comments, Dan.

The redwoods are getting drip irrigated all summer. My husband set up the drip to come on the same time he is watering (by hose) his vegetable garden. He said there are no drip spouts under the oaks. The redwoods look pretty good given our warm summers with no rain. We planted them about 20 years ago when the property behind us (at a higher elevation) got developed with new homes. The trees have given us exactly the privacy we want, and without much mess. Now if only I were able to get them to stop growing any taller, as they are perfect right now! I did not expect to live in this house this long.
So, both the oaks and the redwoods look reasonably happy and pretty healthy. Not much of the soil under the driplines is being tilled.
That is interesting about the oak tree having a chemical that signals the leaf drop------I guess a lot of leaves got the message all at once.
My husband constructed a large raised vegetable bed about 20' from the trees, and no other trees are nearby. Within 3 years he found the bed full of fine roots. Apparently the redwoods were enjoying his watering more than the vegetables could, and he tore the bed down this last spring. But, the nearby redwoods look the happiest of all!

OK. Oaks sound as if they just are responding to environmental cues.

To reiterate, however, redwoods inland in residential neighborhoods eventually die because they can't get enough water. Drip won't be enough soon (how soon is impossible to tell from here) but they'll need an additional ~20 inches of water when they are about 40-50 feet tall. 20 inches across the area of all their roots.

That is the reality. This will require that you irrigate far too much for the oaks' liking. You'll (or the next owner) will face a choice of the redwoods or oaks, and it is very common that both lose in the long run. Sorry.

Dan