Difficult to say.

Please post pictures.

Yes, pictures and a brief history of what may have gone on in the area. Also, I see you are in zone 9. Maybe I'm wrong but for the most part, birch are decidedly adapted to cool, moist climates, and zone 9 mostly isn't that.

Also-and sorry for hijacking your thread to add this little teaching moment-we never "feed" trees or any plants for that matter. That's what photosynthesis does. We only ever provide a few mineral nutrients which the plant can use to "feed" itself. And a stressed plant rarely will respond well to fertilization. In fact, it usually goes the other way, the addition of nitrogen at a time of stress tending to force the stressed plant to put on yet more top growth-at the further expense of the root system. That's not helpful.

There, I'm done.

Birch are also intolerant of drought...the only zone 9B in North America that I know that is cool enough to grow birch is in California which is decidedly dry. If you haven't been watering (restrictions & all), then they might have died from lack of water.

Feeding them probably isn't necessary. Watering probably is. I routinely plant saplings at my Mom's place were I can't water them often, and I assume most will die. (I buy cheap bare root and assume a 33% survival rate) Birch are cool climate trees that struggle in zone 9 under the best conditions....doubt they could survive zone 9 without being watered the first couple years

OP hasn't yet responded but I'd like to take this opportunity to talk about where birch really grows well.....and that is along the shores of the Great Lakes. Lots of trees can reach 100 ft. but in most yard situation, paper birch-yes, Betula papyrifera, rarely surpasses maybe 40 ft. Yet along the Lake Michigan shoreline in several counties near to where I write this are paper birch easily overtopping 100 ft. in height.....and they are healthy and still growing. If you've never been, the temperature swing observable on the Lake Michigan shoreline on an otherwise hot day can be incredible, as in unbelievable. we've driven over to Point Beach State Forest on really hot days-temps up in the 90s, dewpoints in the 70s-only to have to put our hoodies on when we got to that place. Amazing nature's air conditioners. And the same is true down in my "cedar swamp" up at the tree farm place. There, birch growing in close proximity to native Thuja-truly magical places full of old-growth characteristics-are able to live lives double, triple, even quadruple the puny lifespans of that same tree stuck in some hot bluegrass yard somewhere.

There ARE birches native to California (Betula occidentalis) so not out of the realm of possibility that birches are all that uncommon in CA. And they are not restricted to just native species......a variety of birches are commonly planted in NoCal......far fewer in hotter, drier SoCal. But they all will need regular irrigation........no birch tree that I am aware of is very drought tolerant. And drought stress can lead to other issues with birches as well. Reports of issues with birches growing in CA have been rather common lately and most are due to the extended CA drought and insufficient water.

Ah,. Sorry. I was assuming they were newly planted, and you were in Southern California. A mature birch tree shouldn't need any care except during a drought or heat wave. They seem reasonably well sited, and don't look beyond hope. Any sign of birch borer? Any new construction near them? Is the edging new?

Peach and cherry are very prone to disease, unfortunately. Keeping fruit tree happy and productive is its own thing...you might want to post pictures of those on the Fruits and Orchards forum.

But there were not any green leaves. All dead branch and leaves on the trees.

I didn't water them last summer. Last summer was very hot and dry. Are they still alive? thanks

The second picture looked like there were leaves on it. If there weren't...scrape the bark. If there is green underneath it, then it is alive. If you break off any of the twigs, are they green?

Hot & dry summer with no irrigation could certainly kill a birch. Unfortunately, they don't recover well either.

The bark at the base of one of them makes me think these are Betula pendula, the European version of white-barked birch, to speak simply. This species is a magnet for the serious insect pest bronze birch borer. I have no idea if that thing exists in any part of California, but if it does, it *could* account for this poor result. But usually, that's a more drawn-out affair, with the top portion of the tree dying first. Evidently, these just didn't leaf out this year, so that would point elsewhere.

One thing to keep in mind-far and away the most common causes of plant performance issues are environmental, not insect, not disease. But to rule out (or in) BBB, look for small D-shaped holes in the trunk.

The bark at the base of one of them makes me think these are Betula
pendula, the European version of white-barked birch, to speak simply.

Yes I can confirm that, it does look very much like it. They are pretty drought tolerant actually, but not california drought tolerant

A drought of the magnitude which hit Cali last year will absolutely do for betula pendula - we have seen struggling birches here in semi-arid east anglia.

Heh, the European birch got planted en masse back in the 60's and 70's here in the upper midwest. No idea why-it's a dog on this continent-but I knew that was what I was looking at. For that matter, a similar mistake is unfolding today as no matter where one goes in this state, the "experts" are placing river birch-and only river birch-on lists of native plants good for our area. Not even close. That tree is good where soils are acidic, which most def. is not the case here in limestone land. Dumb....real dumb.

One pic also shows a tree "installed" similar to how a telephone pole would be installed. Way too deep, no sign of root flare, take these miserable things out of their misery.

I planted some vegetables around the trees last year . I am afraid that it may change the environment of the birch tree. Thank you! I hope one of them can survive.

I see Birch trees dead and dying all over southern California. I first noticed this last year . Lots of my neighbors birch trees dying ..

This year I see even more.
Sad..

It is happening around here as well.

Maack, what your link is describing is normal forest succession, albeit, after the wave of destructive logging, which did alter things. So, these NE Minnesota birch-I've been up on the North Shore and it's quite a region-are simply reaching the end of their natural lifespans as early-succession species. What is missing or disturbed is the opportunity for pine, spruce, fir and cedar to regenerate, the way they have for millennia, under birch and aspen pioneer forest stands. The "mother trees" are lacking, due to the explosion of deer following the big logging wave.

In and of itself, this is not like what is being described in Cali.