No, glyphosate would cause yellowing, then drooping.

This looks more like root rot.

@UpperBayGardener (zone 7) Well, that's bad. The soil is very well drained, so I am wondering how that is even possible. How can I confirm your suspicions?

I agree with david. Wilted or drooping leaves even after a good watering most typically indicate a root rot. Planting too deep could be indicative of a root issue - rhodies and azaleas hate being planted deeply - but I'd be more inclined towards excessive watering. When you say you "spent a week making sure it was thoroughly hydrated ", what exactly do you mean by that?

Overwatering would be my guess, too. Did down a bit at the base and see how wet things are.

@gardengal48 (PNW Z8/9) So the common pattern with this plant over the last two years has been that it wilts when it is dry and responds within 24 hours to a good soak.

The plant sits between two Italian cypress trees. I have well-drained bark soil in the top 10 inches, sitting above the subsoil, which is a clay loam and hard. The roots are fully expanded into that top layer. It would be tough for that well-drained bark layer to hold too much water.

Maybe the roots got down into the clay loam layer, which could get saturated, especially under 10 inches of bark soil.

It is also possible that some potting soil was mixed into that bark soil and changed the water-holding characteristics.

Since historically the soil tends to dry out rapidly, I wanted to make sure that lack of water was not the cause of the wilting. So I watered the plant at least once every two days manually, hoping to see some turnaround, as normally happens. There was no turnaround this time. That's what I meant by "spent a week making sure it was thoroughly hydrated".

So, how should I diagnose this further? I guess let it dry out for three days, and then investigate the roots? But what am I looking for? What's healthy, and what is evidence of root rot?

Maybe I should turn off the drip irrigation system so that the soil really does dry out rapidly?

Hoo boy!! Despite what you may have read, a freely draining soil mix piled on top of a not very freely draining soil will not help much with improved drainage overall, specially if the top soil level is enclosed with concrete blocks. If watered often on top of the drip irrigation running, I am not at all surprised things became water logged.

You can confirm a root rot by digging up the plant and examining the roots. Root rots will produce brown, off-color and mushy roots. FWIW, plants seldom recover well from any kind of root rot.

@gardengal48 (PNW Z8/9) For two straight years, the problem with the soil this plant lives in is that it has been too dry, even when a lot of water is applied. The soil under the 10 inches of bark is not pooling water on top. It does drain at least 2 inches per hour.

I will turn off all drip irrigation and see how quickly it dries out and then investigate the roots.

Should I be focused on the root ends, or examining any part of the roots is enough? How many places do I need to check roots to give the plant a clean bill of health from root rot?

"it wilts when it is dry"

No shrub, and certainly not an Ericaceous one, should be allowed to wilt as part of its normal regime in the garden!

While you're examining the roots keep an eye out for fat white comma shaped grubs. Vine weevils can cause that kind of wilting.

@UpperBayGardener (zone 7) It was never my intention to allow the plant to wilt. I have it on a drip irrigation system that works, and it was drying out in spite of that.

For comparison this is an Azalea with Vine Weevil grubs in the roots.

@floral_uk z.8/9 SW UK The presentation for that plant looks like falling leaves and yellowing? My plant has not started to shed leaves. It looks like the same presentation it had previously when it did not have enough water, only this time it does not respond to water.

In any case, I will wait for the soil to dry out a bit and then investigate the roots. I may transplant it to a container with new soil for a while and see if there is any recovery there.

That azalea has been declining for a while. The leaves didn't yellow and fall immediately. The first symptom was drooping. I'm not saying your problem is Vine Weevils but when you look at the roots bear the possibility in mind.

Vine Weevils and root rot would present similar symptoms since they both cause the plant to be unable to take up water.

I observed very similar behavior in the Azalea I planted last spring. This month, it's showing the same signs again. It's planted on a slight slope and a few inches above soil level. I added plenty of compost last year. This Azalea is supposed to grow up to 5 feet, but it’s currently only about 1 foot tall. Overall it does not seem to be in any danger. Props back after watering.

@floral_uk z.8/9 SW UK So what I am looking for is grubs like the attached photo eating along the root line?

Yes. But they're good at hiding. I repeat, I'm not saying that's the problem. Just that it's a possibility.

In other "things to worry about" news, many years ago I corresponded with a gardener in the Bay Area, now sadly deceased. He said something at some point about how, by his reckoning, he couldn't grow acid loving plants because all he had to water with was municipal water, and it was so alkaline it would eventually make the soil inhospitable for them. I have a well so it's not a concern for me, and besides, for rhodies I kept in pots to size up, most years they probably get 95% of their watering from rainfall. When they are in the garage in winter they just need occasional sips anyhow.

But I'd have to defer to people in your area about how that plays out in practice...yes, I'm aware things like peat compost have tremendous buffering capacity, but the guy I mentioned was a super skilled horticulturalist. I think he knew what he was talking about. It's too bad Sara Malone isn't active here anymore, she might have some thoughts on this. (And for that matter, I feel like there are a couple other Northern California folks we don't hear from anymore.) There was a woman named Cary who had some interesting posts about 12 years ago about growing rhodies in the Bay Area, and I vaguely recall she said she had well water so didn't have to worry about it...but I could be making that up! Or, for that matter, it's too bad Polo retired and sold Sonoma Horticultural Nursery. I also remember chit-chatting with him about his customer base and his saying ~ that he really only sold rhodies to people who had acid soil because there wasn't a practical way to deal with soil that wasn't. [Logically, acid soils in Northern California often correspond to the places with higher rainfall - therefore needing less supplemental water! Why practically all of the PNW has acid soil and no trouble growing rhodies etc.]

Too much alkalinity and sodium (sodium hydroxide or carbonate often added to tap water) could stress Ericaceous plants and make them more prone to root rot, or it could have a direct toxic effect, although I think if fully the latter, it would present a bit differently. (i.e., yellowing)

Good point about the water. I have blueberries in containers because of my alkaline soil. I water with rainwater. But alkalinity would show up as chlorosis and steady decline rather than wilting.

@UpperBayGardener (zone 7) Water does not buffer pH effectively, and it quickly assumes the pH of the substrate. If you had extremely alkaline water I guess that would affect the plant for a short period, until the substrate changed the pH in the water. And I guess your correspondent must have had municipal water with a pH over 8 to make such a comment.

My tap water is a pH just over 7, and I engineer my soil to be at a pH < 6, so I don't think that this is a problem with pH of the water. Someone may have tried to amend my soil with a potting soil that raised the pH some, but would that make the leaves droop?

Do you know what happened to Sara Malone? I see her design website was down as well.

I would never plant an acid loving plant into my native soil here. I always use raised beds or containers, so that I can control the soil pH and ensure fast drainage.

If I have not already lost this plant, I will try to get it into a pot in a controlled situation, and let's see if it recovers. If the roots are slimy I may have lost it.

I didn't say water buffered anything, I said potting mixes or soils with peat had buffering capacity.

Floral - yes, like I said, I didn't think this was wholly direct damage from alkalinity, but rather a case of the plants not growing as well as they could, and that making them more prone to root rot. In cases where I've grown borderline east coast climate tolerant rhodies, like 'Belva's Joy', you really have to get them fully established. I lost smaller Belvas to root rot if they weren't growing at full steam ahead with a big root system.* I think Weste's plant was never really happy.

BTW have you said anywhere which variety this was? Some could more more tolerant to the way you're trying to grow them than others; although there's not the same wide range of adoptability there is in the lepidote or elepidote rhododendrons, it still might be helpful to know.

* - rereading this a few hours later, it's important to clarify something. I've talked about large rhodies collapsing practically overnight from root rot. That can happen and it could still happen to my Belvas - in theory. But the difference is until about 2012, I wasn't super savvy with where or how I planted rhodies. So by the time I planted my second Belva it was on a slope where I knew our sometimes insane summer rainfalls can drain off. I'm just saying, generally, small not fully established plants are the most likely to die off from root rot. The couple times I had a huge Rhodie get killed, I'd put them in a spot w/not enough drainage, and it just took a few years to catch up with me. The way W. talks about about this plant's history, it just sounds like it was never fully established. (even though, superficially it at least, it seems like it should have reasonable drainage, as GG points out, having a differential texture in a raised bed can make matters worse)

And a silly clarification to my clarification - WHY I GROW BELVAS JOY! haha. It's not a super red at all, too purplish. Although the truss is nicely shaped at least. However, it's an incredibly good looking foliage plant. Almost looks like some exotic tropical houseplant.

@UpperBayGardener (zone 7) These are Encore Azalea "Autumn Fire". I agree the Azaleas in this location were never really happy. I think the soil dried too quickly.

Okay, here are the photos after my extraction of the Azalea.

There are no slimy roots or black roots.

There is an extensive root network, and those roots are either stained brown like the bark soil or white.

I don't see any grubs in the soil.

The one thing I do note is that the soil is very dry throughout.

I transplanted this to a very organic soil in a pot, pH around 6. Let's see if it starts to recover in a month. All of the leaves now look like they will die, so it is going to be close.

OK interesting. As I'm always saying about patented and trademarked plants, they were selected for a certain marketable feature, not for being strong garden performers. If you must plant another azalea in that spot, check with whomever in the Bay Area would know these days, which old standard varieties are considered tough in those parts. For example down south, you see old Tabor azaleas in abandoned gardens, so clearly they are hard to kill off. (Alas, just a bit too cold where I am. I found a close lookalike though)

Also consider using collected rainwater to water acid loving plants over the summer, if allowed by your jurisdictions.

@UpperBayGardener (zone 7) The Encore Azaleas are the strongest Azalea varieties I have ever encountered. They are genetically very robust and tolerate more sun than other varieties. You can definitely kill them, but it requires effort.

So the good news is that after I transplanted this Azalea to a pot with new potting soil (pH adjusted to under 6), the plant stabilized and showed new growth. So it will survive.

The bad news is I still don't understand why it was showing water stress when receiving regular water in its original location. It looks like the location between two Cypress trees was very rapidly sucking up any water in the top soil layer where the Azalea lived, so the Azalea was never able to really get a good drink of water.

In situations like this, is there anything I can do to amend the soil? I could add a touch of clay loam or compost to try to hold more water, longer?

I'm glad it's doing better for you.

A quick clarification - although I do believe patented plants are generally not selected for garden worthiness, that was never the issue people had with the Encores. The issue many people did have was not being as hardy as advertised. Probably because they'd used tender species in the breeding lines to impart the reblooming trait. Obviously, that wouldn't ever apply to you in 9b...practically any plant commercially identified as an azalea, even belgian greenhouse varieties, would be hardy for you!

The funny thing is, in researching this, I realized I'd had the ID of a plant in my garden wrong for many years (in my brain at least!). I thought I had at least one encore, 'Autumn Embers'. But reviewing notes in my plant database, I see the one I thought was that, was actually Marshy Point Red Magic. I found a note that the Autumn Embers had died in 2011, even before the polar vortex winters.