Satsuki azalea, health issue?

[gxa]

Hello everyone,

This is my first summer with this Yata no Kagami Satsuki Azalea and I am somewhat concerned about it's health.

What do you think could be the cause of the spots on the underside of the leaves? Fungal issues? Too much water?

I've been root watering it every other day, and fertilized it with organic. I usually water the leaves too, but I stopped doing it since these spots began to spread.

I am in Northern Spain, a coastal area with temperate climate, generally humid and windy. But the plants are on a balcony.

Appreciate your help.

 

[Deep Sea Diver]

Looks like a form of rust … usually from the leaves being wet over night and crowding. Not uncommon. Can happen alot on older leaves during wet fall weather before these leaves fall. Not a major issue at this time.

Wondering if you had a chance to cut the flower site back to two new branchlets and those two remaining branchlets back to two leaves yet?

Standard treatment is spray the underside and tips of all leaves with 2 TBSP H2O2 in one QT of water. This can be repeated every 4-7 days. Spots won’t go away, but the spread should stop.

Please try to ensure the leaves are watered weekly, yet at a time they dry completely off before nightfall.

Cheers
DSD sends

 

[Deep Sea Diver]

Update on my last 2 TBSP 3% H2O2 in one L of water

Best
DSD sends

 

[Glaucus]

Overall health looks pretty good to me. I do see folded-in leaves on the branch in the back. Are those folded up by a catterpillar? I woulkd check.
Usually, should be spread out and opened. Not folded in on themselves.

Yes, those spots are not good. It can be very hard to have an unblemished plant. Looks like it would fit under rust with a fungal cause.
H202 can do very little harm and could limit the spread.
I have many satsuki whose leaves get wet very often, and I do not see rust like this.
I also have less UV light than you so I should be seeing more.
Humid and windy should be good.
So check the spread and if H2O2 doesn't work, try something more potent like a fungicide.
I do not believe they present a risk to the health of the plant, just they look bad and may reduce vigor a tiny bit.

 

[gxa]

Hey guys, thank you so much for all the information!
Seems like there is a consensus on using H2O2 initially I'll do that then.

@Glaucus
I haven't seen catterpillars, don't think that is possible here. But some plants had aphids and lot of ink-like stains on the underside of the leaves, which I guess is from insect poop...so I've been spraying all of them with neem + insecticidal soap the past weeks.

@Deep Sea Diver
Oh, yes. I've read something about that pruning technique. Never applied it though. I will definitely follow that suggestion too!

 

[Glaucus]

I don't think you have caterpillars. They leave obvious damage. I just found it strange that some some shoots the leaves are very close to each other, folded up.

 

[Deep Sea Diver]

Any updates on this azalea?

Likely these leaves should be stripped off as a precaution. This will spur growth and increase ventilation.

cheers
DSD sends

 

[Knightlife]

I had this problem on an azalea and I just cut off all the leaves that had the problem. The next year it was no more

 

[lauralee]

Overall health looks pretty good to me. I do see folded-in leaves on the branch in the back. Are those folded up by a catterpillar? I woulkd check.
Usually, should be spread out and opened. Not folded in on themselves.

Yes, those spots are not good. It can be very hard to have an unblemished plant. Looks like it would fit under rust with a fungal cause.
H202 can do very little harm and could limit the spread.
I have many satsuki whose leaves get wet very often, and I do not see rust like this.
I also have less UV light than you so I should be seeing more.
Humid and windy should be good.
So check the spread and if H2O2 doesn't work, try something more potent like a fungicide.
I do not believe they present a risk to the health of the plant, just they look bad and may reduce vigor a tiny bit.

Can you suggest a suitable fungicide?

 

[Glaucus]

Can you suggest a suitable fungicide?

I am not an expert at all. Not sure what you would treat rust on azaleas with. More ventilation, more UV light, more overall plant health, may all be things that might be more effective in actually applying a fungicide.
But I do know that both chlorothalonil, difenoconazole and tebuconazole seem to be general purpose broad spectrum fungicides. The latter two being systemic.
But there are 100+ fungicides and depending on your location, some will be only available to commercial users.
For rust/pucciniastrum ssp. specifically, maybe mancozeb or oxycarboxin?
In the US, things like benomyl and captan may be available.

Recommending someone the right fungicide is like a complete profession. I'm just throwing out some compounds based off google and just some random spraying of plants.

 

[gxa]

Any updates on this azalea?

Likely these leaves should be stripped off as a precaution. This will spur growth and increase ventilation.

cheers
DSD sends

Indeed, I stripped all of those leaves.

What I've been noticing the last few weeks is that new leaves come out small, don't grow, and some end up having black tips.

I took the plant out of the plastic container and it have black areas that don't look good.

Maybe this is the background issue...

I am not an expert at all. Not sure what you would treat rust on azaleas with. More ventilation, more UV light, more overall plant health, may all be things that might be more effective in actually applying a fungicide.
But I do know that both chlorothalonil, difenoconazole and tebuconazole seem to be general purpose broad spectrum fungicides. The latter two being systemic.
But there are 100+ fungicides and depending on your location, some will be only available to commercial users.
For rust/pucciniastrum ssp. specifically, maybe mancozeb or oxycarboxin?
In the US, things like benomyl and captan may be available.

Recommending someone the right fungicide is like a complete profession. I'm just throwing out some compounds based off google and just some random spraying of plants.

This is useful information for me too.

Thank you guys!

 

[shinmai]

What’s happening in the pot may or may not be related to the leaf spots, but it’s a problem of its own. The black spots are deeply troubling, and appear to be root rot. I’ve also never seen green in a root mass like is visible in the photos. That almost looks like some sort of algae. You mention that you water every other day—watering on a fixed schedule is not a good idea. The tree should be watered when it needs water. I’m wondering if you are not letting the root mass get dry enough between waterings.

One distinctive attribute of satsuki is that they will not grow new roots in a pot with dead roots. If that is indeed root rot, the tree stops growing new roots while the fungus continues to consume and kill further until what living roots that remain are not sufficient to sustain the life of the tree. I have no idea how you would reverse that. Perhaps DSD has some suggestions.

 

[Glaucus]

Yes, those black roots are dead and need to be removed. Normal roots look yellowish-brown, sometimes very new ones can be white.
Looks like this one was in too small a pot and became pot bound.
Since you are in Spain zone 10, I would repot now, remove the bad roots, add new fresh kanuma. They will still have some time to grow new roots.
It is root rot in the sense of dead roots. Not in the sense of phytophthora killing healthy roots.
It can also explain the spots on the leaves.
If you have compacted soil, matted roots, or dead roots, then suddenly overwatering in kanuma can happen. Azaleas like it if their roots can dry out on overcast days when their leaves lose little moisture.
So you water when the kanuma starts to change colour to cream white.

 

[Deep Sea Diver]

Good eyes @shinmai Looks like the roots are dead and concur with @Glacus… don’t think it’s root rot as the tree would be dead at this stage.

Looks like the roots got too hot and died around the outside of the pot. This created organic material ripe for growth and successive watering allowed moss or some such to grow on the dead roots on the periphery of the pot.

Only seen this once before, but without the green.

As recommended before the outer roots need to be removed all the way around the pot sides and bottom. Follow the black and remove it until it’s all gone.

Compaction is not necessarily the cause of this situation. This sort of drying out can occur in extreme heat. In these cases the capillary action within the pot can accelerate the water transport in the rhizosphere to the surface. Extreme heat, coupled with normal transpiration can make this happen.

Likely this also caused the rust on the leaves, being wet most all the time.

But just in case, please take a thin rod, or piece of 3 mm wire and run it through the rootball top to bottom 1/2 dozen times…

If you’ve already repotted, you can do this while the tree is in the pot.

Aftercare. Water frequently… one can’t overwater a tree in Kanuma if the drainage is good. Every if things look dry during heat spells one can simply still the entire pot in water up to just below the rim until air bubble stop coming out. (Don’t let the Kanuma float away.)

The thing that is hard to figure out is how to keep this azalea healthy in such high heat. I have a friend down south who keeps his trees under ( I think 50% shadecloth) all summer and mists five times a day besides watering. Only morning sun to about 10ish depending on the heat. Bright to mostly full shade afterwards until the summer heat is past. @Chuah might want to add his experience to this advise.

It also might be a good idea to craft a styrofoam pot (with drain hole) to put around the pot during the extreme summers. This will really help keep the pot from heating up in your hot Spanish weather.

Rust… at this point I’d be more worried about the health of the tree and not want to nuke it with systemic. Dilute Hydrogen Peroxide ought to do the job and perhaps a small muffin electronics fan to keep the air flowing around the tree ought to do the job.

In any event, I’ll keep my fingers crossed for your tree. Please make update posts no matter what happens to the tree. It helps us learn too.

Finally I’d like to ask permission to use your photos for future use including a case study?

cheers
DSD sends

 

[gxa]

Hi, thanks very much for all of your feedback!

Finally repotted the Satsuki yesterday, I had to remove more roots than I would have liked.
When I took the plant out of the container the smell was too strong. The soil was not compacted though.
There were a lot of larger kanuma granules. Is that preferred? I only had medium-sized soil...

I hope to post a positive update in a while, I'll be praying to the bonsai gods meanwhile.

@DSD, feel free to use any of the photos in this thread.

Thanks!

 

[Deep Sea Diver]

Hi, thanks very much for all of your feedback!

Finally repotted the Satsuki yesterday, I had to remove more roots than I would have liked.
When I took the plant out of the container the smell was too strong. The soil was not compacted though.


——Good to know. Heat damage. The pot got too hot.


There were a lot of larger kanuma granules. Is that preferred? I only had medium-sized soil...


——Medium will work fine. Please don’t forget to use dilute Hydrogen Peroxide.


I hope to post a positive update in a while, I'll be praying to the bonsai gods meanwhile.


——That’s awesome!


@DSD, feel free to use any of the photos in this thread.

——Thank you. Vaya con Dios.

——DSD sends

 

[Glaucus]

I actually wanted to suggest to you that smelling the roots would be the best way to check for dead & decaying roots. Healthy roots should smell earthy, not smell like H2S / rotten eggs.
It seems that the combination of a small pot, a lot of heat, a lot of growth, and the roots desperately trying to find a way out of the container, created matted roots on the outside of the rootball, which then died.
Either of heat, overwatering, or lack of oxygen.
Matted roots like this is extremely common on azalea that grew well and rapidly. And it isn't an immediate health concern. Not completely convinced that these roots died because they were pot bound. But definitely things would have been better in a larger pot that was cooler and with more space for the new roots.

Small vs large kanuma particles is a bit of a niche debate. In general, small particles are probably better (2 to 5mm). The upside of the large particles (5 to 15mm) is that the satsuki can spend more time using it's roots to crush the kanuma particles. Meaning that if you put a large tree in small particles only, you need to repot every 2 years vs every 3 or 4 years.
The other theory is that with the large particles, you can create a bottom drainage layer, which is a controversial concept in itself. Generally, particle size is key for bonsai substrate. Sometimes more important than the actual material.
But it seems that for smaller trees and trees in development, the smaller particles are most ideal.
The third argument says you should mix all sizes. So then maybe 2 parts 2 to 5mm and one part 5 to 15mm. I am sure there's tons of debates on this subject on here. I will only join a certain camp after seeing scientific empirical data.

Smaller particles means more water and less air. Which may be more ideal for a zone 10 climate.

There are several brands and some of them offer sub 2mm size. But I have never seen anyone sell them abroad. So 'small' means 2 to 5 mm, which in general is ideal for small to medium sized bonsai.
If you have a huge tree, then for sure you'd mix in the 5 to 15mm.

 

[gxa]

Wow, that's a lot of useful information!
Thank you for the detailed response, @Glaucus.

 

[gxa]

Hey!

Here are pictures from today, 6 month after the emergency repot.

I think it's doing quite well, given its previous condition.

The pot is a bit shallow but it's the only non-plastic thing I had available.

 

[Deep Sea Diver]

Yes! Well done.

A couple thoughts

From now until after the tree blooms wouldn’t touch a thing, except remove old or damaged leaves and move the tea bags around to different spots every week to get even nutrition for the roots. Hopefully these contain low nitrogen or organic fertilizer.

Once the tree is done flowering do the standard cut back to two new branches two leaves…. and consider taking back the thicker branches to inner tree growth. Otherwise save beginning styling until next year.

You are correct, the Tokoname Training pot the tree is a bit too small. Yet the tree has little foliage so you ought to get away with the pot through summer. These are the correct pots used to grow azaleas, so look for perhaps one size up (number size is on bottom of the pot) to slip pot the tree inot this fall when the weather breaks. These pots get deeper with broader bottoms with each size up.

The normal growth rate usually calls for an up potting into the next size pot every 2-3 years at this size of tree. This will depend on the heathy and type of cultivar. Some grow really fast all the way to those that grow very slowly.

Not sure if the media is small or medium. If not small, when slip potting the tree use small and mix it in with the old media to help the tree retain more moisture. If the tree gets really dry quickly this summer, suggest also adding 10-20% finely chopped sphagnum. Soak it just before adding to the media.

cheers
DSD sends