Azalea-wars 2 Determining Signs of Trouble - From an inquisitive person

[Deep Sea Diver]

Greetings Azalea Folks!

For years BNutter advisors have been sharing information to folks on this site about azalea issues. Specifically concerning leaf signs indicating under and over watering, sun burn and over fertilization. In this thread I decided to experiment to see just exactly what these different issues look look like.

In each trial the set up involves using two nursery satsuki azaleas. The trials were a bit tricky as it was my desire to initiate the initial signs of trouble, yet not to kill the azalea…. to be able to restore it to robust growth. This would yield information on both what the signs were and how to bring the azalea back to a healthy state.

A bit of a sticky tightrope, which proved to be a real challenge.

- An old satsuki cultivar “Beni Kirishima”,


- The second is azalea marketed as a satsuki “Buccaneer”. Buccaneer is supposed to be a Glen Dale hybrid that looks like the flower photo on the left below, but this azalea flowers like the photo on the right. Hmm. Oh well, nursery folks often produce azaleas and just give these catchy names when marketing the plant, without registering it. Maybe this is one of these

Glen Dale Buccaneer Here’s the test subject flower


Anyways these are the two test subjects referred to for each trial in this thread.

Cheers
DSD sends

 

[Deep Sea Diver]

Experiment One - Underwatering

Trial A - Beni Kirishima

Technically underwatering should cause the root cells to slow or stop the flow of fluids up the azalea trunk, causing the leaf tips, the furthest point away from the roots, to first get less or no water. The literature says this is initially shown when the tips of the leaves, short of water will brown.

In this trial Beni Kirishima behaved by the book.

Given little to no water for three weeks Beni Kirishima’s leaves began to look like this:
…. and progressed to look like this.

Note the top tier of leaves browned out as expected. At this point I submerged the entire root ball in a bucket of water. Once the peat begin to get wetted, pushed a wire through the rootball multiple times to allow the water to penetrate into the shin.

Three weeks later Beni Kirishima looks like this:




Note the top tier of new leaves are green and the plant is showing definite signs of recovery.

Next post - Experiment One - Trial B- Underwatering Buccaneer - another warning sign appears.

cheers
DSD sends

 

[Carol 83]

I think this thread will be very helpful for those of us fairly new to azaleas to troubleshoot issues.

 

[Godschick]

Thanks for doing this DSD. I have one azalea currently that is struggling a bit here and there. This will certainly help me with troubleshooting and to see if I want to continue to add more to my collection.

 

[Glaucus]

I feel like there are two behaviors for underwatering. 1) leaf tips get burned 2) Entire shoots wilt.
Seems like the first one occurs on more mature stronger plants, as a defense mechanism. The plant is able to retain water, except for the leaf tips.
Younger shoots, seedlings, cuttings are more prone to having an entire shoot dry out, without any burned tips.

Another behavior I have only observed on two azalea that are in kanuma, is that the tips get black. Not sure what this is. Only the most outermost margins become black.
I can't see how it can be something else than underwatering. Not sure why this would become black, though.

Note that azaleas can dry out, become completely exfoliated, and bounce back. If they are mature plants.

I have a bunch of azaleas with different types of damage and unusual responses. Not entirely sure what all of them are.
Even a funny one of an azalea seedling that likely had too much shade.

Will be interesting to see your overwatering result.

 

[Deep Sea Diver]

Experiment One - Underwatering

Trial B - Buccaneer

When Buccaneer was not watered at all, as per trial A, a surprising result occurred. Surprising as what happened is rare in my experience. (Just to clarify all study subjects are the same age.… likely about 5 yoa)

After about ten days Buccaneer began to wilt at the growing tips of the foliage. In the past I’ve always seen this as a sign of root rot.




After the growing tips wilted I submerged the plant and attempted to rehydrate it in the hope that rehydrated, the leaf tips would brown as Beni Kirishima. This did not happen. Instead the leaves fully rehydrated!

Hoping another round of drying might show brown tips. So Buccaneer was dried again. Here’s the result….


Same result…

Finally I decided to dry the azalea even more, perhaps risking damage, in hopes tip browning would occur. Sadly the azalea merely wilted more and more. August 2nd, 2022



At this point plug was pulled on the trial the plant was in grave danger of dying. The root ball was rehydrated once again, but the leaves wouldn’t respond. Officially in the ICU now. August 17, 2022

The wilt continued. I snipped off some branches and these were still green. Today Aug 22, 2022, I topped Buccaneer. All top leaves are dry, so it was cut back and the cuts were immediately sealed. Still green inside the stems. It’s in critical condition.



What did I learn from these two trials?

There are at least two signs indicating under watering in azaleas. Browning leave tips and wilting of growth areas with no partially brown leaf tips.

Buccaneer can come back from drying conditions as long as one waters when the growing tips are wilted… but likely not from further drying.

Could the wilting tip symptom possibly be confused with root rot? I don’t know. The next experiment may answer this question… or not.

Cheers
DSD sends

 

[Glaucus]

Ah, then you got both results as well. Did Buccaneer have more new growth than Beni Kirishima?

 

[Deep Sea Diver]

Sorry. I didn’t cover that. All plants were selected to have the same perceived distribution of foliage and robustness….

There were over 40 of each to select from.

Cheers
DSD sends

 

[Deep Sea Diver]

Aftermath Experiment One - Underwatering

Trial A Beni Kirishima. Good news! After weeks of TLC this azalea is well on the roars to recovery. It took a linking and kept on ticking!

Macro view. Micro view


Trial B - Buccaneer - Bad news! This normally robust azalea flat out gave up the ghost. Not surprising after the mishandling it experienced.

Macro view. Micro view


There is more data. Roots. Let’s look at the rootballs, along with that of a healthy 3” pot Chitosegawa satsuki

Beni Kirishima. Buccaneer. Chitosegawa


(Both root balls are moist.) Buccaneer’ roots are definitely not looking good….darker brown compared to Beni Kirishima. Chitosegawa‘s roots seem just a bit lighter then Beni Kirishima.

Well that’s the data from this test.

Summary: There appear to be at least two signals to signal an azalea needs water. Nodding growth tips and drying leaf tips.

Buccaneer’s underwatering signal shows sooner and is striking. Nodding growth tips can get one’s attention at a glance. Recovery is swift… overnight… until one goes “too far”. Extended drought kicks the plant past the point of return.

Beni Kirishima’s underwatering signal takes longer to appear, slowly becoming evident on some leaf tips. Then expanding until the drought stops. Recovery is much slower, touch and go for multiple weeks. Even then, the leaf tips will never look normal again this year.

Cheers
DSD sends

Next event - Experiment Two Overwatering!

 

[Bonsai Nut]

I love threads like this! I read through it twice just to make sure I understood everything that @Deep Sea Diver was doing - and the results.

 

[Deep Sea Diver]

Experiment Two - Over Watering - Trial One - Buccaneer

In this experiment the same two Azalea cultivars were used, Beni Kirishima and Buccaneer.

The goal was to document overwatering signs and possibly trigger root rot. I know personally it can be hard to trigger root rot if an azalea is planted in well draining media.

BACKGROUND. So this is a bit of a challenge. Both azaleas are in decently draining peat, perlite and bark. Short of repotting the azalea in poor media, potentially triggering other issues, I needed to do something that goes against my better nature and actually set out to damage the azaleas!

The issue is if one gets Phytophtora Root Root,and Wilt the azalea is toast and has to be thrown out so this fungus doesn’t spread throughout the garden. The critter causing the damage is P cinnamomi Rands, which can be found in most places in the world. It can hide out in the soil for long periods of time during its resting stage before it strikes. An azalea can be treated to look healthy once infected, but unless all of the pathogen is totally destroyed once overwatered P cinnamomi Rands will flourish again and this time attack an already weakened plant

SYMPTOMS: Usually the entire plant begins to wilt at once. The first symptom is slow wilting and bronzing of the foliage with possibly some browning of the basal portion of the stem of the plant. Finally the entire plant turns brown and the leaves fall off.

SET UP July 3rd 2022. Both azaleas were placed in buckets covering the majority of the rootball. The bucket was filled with water. Afterwards, each azalea was watered on a regular basis.

Here both are in their respective buckets, Buccaneer on the left, Beni Kirishima on the right.


August 2nd. Thirty plus days later.

Buccaneer has definitely attained all the symptoms of Phytophthora root rot and wilt. The entire plant is degraded, showing bronze leaves, overall loss of turgor. Younger areas are wilting the most.



The plug was pulled on this trial. Buccaneer was pulled out of the water, treated with 3% Hydrogen Peroxide, diluted to 1% in an effort to halt the symptoms for five minutes and flushed. (Even as Buccaneer was destined for the trash, I felt it was worth a try!)

September 2nd - final entry. Buccaneer Final Entry

The azalea continued to degrade, showing further bronzing, wilting then drying out. At this despite intensive care…drying the rootball to barely moist, misting the leaves and carefully spaced out light watering.



Buccaneer is toast! It will be disposed of in the garbage.

Next - Experiment Two - Trial Two - Beni Kirishima …Will Beni K follow suit?

cheers
DSD sends

 

[Prickly_pair]

Thank you DSD for these experiments. As a relative newcomer to Satsukis any information I can glean is very welcome. I wait with baited breath for the final results.

 

[Deep Sea Diver]

Welcome Aboard! No worries Exp 2 Trial Two will be posted soon.

btw there is an ever growing body of satsuki and other azalea knowledge posted on this website. Try the search function for azalea, Satsuki to get you one the right path. Plenty of folks here work azaleas try @Glaucus, @Pitoon @Mellow Mullet @Shibui @Leo in N E Illinois for starters.

cheers
DSD sends

 

[Prickly_pair]

Thanks DSD. I'll search for more info.

 

[Deep Sea Diver]

Experiment Two - Overwatering Trial Two - Beni Kirishima

In the first overwatering trial Buccaneer appeared to ’successfully’ get Phytophtora Root Rot and Wilt (that’s an oxymoron for sure!) or more scientifically, infected with P cinnamomi Rands.

While not totally sure this was the specific fungi involved, Buccaneer showed the classic symptoms of Phytophtora Root Rot and Wilt. Systematic degradation, bronzing of the leaves, overall loss of turgor leading to the elite plant wilting.

Thus one could fully expect Beni Kirishima to follow suit…. or not?

Here’s both Buccaneer and Beni Kirishima side by side before the experiment started…. and their respective flowers.

Buccaneer Beni Kirishima.

…again at start of the experiment July 3rd. Buccaneer in front, Beni Kirishima in the rear (silver bucket).



August 2nd. - There is no apparent change on Beni Kirishima besides the yellowing of a few old basal leaves.
Buccaneer had already showed obvious signs of root rot and wilt by this time.



September 2nd - An unexpected result. Buccaneer had given up the ghost by now. In contrast, Beni Kirishima shows little to no obvious signs of root rot and wilt. Still some old yellow leaves. There was some new growth down low that was brighter colored, possibly choloritic, not unexpected though…. No bronzing, loss of turgor or systemic wilt apparent.



As you recall Buccaneer had given up the ghost by now. But Beni Kirishima has little to no external signs of root rot and wilt.

Perplexing. Lets take a look ‘under the hood’ at each azaleas roots, and again comparing with a healthy azalea, this time Nachi no Tsuki

Buccaneer. Beni Kirishima Nachi no Tsuki


Close examination showers Buccaneers roots are browner, while Beni Kirishima’s roots appear lighter, even yellow white in areas. Beni Kirishima roots appear similar to the healthy Nachi no Tsuki roots.

At this moment I felt more than a bit perplexed. Why didn’t Ben Kirishima get Phytophthora Root Rot and Wilt?

Diving into my resources. I came up blank until ….paging through Galle’s Azaleas I found what might be the answer! It was in a Data Table, with no explanation. The data table showed the Response of Azaleas to Innoculation with

 

[Ugo]

Hey DSD!

Please tell us the end of the story!!

 

[Deep Sea Diver]

… Sorry @Ugo I ran out of time to edit! Here’s the missing piece

At this moment I felt more than a bit perplexed. Why didn’t Ben Kirishima get Phytophthora Root Rot and Wilt?

A likely explanation. Diving into my resources. I came up blank until ….paging through Galle’s Azaleas I found what was the likely answer! It was tucked away in a Data Table, with no explanation. The data table shows the Response of Azaleas to Innoculation with P. cinnamomi*

The data table displayed the results of purposefully inoculating different evergreen azaleas with Root rot fungi! After trying to give a number of azalea cultivars root rot, (not all, of course!) the researchers discovered certain cultivars are resistant to root rot.

Of the 19 listed as resistant there were four satsuki’s Eikan, Pink Gumpo, Higasa and Shinkigan. There were also some listed as moderately resistant: Amagasa and White Gumpo

From these data I infer Beni Kirishima appears to be one of the rarer cultivars resistant to Phytophthora Root Rot and Wilt cultivars. At least if submerged in water less then or equal to 60 days! .

Summary: Well, what did I learn.

1. Most evergreen azaleas, including Buccaneer, are susceptible to root rot.

2. A small number of cultivars are resistant to root rot, including Beni Kirishima. Beni Kirishima’s performance in the trial showed strong resistance. (Also there may be more cultivars resistant that were never tested.)

3. Choosing Beni Kirishima was a fortuitous choice of study subject. Otherwise we might of ended up with two cultivars showing the same result and not discovered there are root rot resistant cultivars

4. Finally, root rot can be controlled, but not completely eradicated. It can spread easily from plant to plant via water flow. So it’s best to dispose of the affected plant in the solid waste, not compost.

….and that’s all folks!

cheers
DSD sends

* Galle’s Data Table source: Benson, D. M. and F. D. Cochran. 1980. Resistance of evergreen hybrid azaleas to root rot caused by Phyotophthora cinnamomi. Plant Disease 64: 214-215.

Next: Experiment Three - Over fertilizing trials

 

[Glaucus]

Thanks for trying this experiment. I have not seen many pictures of azaleas with root rot caused by Phytophthora.
The study on root rot in Rhododendron spp. is here: https://scholar.lib.vt.edu/ejournals/JARS/v34n4/v34n4-benson.htm
Sadly, they do not fully report on the statistical significance of their results, which they easily could have since they had a large sample size.

Satsuki having some natural resistance makes sense, as in their native environment, they experience flooding and possibly also standing stale water.

I would say that if people post pictures of azaleas that are not looking too well, they rarely show signs of root rot like this one.

I don't know if you want to do more experiments. But one would to try to reproduce some symptoms I see, which I will post later in my own thread.
And one where an azalea doesn't get enough light.

 

[kekoa]

The results of your experiments are a great help for a novice such as myself! So much online guidance is like brown leaf tips... well could be a sign of overwatering, underwatering, overfeeding, or perhaps underfeeding Thank you for sacrificing these plants for science and learning!

 

[Deep Sea Diver]

Experiment Three - Over fertilizing trials

Once again this experiment featured both Buccaneer on the left and Beni Kirishima to the right.



These are two azaleas that have proven to be hardy in the past… although from the previous experiments Buccaneer seems to be more of a Shrinking Violet, it ain’t so. I’ve numerous Buccaneers in pots and in the ground. They are good goers, hardy and reliable, brilliant flowering satsuki. Yet if you severely mistreat them, Buccaneer will resent this.

In this test both azaleas were given double doses of Osmocote Plus supplemented with liquid Miracid/Humic acid/kelp fertilizer every two weeks.

Then we watched and observed. …The azaleas flourished. Four weeks later another dose of Osmocote Plus was added. Liquid fertilizer was raised to 5x normal dose and administered weekly.

August 27 2022 - Leaves begin to change color.

Buccaneer. - Top foliage shows discoloration



Beni Kirishima - Leave tips start to lose green color.



September 2, 2022 there was more damage shown

Buccaneer - Loss of color on top foliage



Beni Kirishima - widespread color loss on most leaves, especially on one of the two plants in the container.



So definite damage is being shown. It was time to put the brakes on this experiment! Both pots were inverted and all Osmocote Plus removed. Then both were flushed to remove excess liquid fertilizer. Each pot was chocked up to dry quickly.

Now it’s time to wait and observe to see if these trees will recover…

Next Post - Wrapping this experiment up.

Cheers
DSD sends