Question - cool weather affecting listed zone 7 to 9 Chinese plants

Anthony

Imperial Masterpiece
Messages
6,290
Reaction score
8,232
Location
West Indies [ Caribbean ]
USDA Zone
13
Guys,

@Wires_Guy_wires ,
@Gustavo Martins ,

And anyone else.

Weather since November 4th has been around 65 to 69 deg.F [ 18.3 to 20.6 deg.C ]
and is continuing today. From 10 p.m until around 8 a.m.

The Chinese Serissa, the Gmelina and Fukien tea, in full sun are dying.

Those in the shade / dappled light are unaffected.

Any explantions ?

Normally our range is the low 70's deg.F [ 21.1 deg.C ] with one day
or so a week below in the 18.3 deg.C range.
Thanks in Advance
Anthony
 

Wires_Guy_wires

Masterpiece
Messages
3,062
Reaction score
4,601
Location
Netherlands
Anthony, some pictures would greatly help diagnostics.
Dying with yellow foliage, brown foliage, green foliage?


I always like these challenges! But it's hard doing these exercises without visual cues.
 

Anthony

Imperial Masterpiece
Messages
6,290
Reaction score
8,232
Location
West Indies [ Caribbean ]
USDA Zone
13
Guys,

ket me see what I can find, we have just been throwing them
on the compost heap.
Images I can show in a few days if I find any bodies intact.
Thanks for your patience.
Good Day
Anthony
 

Wires_Guy_wires

Masterpiece
Messages
3,062
Reaction score
4,601
Location
Netherlands
I can give you a list for general plant diagnostics that I've been wanting to write down for a while now. I'll see if I have time this week to start working on it.
 

Leo in N E Illinois

Imperial Masterpiece
Messages
8,383
Reaction score
15,574
Location
on the IL-WI border, a mile from ''da Lake''
USDA Zone
5b
When the sky is clear, no rain, it gets cooler at night. That is normally the signal trees from monsoon climates use to shed leaves and prepare for the dry monsoon. The period between wet monsoon, that has no rain. Are you sure they were dying, or were they just going dormant? The species you listed all come from areas with monsoon seasons.
 

Anthony

Imperial Masterpiece
Messages
6,290
Reaction score
8,232
Location
West Indies [ Caribbean ]
USDA Zone
13
Leo,

it was death, we did the bark / nail scratch test.
Suspect the roots being sensitive as the plants in the
dappled light shade were unaffected.

Also the ones in full sun until 11.00 a.m. seem to have
had enough time to cool back down by early evening.

Thought maybe the scientists would have had an easy
answer.

All the named species, in the ground or growing trough
are giving no problems.
Just the Bonsai pots.
Natives are just fine.
Testing mica pots as insulators.

Fortunately the dead are mostly small and not incredibly
important, though it is sad.
Thanks for responding.
Good Day
Anthony
 

Wires_Guy_wires

Masterpiece
Messages
3,062
Reaction score
4,601
Location
Netherlands
Well, based on what's written here, the only assumption I can do is that the temperature difference between full sun during the day, and cool temperatures during the night, might have stressed them out too much. 20 degrees C weather over here, means that clay pots can be 30 degrees C if they are in full sun. During the night, winds can help evaporation take place, which drops the temperature in the pots a few degrees C lower than the actual air.

In the shade it might be less of a difference. Because shaded parts usually get less sun, and less wind: less temperature variation.

But it shouldn't happen with temperature ranges like that, just a few degrees C. I've kept tropical plants outdoors at 2 degrees C for a week, and they're still alive and kicking after being placed in 30 degrees C. I'm asking for images because generally, plants tell a story through their foliage and trunks. It's easier to find a root cause with a story of the past. If the foliage stayed green, then it could be a sudden death. Especially in tropicals, and this would give us a lead to work with. If they turned color before the plant died, then it might be something else. From the color and progression of discoloration, we can tell a lot. As a matter of fact, I am so sure about this, that I once challenged my team to beat me in diagnostics of plant issues. They lost, 14 to 1. The 1 was an issue I had never seen before; iron uptake was blocked due to an overdose of antibiotics. The diagnosis was correct, but the team beat me with experience about the cause; they had seen this before and I hadn't. I figured iron was either not supplied, or blocked due to the medium having a pH that was too alkaline. It turned out the antibiotic blocked an iron pathway in both bacteria and fungi, as well as in plants. We had to switch types.

Summarized, all I know now is that plants in the sun died and plants in the shade lived, and that general temperatures are a little lower than usual.
Another possibility is, you're one of the few people in the world using compost. When temperatures get high enough for composting micro-organisms (MO's) to become active, but the plants stay dormant.. The MO's could cause issues because they'll start eating the tree that can't defend itself (trees don't fight very well in the cold, but bacteria do!). If that happened, the roots will be soft and the bark of the roots will come off easily and slimey. But since that's part of the natural break down process as well, it should be checked first before running other options. Otherwise you can't safely tell if it was natural because it was a dead tree degrading, or that it happened because of something actively feeding off of the live plant and killing it.

Things we can confirm or rule out with visual cues:
- Pathogens - possibility, shown on trunk and or foliage.
- Temperature issues - possibility, shown on foliage and general state of the entire plant.
- Watering issues - possibility, shown on foliage.
- pH or nutrient issues - unlikely, shown on foliage.
- Salt buildup issues - can be a cause, in the sun you have to water more often, shown on trunk and roots and foliage.
- Disease - viral, possibility, shown on the foliage.
- Other factors like animal damage or dogs peeing all over the plant - shown in foliage, roots or trunk.
- Antibiotic over use - unlikely because you're not the type.
- Other things I can't think of right now.

I'm working on the document on how these cues work as we speak. But you can assume it's going to take another week or two before it's finished.
 

Anthony

Imperial Masterpiece
Messages
6,290
Reaction score
8,232
Location
West Indies [ Caribbean ]
USDA Zone
13
Guys,

only our Pines are in porous earthenware pots.
Unaffected.
Everyone else is either vitreous clay or plastic bonsai pots.

Winter High is the lower 80's deg.F [ 30 deg.C and under ]
plus it is only held for 30 to 15 minutes.

The real change is the lows, never seen so many before.
Normally goes low for once or twice a week.

Plants were pot bound, ready for repotting 2nd Jan.
as we normally do, no root destruction.
Will see about taking to the University for root examination.
May take months.
Thanks for taking the time to respond.
Anthony
 

Gustavo Martins

Chumono
Messages
847
Reaction score
1,091
Location
Azores
No idea Anthony. I don’t have or know those species but I personally don’t bite the temperature change scenario. All my tropicais spend the entire year outside and I get much colder than you. All are fine. I believe it’s something else, but not sure what.
 

Forsoothe!

Masterpiece
Messages
3,992
Reaction score
4,706
Location
Michigan
USDA Zone
6b
I don't know much about Fukien Tea's native range, but I keep my single plant in cooler dappled sun in my greenhouse and the soil always basically damp, here at 42.6°N., I can't imagine it in full sun of the tropics?
 

0soyoung

Imperial Masterpiece
Messages
6,661
Reaction score
10,898
Location
Anacortes, WA (AHS heat zone 1)
USDA Zone
8b
No idea Anthony. I don’t have or know those species but I personally don’t bite the temperature change scenario. All my tropicais spend the entire year outside and I get much colder than you. All are fine. I believe it’s something else, but not sure what.
I don't have tropicals, but had a serious dose of this problem myself a few years ago. Gotta water. It may seem overcast and humid, plants are 'dormant' but once roots are dry one has a dead plant. It happened especially to stuff I had in the sun.
 

Anthony

Imperial Masterpiece
Messages
6,290
Reaction score
8,232
Location
West Indies [ Caribbean ]
USDA Zone
13
0soyoung,

no there was no drying out. Plus at this time of the year, the trees
that need repotting are pot bound. Need water.
So after Christmas the cycle of 1 in the evening, and two in the
morning re-starts.

Plus we have plants set at points that wilt rapidly.
Indicators.
Humidity got to as low as 45%.
We get from Christmas until June, high winds.
Thanks for replying,
Good Day
Anthony
 

Anthony

Imperial Masterpiece
Messages
6,290
Reaction score
8,232
Location
West Indies [ Caribbean ]
USDA Zone
13
Okay Guys, think I got the answer.

Years ago, we brought up some Tamarind seed from a 150 year old or
so Tree,
This was south Trinidad on the beach.
Temperature is 90 - 88 by day and 75 - 80 deg.F by night.
[ 32.2 - 31.1 deg C ] [ 23.9 - 26.7 deg.C ]

Central and North Trinidad for whatever reason has the same high
but goes cooler 70 to as low as 64 deg. F at night.
[ 21.1 - 17.8 deg.C ]
The front yard where the growing trough is, is asphalted and faces west.
Stays warm all year long.
Not so the windy. lawn/ trees back yard.

Anyhow, the tree grew well and when they were close to 3 inches, trensferred to
plastic bonsai pots, [ 8 cm ]
When they were transplanted next year on the 2nd of January, 2 died.

Asking on IBC, the Filipinos, suggested April / May.
So we split the repotting into sessions. January and April/May.

Just checked three Serissa s, and they are next to the asphalt.
They are fine and the pots are 1 inch [ 2.5 cm ] deep.
So it maybe some form of root sensitivity.

Let you know what the University says.
Thanks again all.
Anthony
 

Forsoothe!

Masterpiece
Messages
3,992
Reaction score
4,706
Location
Michigan
USDA Zone
6b
I hate to be the skunk at this party. But then, maybe a skunk is needed. The kinds of temps being thrown around are... pleasant, not terminal. My greenhouse on the worst days of winter occasionally get down to ~low 40's°F when the outside gets below 10, and spend a lot of time in the low 50's. My plants don't like it, but they don't die, either. 60 overnight is pretty typical for 4 months. I have Kyoto Serrisa that look like crap in winter, losing all the leaves by ~December, then limping along with some petty foliage growth that only just the last couple weeks is showing real growth, which is a typical year, but the Fukien Tea always looks pretty good all winter as long as it doesn't get too much sun/heat. Anthony, if your same species is dropping dead, it must be for different reasons. I sure as hell don't know what the problems are, but coolness ain't it from my experience. But then, what do I know? Mine are never dry.
 

kevinlovett86

Chumono
Messages
821
Reaction score
1,100
Location
ShenZhen, China
USDA Zone
10
@Anthony
Meanwhile in the Middle Kingdom, all the Fukien tea trees aren’t missing a beat, my own is in a tiny mame pot, so it doesn’t see a lot of sun, it’s actually flowering at the moment. However, as for the hedge and topiary trees, they can’t be moved, and temperatures are steadily climbing on this side.
E84A7116-7E2F-4374-AFA7-4C759C0568D1.png
Hope you get to the root of the problem though.
 

Shibui

Masterpiece
Messages
2,465
Reaction score
4,655
Location
Yackandandah, Australia
USDA Zone
9?
The only one of those species I grow is Serissa. I thought it was supposed to be cold sensitive but all mine came through our winter alive. Some looked a little sad at times but have bounced back and growing strong again this summer. 1 older one in a largish ceramic bonsai pot. All others are younger cuttings in 4" plastic nursery pots. All in the open and subject to the full cold of our winter nights. Min temps last winter down to freezing most nights for 3 months with one night down to -6C.
I don't think temp is your culprit.
I would reconsider the pot bound issue. No matter how well you water severely pot bound trees the water just cannot penetrate into the centre of the root ball while the tree continues to take water and the root ball gets drier and drier each day until not enough to sustain the tree through a day. I have experienced this and have found this through autopsy of deceased plants. Outer part of the root ball was damp but the centre was bone dry despite what I thought was adequate watering and dead tree not taking any water.
Another possibility is the soil mix. I know you think yours is good but many others have moved to different soil mixes for good reason.

Need to keep an open mind to all alternatives.
 

Anthony

Imperial Masterpiece
Messages
6,290
Reaction score
8,232
Location
West Indies [ Caribbean ]
USDA Zone
13
Kevin,

we have gone drier and drier with more breeze.
Which is normal for us until May/June.

Shibui,

if the soil has the red brick, it is impossible to go dry.
Plus watering in the evening allows the tree's soil to
re-moisturize over night.
The two passes in the morning will fully re-wet.
There was no wilting.

Before fertilising, the soil in the evening is pre-wetted,
if the soil goes dry during the night, it will repel the
water.

Plus with the finding of 3 that had no damage, more
or less explained it.
However a trip to the University will be made for the
scientists there to take a look,
Thanks for responding you two.
Good Day
Anthony

* We water by watering can and not the hose.
 

Mellow Mullet

Masterpiece
Messages
3,486
Reaction score
8,867
Location
Mobile, Alabama-The Heart of Dixie
USDA Zone
8-9
Upper Sixties is not too cold for serissa, I leave mine out pretty much year round, only bring the double flowered one inside, if it freezes, as it is more cold sensitive that others. But they all see temperature fluxuations during our wild winters in Mobile of anywhere between the upper thirties to the upper seventies, so I seriously doubt the temperature has much, if anything to so with it. I think it has more to do with full sun, if I leave mine out in full summer, direct sun all day, they do not do well and I will get dieback, you mentioned that the ones in dappled shade are doing well, so there is a clue. Also, serissa are very picky about water, if you keep them too wet, the roots will rot and they will die. I suspect it is a combination of direct sunlight and too much water.
 

Anthony

Imperial Masterpiece
Messages
6,290
Reaction score
8,232
Location
West Indies [ Caribbean ]
USDA Zone
13
Thanks Mellow Mullet,

well luckily, the healthy survivor is in a Chinese glazed, porous
bottom pot.
Handles the watering well, and sun is until 11 to 12 a.m.
Will watch that more closely.

The Japanese form dies down here after around 4 years,
which is the sign for us of needing cold.
Don't grow those anymore.
Much thanks.
Anthony
 

Wires_Guy_wires

Masterpiece
Messages
3,062
Reaction score
4,601
Location
Netherlands
You repotted them recently, do I understand that correctly?
If so, it might be a pathogen thing cross-contaminating from the tools or the soil.
If you throw sick and/or dead trees on the compost pile, and you get your compost from the same pile.. Well, that would explain a lot!

One of the most common soil bacterium, Bacillus subtilis, can survive boiling water, pH shocks and even short blasts of X-rays. It will survive a compost pile. As will many pathogens.
But again, it's hard to say without visual cues.
 

Similar threads

Top