Moisture stress?

[Katie0317]

I was reading about changes in leaves during the heat wave we've been having and I kept running into the term 'moisture stress'. I looked it up and it's complex. Does anyone understand it and is able to explain it in a way that's easier to understand?

Moisture stress - Wikipedia

en.wikipedia.org

 

[sorce]

You shouldn't be concerned with "moisture stress" as long as you have your pot watered.

Then you're left with just "heat stress" which will be a different thing to be concerned with, though I consider that concern minimal, it's either @Fidur or @Clicio (I been confusing them lately) who has some good data on shade cloth temperature changes which may prove useful.

In all, water, and you are safely outside of the 2 minute death window that is underwatering, and into the months long death window that may be "overwatering" if it exists.

Further, hell with that poorly written Wikipedia article, it's confusing!

I always travel further down the good info search, until things like this appear.

I have a hard time following the accent, but the information should be better than the wiki article.

Sorce

 

[Fidur]

Hi Katie, I'm sorry I know nothing about moisture stress...
All I know is that when a heatwave occurs (and we are currently under one of them) , my cloyh shade combined with my low pressure misting system are able to drop the temperature up to 10ºC (and up the humidity to 85-95%).
My most "fragile" (maples, dawn redwood, fukien tea,....) and really none of my species suffer any damage in these heatwaves....

 

[Clicio]

I put them under 50% shade cloth, and water them twice or three times a day.
It works.

 

[Katie0317]

We're in the midst of a severe heat wave with the heat index over 100 degrees. My husband installed a shade sail which blocks 80 percent..It blocks overhead sun but when the sun is low it can't block that. I was out this morning and just standing there for ten minutes it was blistering hot. Not all the plants fit under the shade sail but that's okay because some of the tropicals love full sun. BRT's, crape myrtle, and a few others are happy with the sun beating on them all day but others show the stress.

I can't imagine if he hadn't had the foresight to install the sail. That's been a saving grace.

 

[Clicio]

Hi Katie, I'm sorry I know nothing about moisture stress...
All I know is that when a heatwave occurs (and we are currently under one of them) , my cloyh shade combined with my low pressure misting system are able to drop the temperature up to 10ºC (and up the humidity to 85-95%).
My most "fragile" (maples, dawn redwood, fukien tea,....) and really none of my species suffer any damage in these heatwaves....

@Fidur Could you please explain how your low pressure misting system works?
I am researching one solution myself.

 

[Katie0317]

Hi Katie, I'm sorry I know nothing about moisture stress...
All I know is that when a heatwave occurs (and we are currently under one of them) , my cloyh shade combined with my low pressure misting system are able to drop the temperature up to 10ºC (and up the humidity to 85-95%).
My most "fragile" (maples, dawn redwood, fukien tea,....) and really none of my species suffer any damage in these heatwaves....

I'm interested in hearing about your low pressure misting system also.

 

[Fidur]

I bought a 12 meter low pressure system:
https://es.aliexpress.com/item/1005..._list.0.0.1cf3194daKlDUh&gatewayAdapt=glo2esp

Then I attached it to my shade cloth and connected to my garden hose:



I also have three temp and humidity sensors in different parts of my bonsai garden. When I'm inside I monitor those sensors in a panel, and whenever I see temps growing (or humidity lowering) I turn it on for 5 to 10 minutes and everything comes under control..... (I'm sorry those pics were taken in midday and misting can't be apreciated, but in them the system was working)

 

[Mike Corazzi]

I'm interested in hearing about your low pressure misting system also.

Misting can bring on mildew and fungus. Be careful.
The only time my LEAVES get watered is when the sun is OFF of them and it's hot enough for just air movement to dry them.
IOW I water from above the first time each day and then maybe around 4PM when they're in shade but it's still 8,000 degrees temp.

Also my overhead watering follows immediately after I have watered the pots normally.

 

[Dav4]

I'm just going to mention a few things from personal experience. "Heat index/feels like temperatures" and "wind chill" are human constructs to explain how a person might feel hotter or colder in a given climate with certain parameters... the thing to realize is that it doesn't really apply to plants. If anything, higher ambient humidity and the subsequent increase in the heat index actually lowers transpiration needs. Throw in mid summer heat dormancy, when trees slow down metabolically due to consistently high temps, and water needs might actually lessen. This time of year in N GA, I'd find the soil in many of my trees wasn't drying out like it may have 6 weeks earlier. I'm actually watering more this summer in MI then I did last summer in GA because the relative humidity is lower but temps are still in the 80's and 90's and the trees are more active. Anyway, shade is good in mid summer for sure for sensitive trees and just because it's extremely hot and humid doesn't mean you need to water more... check the soil, first.

 

[Fidur]

Misting can bring on mildew and fungus. Be careful.
The only time my LEAVES get watered is when the sun is OFF of them and it's hot enough for just air movement to dry them.
IOW I water from above the first time each day and then maybe around 4PM when they're in shade but it's still 8,000 degrees temp.

Also my overhead watering follows immediately after I have watered the pots normally.

I only use this device in summer and under a heatwave. This is the third heatwave since june. I'm always very attentive to those kind of problems and I haven't experimented any mildew or fungus. In fact my maples are sprouting and growing fast and fine after the last month pinching.....
Also, I'm not advising this to anyone. It just works for me in my circunstances.

 

[Clicio]

I'm just going to mention a few things from personal experience. "Heat index/feels like temperatures" and "wind chill" are human constructs to explain how a person might feel hotter or colder in a given climate with certain parameters... the thing to realize is that it doesn't really apply to plants. If anything, higher ambient humidity and the subsequent increase in the heat index actually lowers transpiration needs. Throw in mid summer heat dormancy, when trees slow down metabolically due to consistently high temps, and water needs might actually lessen. This time of year in N GA, I'd find the soil in many of my trees wasn't drying out like it may have 6 weeks ago. I'm actually watering more this summer in MI then I did last summer in GA because the relative humidity is lower but temps are still in the 80's and 90's and the trees are more active. Anyway, shade is good in mid summer for sure for sensitive trees and just because it's extremely hot and humid doesn't mean you need to water more... check the soil, first.

Dave, summers here are out wet season. Usually it rains every afternoon and temps are near 100f, which means high heat AND humidity.
My bonsai under shading cloth gets watered twice a day during the whole summer season. Yes, I usually avoid watering the leaves after 5pm, but it can always rain during the evening.
But we don´t have many problems, as mildew and fungus are rare because the hot air usually dry the leaves and branches pretty fast.
Junipers and pines and tropicals are usually under full sun, and get watered mostly on the soil. Junipers like some misting on their green mass though.
Yes, we do expect summer dormancy for some species, and water requirements are indeed lower for those trees.

 

[Katie0317]

Misting can bring on mildew and fungus. Be careful.
The only time my LEAVES get watered is when the sun is OFF of them and it's hot enough for just air movement to dry them.
IOW I water from above the first time each day and then maybe around 4PM when they're in shade but it's still 8,000 degrees temp.

Also my overhead watering follows immediately after I have watered the pots normally.

You're right. I live in the subtropics and with the heat and humidity plus a tremendous amount of rain...I don't need to be misting. It sounded like a good idea but I'd be adding fungus to the mix if I starting misting.

In the part of Florida where we live there aren't seasons like there are in most of the country. It's hotter than blue blazes for 6 months of the year and when other people are experiencing winter, it's finally heavenly here. We can open all our windows and doors and it's beautiful, but the summers are rough.

Thanks for reminding me...Misting is out of the question in the summertime and unnecessary in winter.