Watering potted mango trees

[wslau]

Hello All.  Happy Thanksgiving!

I have enclosed a picture of what I believe is the result of overwatering for a potted mango tree.  I have read posts elsewhere that the symptoms of overwatering and underwatering are similar ....resulting in browing tips of mango leaves.  Is this true?


I have shown the front and back sides of the 2 leaves from a 15 gallon potted Mallika mango tree in Southern California (SoCal).


The moisture meter [Hampton Bay three way (moisture, light, pH) conductivity 9 inch probe] is 6/10 after yesterday's watering, which means that it is very moist, but not wet.
My friend and I debated whether these meters are accurate.
On another post, CTMIAMI stated
"The only real accurate moisture indicator is a Tensionmeter. That is what I use, after spending hundreds of dollars is others over the years."
I'm thinking about this $100+ investment.

Mimosa Los Angeles (LA), where the Mallika mango tree was purchased, told me that their [Southern California] potted mango watering guidelines are:
Summer:  Water every 5 days (3 if extemely hot).  Fill it to the rim (2-3 inches of water) once.  Let it drain fully.  Fill it to the rim a 2nd time.
Winter:  Water every 15 days.  Fill it to the rim (2-3 inches of water ) only once.

I didn't ask for any advice for Fall or Spring watering...
so I interpreted Fall and Spring as water every 5-7 days, filling it to the rim (2-3 inches of water) only once....perhaps less after looking at my pics?
Sometimes it is harder to estimate this if the potting soil is filled high to the rim like mine is.
But I probably should switch to the winter watering schedule now that nighttime temperatures in SoCal will drop below 50degF really soon.

Any opinions?

Warren

[KarenRei]

What kind of moisture meter are you using? Anything that works simply on raw electrical conductivity of the soil (aka the vast majority of them) are not very good, as conductivity is also affected by soil airspace, electrolyte levels, etc. And even a good meter is limited to the part of the pot it's in.

Were the watering guidelines you were told for your specific mango situation - a mango the size of yours in a 15 gallon pot with your soil mix - or were they generic / for something else? Watering frequency varies as much by planting conditions as it does by species.

As a general rule, yes, the symptoms of both underwatering and overwatering are very similar, which is unfortunate. Overwatering causes root rot, which means the roots can't get water to the leaves. So either way, overwatering or underwatering, you get the same leaf symptoms. The difference is in the roots; overwatered roots are brown, degenerating, and in bad cases with other symptoms such as infestation by decomposing insects or with a bad smell (literally, rot). But you have to dig up roots to examine them.

Mangos are root-rot sensitive - they like airspace in their soil. They generally won't tolerate the soil being kept continuously moist. Of course, they don't tolerate the soil getting bone-dry, either - you have to strike a middle ground    A good soil mix, with coarse grainy and inorganic elements (the oft-mentioned "gritty mix") will give you more leeway for imperfect watering than a poor drainage / less porous mix.

[swfruittreeaddict]

My experience has been overwatering will cause leaves to yellow and drop, under watering will cause the leaves to curl.

[bangkok]

My experience is my whole mangotree was underwater for 50 cm during 2-3 weeks and grew like crazy after that. They are tropical tree's, in the tropics it rains a lot in the rainingseason and they love it.

This looks like no problem at all to me but if it is winter now in CA it might be a problem, i don't have experience with mango in cold weater.

[KarenRei]

My experience is my whole mangotree was underwater for 50 cm during 2-3 weeks and grew like crazy after that. They are tropical tree's, in the tropics it rains a lot in the rainingseason and they love it.

This looks like no problem at all to me but if it is winter now in CA it might be a problem, i don't have experience with mango in cold weater.

And I once lost a mango tree years ago to root rot (and I wasn't doing anything particularly extreme), and the net is full of mango owners complaining about the same. I wouldn't chance it.  But I have to say, even with good soil, even if the roots were in very good shape before that, that's one tough mango tree you had there! I've heard of jabos and the like dealing with protracted flooding, but 2-3 weeks underwater for a mango tree? Impressive! I'm guessing that it was a very mature tree? When they get old they can put down some massively deep taproots, the flood might not have had much of an effect so deep down.

Pretty much every guide you'll find on mango growing says the same thing about mangos and soil - for example, http://homeguides.sfgate.com/soil-mango-tree-58272.html Basically, I wouldn't chance it.

[plantlover13]

My experience is my whole mangotree was underwater for 50 cm during 2-3 weeks and grew like crazy after that. They are tropical tree's, in the tropics it rains a lot in the rainingseason and they love it.

This looks like no problem at all to me but if it is winter now in CA it might be a problem, i don't have experience with mango in cold weater.

And I once lost a mango tree years ago to root rot (and I wasn't doing anything particularly extreme), and the net is full of mango owners complaining about the same. I wouldn't chance it.  But I have to say, even with good soil, even if the roots were in very good shape before that, that's one tough mango tree you had there! I've heard of jabos and the like dealing with protracted flooding, but 2-3 weeks underwater for a mango tree? Impressive! I'm guessing that it was a very mature tree? When they get old they can put down some massively deep taproots, the flood might not have had much of an effect so deep down.

Pretty much every guide you'll find on mango growing says the same thing about mangos and soil - for example, http://homeguides.sfgate.com/soil-mango-tree-58272.html Basically, I wouldn't chance it.

I think this depends. The indian mango race definitely does NOT love lots of water, the belief is that the drier the year, the more mangoes. Indian race mangoes will suffer with too much water. I have heard, however, that the southeast asian races like water a lot more, although i have never seen those mangoes in action, the only large, fruiting mangoes i have really seen are at my relative's in india where the drier the season, the better the mangoes. SO i believe that how much your tree should be watered depends majorly on what variety it is.

[bangkok]

Well it was a grafted ndm4-green tree on unknown rootstock. It was about 3 metres tall (13 feet) and growing there 2 years.

In our street all the mango-tree's survived the flooding though. Also in the neighbouring villaparks where the water was like 1.5 metres deep for 4-5 weeks they survived it. big tree's. 

A mangofarm very close to here which was underwater for 8 weeks and 3-4 metres deep was totally dead. That guy never raised his land while everything around him is raised.

Believe it or not, even some big (4 metres) plumeriatree's survived the flooding. Most of them died but some are still alive now after 2 years. Mine survived because i cut it off and replanted it, the stem was rotting but the big ones who survived never got replanted. It seems that the red flower plumeria can survive it, they still don't look healthy though but are alive. We had loads of white plumeria's along the entrance-road but they are all dead now.

Also pomelo, pomgranate survived the flooding.

I think cold temperatures and too much water are a bigger problem for mango then hot tropical temperatures and to much water.

The manilla mango has the same leaves as a ndm i noticed, waved edges.

[RGrandall]

My friend and I debated whether these meters are accurate.
On another post, CTMIAMI stated
"The only real accurate moisture indicator is a Tensionmeter. That is what I use, after spending hundreds of dollars is others over the years."

The accuracy of a soil moisture meter really depends on what you end up getting. Although most of the cheap ones that you can find at places like home depot seem like they would work great, they mostly are conductively based, which can lead to several problems. With these cheap meters, one of the things that often happens is that they corrode quickly (because the sensor isn't insulated) and this alters the reading on the meter. The other issue that occurs is that these meters are affected by salinity (i.e. fertilizer). What essentially happens is that the more salinity in the soil, the "wetter" the meter reads, even if the soil is bone dry. Obviously this is not ideal. I too have heard that tensiometers are the best choice if you are really serious about it, but most are really expensive. Having gone through my fair share of cheap meters, I finally broke down and bought this soil moisture meter. Although it is a little more expensive, (just under $100), it is fully insulated, doesn't corrode, and isn't affected by salinity whatsoever. I have been pretty happy with it for the 3 years that I've had it. I guess what I'm saying is, with the many meters I've tried out, I have concluded that you essentially get what you pay for...

Now if you don't want to put down the money to buy another meter, there are a couple of available options. If the problem in your meter is corrosion, what you can do is rub the corrosion of the sensor with a piece of steel wool as a temporary fix. As far as the issue with salinity, I haven't yet encountered a solution to that with the cheap meters.

The other option you have is the good old fashioned, sticking a finger in the soil. If it comes out dry, add more water. If you're squemish about sticking a finger in and dirtying your hand, you can also stick a piece of bamboo or similar object in replace of your finger.

Hope this helps!