Ficus benjamina mystery

[namer90]

Hello everyone one
Am new to this forum and I wish someone could help me to find out whats going on with a tree i got
First : its a garden wall ficus benjamina
The wall seems fine except one tree suddenly dry and fall with colored leafs
I asked lots of experts but seems that everyone give me a different answer
Second : an watering 2 times a week with auto drop system this tree isbthe only one which get thia symptoms
I will upload the photo and wish i get an advice

 

[YumYum]

Well sometimes you can get different answers and they all be right. The purplish leaves look to have a phosphorus deficiency as you can compare to this picture. That is one answer.

If it does then why would it have a phosphorus deficiency? The pH could be way off. When the pH is out of bounds plants cant pull up certain nutrients. That is answer two. The soil could be just lacking phosphorus. Sand wont hold nutrients the same as a clay soil. That is answer three.

I see some very very dark green leaves on the top of the left tree and very green leaves in the interior of the other trees, so you must have been fertilizing with something.

 

[cpp gardener]

Check the trunk from bottom to top for some kind of injury, especially at ground level.
Make sure the soil level is the same as the original level.
How long has it been planted there?
Soil chemistry is unlikely to affect one plant in the middle of a row without any signs on the neighboring plants. Check the emitters closest to the failing tree. They might be plugged.
Post some pictures of the base of the tree.

 

[namer90]

Well sometimes you can get different answers and they all be right. The purplish leaves look to have a phosphorus deficiency as you can compare to this picture. That is one answer.

If it does then why would it have a phosphorus deficiency? The pH could be way off. When the pH is out of bounds plants cant pull up certain nutrients. That is answer two. The soil could be just lacking phosphorus. Sand wont hold nutrients the same as a clay soil. That is answer three.

I see some very very dark green leaves on the top of the left tree and very green leaves in the interior of the other trees, so you must have been fertilizing with something.

Thank you

 

[namer90]

Check the trunk from bottom to top for some kind of injury, especially at ground level.
Make sure the soil level is the same as the original level.
How long has it been planted there?
Soil chemistry is unlikely to affect one plant in the middle of a row without any signs on the neighboring plants. Check the emitters closest to the failing tree. They might be plugged.
Post some pictures of the base of the tree.

I will make a full some photos. And post it here
Thank a lot

 

[DirtMechanic]

Closer clear pics of both sides of leave and of stems and bark are helpful.

https://scialert.net/fulltextmobile/?doi=pjbs.2014.364.371

Botryosphaeriaceae seem problematic there. Generally a systemic fungicide could be of use if that is what is identified.