Is this sooty mold on my tangerine tree?

[lane711]

Hi, I've had this tangerine tree growing in my back yard for several years.

It generally only produces fruit on one or two branches for some reason despite it being over 10ft tall. I recently had it trimmed, but before that is was hitting into the trees next to it.

There is also some type of mold growing on it. Is this sooty mold or something else?

 

[Tetters]

Hello @lane711 Welcome to the forums. That certainly looks very much like sooty mould, and it has probably been introduced by some kind of insect which has been sucking the sap out of it.
As well as getting rid of the mould, I think you need to try and look for the culprits that caused it. If it is aphids, it will be easier to deal with, but you need to check carefully for things like mealy bugs or scale insects to find the correct solution for the problem.

 

[redback]

Can you prune it now? I got rid of a much worse case on my orange tree by letting the air flow and wind blow it away.

 

[lane711]

Thank you. Yes I will just prunte the moldy leaves since its not a lot. Could this cause the tree only producing fruit on 1 or 2 branches or is that likely a different issue?

 

[redback]

First check if you get heavy frost or snow and ice in the coming months that would prohibit a heavy pruning.
If you have a maritime influence and are free of frosts, you can prune the tree hard. Remove all cross over branches, all dead and diseased wood and leaves and any branches growing inward towards the trunk. It looks a bit like my orange tree in the photo.
Otherwise a light pruning might help.

 

[lane711]

First check if you get heavy frost or snow and ice in the coming months that would prohibit a heavy pruning.
If you have a maritime influence and are free of frosts, you can prune the tree hard. Remove all cross over branches, all dead and diseased wood and leaves and any branches growing inward towards the trunk. It looks a bit like my orange tree in the photo.
Otherwise a light pruning might help.

Thanks, will do that. I'm in southern California so no risk of cold. I have a lemon tree on the other side of my tree that has been highly productive, so I'm still confused on why this tree has not been, especially when its grow so high and appears healthy aside from the mold on less that 10% of the leaves.

 

[redback]

The color of those leaves does indicate some nutritional deficiency. After pruning look to add iron and magnesium to the soil and raise the pH. There will be specific citrus fertilizers for these corrections. I'm an organic advocate so I would recommend - a bag of poultry manure and a light sprinkling of wood ash to the soil inside the dripline with some iron chelates either as a top dressing to the soil or a foliar spray. I would also spray the leaves with a diluted seaweed solution.

 

[redback]

Also, water in some Epsom salts well when you give the root zone a good watering.