[solved] Lumps growing on branches - disease or insects?

[Peep]

[EDIT] Solved ->The conclusion is copper deficiency: https://www.researchgate.net/figure/Symptoms-of-copper-deficiency-in-nurseries-trees-A-with-formation-of-gum-pockets-in-new_fig1_319653198

Hello

I have this Keraji with weird lumps / bulges on the branches. This plant had the same issue last year on one new branch (I think), the last one of the season, which I cut off.

However it's present again this year. It could be gall wasp, but to me it doesn't completely fit the pictures, but maybe I'm wrong. If it was insects I would have expected that it would have been removed last year when I cut the branch off. Or that I would have found the same problem on other plants. But only this one, out of over 50 citrus plants, has shown this problem, two years in a row...

The lumps are partly filled with what looks like resin.

First two pics are from last year













cut open:






Anyone here that can tell me what causes these lumps? Fixable, or do I need to burn it and find a new Keraji?
The color of the leaf stems is also maybe a bit weird because it's not uniform.

[Peep]

@Millet  could you be so kind to move this to the general citrus board, that's where I had intended to post it 

[poncirsguy]

citrus gull wasp?

[shot]

copper deficiency?

[Peep]

Little update.

- A fair bit of resin blobs have kept coming out if it, In random places and also where a branch was freshly cut off.

- I cut down most of the plant, usually insects prefer the younger growth so I hope the stump that's left is 'clean' and I'm keeping an eye on it.



- I found this insect on another plant, it looks similar to gall wasp, but also like an ant: https://commons.wikimedia.org/wiki/File:Lasius_claviger_male.jpg



Any bug experts here?

Also, I wonder, will only the citrus gall wasp infect citrus, or are there others from the hundreds of different species of gall wasps that will also infect citrus? I'm in Belgium, Europe, and it seems that citrus gall wasp is mainly a problem in Australia.

copper deficiency?

Last year someone also mentioned this, but unless Keraji needs way more copper than other citrus cultivars I don't see how only this plant would have this repeated issue. A few weeks ago I gave it some copper sulfate anyway, but this was after the symptoms were already there, so currently I have no idea if it has any effect.

[Peep]

copper deficiency?

This picture (and paper) seems to match my plant well enough that I'm now sure it's copper deficiency!

https://www.researchgate.net/figure/Symptoms-of-copper-deficiency-in-nurseries-trees-A-with-formation-of-gum-pockets-in-new_fig1_319653198

I'm surprised a bit, because the plant had just as much nutrients as all the others, but it seems I need to figure out what has gone wrong in the feeding or soil of this plant for two years in a row. In spring I even repotted it with new and different soil than last year so it's a bit intriguing that the issue persisted.

[tru]

copper is available at only very low pH reading (7.5-7 and below technically but it really starts ramping up past 6.5), maybe some pH down will fix the problem for good

https://www.rhomarwater.com/pdf/Copper%20Solubility%20with%20pH.PDF
https://accelconf.web.cern.ch/p01/papers/tpah106.pdf (page 2)