Can there be a problem if close to each other?
If you give them both plenty of space, it shouldn't be a problem. At least 6 feet if not more. Issues arise if their canopies and roots intertwine. However, it never hurts to contact your local extension service and run this question by them.
https://www.gardeningknowhow.com/extension-search?zip=93257&radius=50&services_search_action=search&submit=Search
Hi- my miniature mandarin orange doesn’t produce fruit. The underside of many leaves has a disgusting looking white and black substance clinging to it. Almost looks like white crystals. Is this Leaf Miner? Please tell me I can blast it with something without destroying the pest’s natural enemies!
It doesn't sound like leaf miners but it could be mealy bugs or scale. The black is sooty mold. Here is more:
https://www.gardeningknowhow.com/edible/fruits/tangerine/mandarin-orange-tree-care.htm
https://www.gardeningknowhow.com/edible/fruits/oranges/no-fruit-on-orange-trees.htm
https://ucanr.edu/blogs/blogcore/postdetail.cfm?postnum=29424
https://www.gardeningknowhow.com/plant-problems/disease/how-to-get-rid-of-sooty-mold.htm
So I got a murcott semi-dwarf mandarin tree and from root to tip its 2 ft tall. It gives fruit but the tree itself hasnt grown since I bought it. Any idea why this could be?Are they REALLY SlOW growers?
They can be, and being a Mandarin- It is short-statured to begin with. If it is producing, edible, fruit then it should be considered healthy! Unfortunately, your photos did not come through. I am unable to see the state of the tree.
For the best growth, offer the tree the best care. This article will help:
https://www.gardeningknowhow.com/edible/fruits/tangerine/mandarin-orange-tree-care.htm
Fruit starts to get yellow and then brown spots appear in the yellow spots. then the whole fruit go brown.
This sounds like Phytopthora infection, unfortunately. This will be something that will be managed, rather than cured. Here is an article that will help you to do so:
https://www.gardeningknowhow.com/edible/fruits/citrus/citrus-fruit-brown-rot.htm
It has not even produced flowers.Plenty of Bees around
If it was fruiting prior to these two years, then I would suspect that the soil has run out of nutrients. You can test for deficiencies, then feed with a citrus fertilizer.
https://www.gardeningknowhow.com/garden-how-to/soil-fertilizers/testing-soil.htm
https://www.gardeningknowhow.com/garden-how-to/soil-fertilizers/soil-ph-plants.htm
Question 1: I transplanted a dwarf mandarin tree in the ground in November of 2019 and it has now grown to 130cm high. Last year and the year before, when the tree beared fruits, I pinched all the young fruits off to let it establish. I wonder if I still need to do so this year or I should retain some of the fruits. If so, how many fruits should be left on the tree? Will it affect its growth for a tree only two years old in the ground? Question 2: There arw 6 main branches on the three, of which three branches look thich, whereas other three are thin. I would like to know if I need to trim the three thin branches off, and if I leave them to continue growing, are they beneficial to the tree or they are useless at all. Thank you very much in advance for your kind consideration and time.
You can go ahead and let it fruit if you would like. I would only prune if branches are touching or crossing, though. Otherwise, it isn't completely necessary at this time. Here is an article that will help you with the care of the tree:
https://www.gardeningknowhow.com/edible/fruits/tangerine/mandarin-orange-tree-care.htm
The original stalk seems to be dead but a whole other stalk has grown out and there is nothing but thorns...I've read that I might need to start over with another tree. I've also read that in 3-6 years again it might flower. What is my best option from this point.
The new stalk probably grew from the rootstalk if the tree was grafted (which it likely was unless you grew it from seed). Those are not usually desirable, and take years to fruit, if they fruit at all. I would recommend starting over with a new tree.
https://www.gardeningknowhow.com/edible/fruits/tangerine/mandarin-orange-tree-care.htm