My starter Chinese Elm seems to have some sort of rot/fungus. Should I be worried? Any help will be much appreciated!

I am glad you state your tree a starter but when you say fungus what do you mean. The green stuff on the soil is moss and the white stuff is slt deposits from use of hard water. I would advise to repot it next spring into more structured soil like akadama or anything similar. For now if you want to keep it alive you may need to place the tree outside under some shelter for winter but move it out side slowly/aclimatize it. Try to use a less hard water like rain water or something. I may be wrong so wait for further posts

Looks more like a mould than chalk deposits. Use a soft toothbrush and rub it off, check to see that there are no bugs in it as it could possibly be mealy bug. It is difficult to see from the pictures. Depending on what country you are in will dictate where you keep it. You need to learn how to water and look after this plant before you do anything else to it.
When you water put the pot into a bowl of water and wait for the bubbles to stop thn allow to drain. Wait until it is almost dry and water again the same way. Check every day with a chopstick, if it comes out clean then it is time to water.

All bonsai start somewhere If everyone were masters we may not be posting here at all... There have been some small black fly on a few of my indoor plants but it's a little late in the year for them, I wondered whether this was linked... Re: putting it outside, Would a mobile greenhouse do the job, I have a couple outside already that look somewhat like a travel clothes rail? I was under the impression frost kills Chinese Elm? I'm in UK and it is predicted to have the coldest winter on record this year.

EDIT - re second comment, thanks, I'll take a toothbrush to it today. I used to water from the top with a fine watering can until it comes out of the bottom and started watering like you said recently. However I went away on holiday and had to leave it in water for over a week. I have also started lightly spraying my indoor plants a few times a day to counter the dry atmosphere, shall I stop spraying this one?

drummerboy wrote:

However I went away on holiday and had to leave it in water for over a week.

You mean you've kept it standing in that plastic container filled with water? Not good.
Trees belong outside, so does the chinese elm, but it can be kept indoors. If it is used to being inside, do not put it outside this winter. The soil looks quite bad. Using a toothbrush won't help, better repot the tree and clean the pot. If this tree has been inside, repot it now. Remove the soil, try not to disturb the roots, plant it in fresh new soil.

When did you wire the tree? What material did you use to wire, and why did you wire it?

drummerboy wrote:

All bonsai start somewhere If everyone were masters we may not be posting here at all... I have also started lightly spraying my indoor plants a few times a day to counter the dry atmosphere, shall I stop spraying this one?

I have to say that i agree with that statement. But i would stop spraying as it does not help at all. You see it only benifits for about fifteen minutes so you would have to do it like fifty times a day to create ideal humidity. Definitely repot as auk said into a soil more suited to trees in pots tip:dont get "bonsai soil" (commercialized peatt and other rubbish called bonsai soil). Where in the uk are you as i am in london and many nurseries are available here. It will be a cold winter, any tree which is in a pot can be killed by frost. Maybe wrap the pot in bubble wrap for insulation if really worried and place in a sheltered position. I think you can repot now but that question should be asked to other than myself.

The stuff o the roots and soil is calcium with some iron-based minerals on them. Seems like a lot of salts have accumulated, partially due to leaving it standing in water I presume. Def. repot soonish. It is also causing your plant to look sickly.

By the way: People who now know whether the winter will be warm or cold should get a job as fortune teller. Just always work on the assumption it may be cold, but treat the tree fitting to the weather fo that moment.

You mean you've kept it standing in that plastic container filled with water?

Yes for a over a week. In general, I stick to the rule of watering and leaving a little in the bottom to create humidity but it doesn't go anywhere near high enough to reach the drainage hole.

better repot the tree and clean the pot. If this tree has been inside, repot it now.

I was given it as a present earlier this year from the Japanese Gardens, Cornwall. I bought the generally used tesco cat litter (aka cheap akadama), peat compost and perlite to use on my various other plants that I can use for the new mixture.I haven't re potted before so will be a new experience!

When did you wire the tree? What material did you use to wire, and why did you wire it?

Wired it last week, I've used plastic coated garden wire as a kind of test wiring (first time). Have ordered some aluminium bonsai wire for future wiring. Did the wiring as the tree was full of branches crossing each other and weak branches mixed in. It shed it's leaves earlier in the year before it was passed onto me so I nursed it back to health and thought now was a better time to give it a tidy up. It's only now that I am noticing the rot and such so it's very recent.

People who now know whether the winter will be warm or cold should get a job as fortune teller.

Haha I know right... I hope they're wrong!

Thanks for all the help guys, apologies my questions may be rudimentary but hey we all start somewhere!

bob wrote:

Definitely repot as auk said
I think you can repot now

bob wrote:

I would advise to repot it next spring

Still claiming you don't twist your answers, Bob?

bob wrote:

I think you can repot now but that question should be asked to other than myself.

i have learnt, not twisted. but i guess i should have added that within my post