I have a japanese black pine which is about 5-6 months old now. Two days ago I noticed that one needle has turned yellow and some other needles at the lower part of the plant looks to me that they have yellow tips. The top part looks ok to me.
I leave in London, UK and weather has started getting a big colder now (around 5C at night reaching 13C midday). I took the plant indoors since I noticed the yellow needles in case it has to do with the cold nights.
How the plant looks to you please, is this the starting stage of a disease? I have two other black pines of the same age on separate pots and these look ok to me. It is only this one that looks alarming to me.

Many thanks

It looks ok to me.

gmiliotis wrote:

I took the plant indoors

Don't do that unless when you want to kill it.

Move it back outside. Inside is a sure fire way to loosing pines.

Older needles die off. It is normal. If you see a general yellowing keep it more sheltered from rain. You want the plant to stay dryish through winter.

Thanks everyone for your helpful input. It is reassuring you dont see anything too bad on the plant. I am a total beginner on bonzais, these are my very first trees