Need help with Fargesia rufa bamboo

I've never had bamboo plants but I've gone and bought 3 pots of fargesia rufa plants online but they don't look healthy as the stems are yellow and there's a lot of white on the stems and I found some orange/brown bugs. So my plan is to repot them from the 9cm pots but what compost should I use and what size pot and how much water should I give them and should I add fertilizer. If the white on the stems is from bugs will spraying them with soapy water get rid of them.

 

I'd put them into 25cm pots with a John Innes 3 compost. Over summer I would water when the top couple of inches of compost feels dry and feed once a month.
Pictures of bugs would help possibly scale insect though. The white might be from the bamboo as some have a white powder on the stems that gradually comes away .

 

Before I washed the white from the stem/new shots it looked liked a white webbed powder. I've had a look on google and the bug looks like a Palmicultor lumpurensis. I have john innes 3 but I only have a 17cm pot so when I repot do I need to put gravel in the bottom of the pot and should I remove all the old soil from the roots. When I feed it what would you recommend as I have bonemeal,growmore, blood fish & bone.

 

Where abouts are you? Is Palmicultor lumpurensis actually found in the UK? I see it is a pest in Florida and Asia and has been found in Padua, but I couldn't see a reference for occurrence in the UK. You could email the Natural History Museum and ask them.
I was thinking of feeding with Miraclegro or Phostrogen once a month as a liquid feed.
You could mix some blood fish and bone in with the JI3 and then top dress yearly, I don't think you need to put gravel in the base. If you cannot see bugs on the roots then I wouldn't remove the old soil.
Interesting that the bug is on the fence and not the bamboo, wonder what it's up to. If a tropical pest it might not like our climate.

 

Do you think the bug is a Palmicultor lumpurensis? I'm from wales. I ordered the plant from a nursery in england. I took the bug off the bamboo and put it on the fence to take a photo.

 

I would be surprised if it was Palmicultor lumpurensis, but I'm no expert on insects. You could try getting the largest clearest picture you can and posting it here https://www.ispotnature.org/add/observation or contact Local Entomology group, the Natural History Museum or you could try The National Botanic Garden Of Wales.
How many of them are there and are they increasing?

 

Fair bit of info on the net. Just search. Palmicultor lumpurensis

 

Pretty much what you've described is a mealy bug Balanococcus kwoni, or it could be an armoured bamboo scale insect, which latin name escapes me. Try spraying with a soapy washing up liquid twice a week until you've got rid of them and feed monthly up until September with a weak nitrogen feed.
I do put my grass cuttings around the bottom of a few of my fargesias, as a nitrogen boost

 

Search under @flounder s name for the bug throws up
Pests with a good picture of it.

 

I've had a look at the pictures and it looks more like a
armoured bamboo scale Insect, Kuwanaspis pseudoleucaspis. I asked the place where I bought the plant and they said if it's a palmicultor lumpurensis use a systemic pesticide. I cannot see anymore but when I get up in the morning the leaves have white marks on and today it looked like a cobweb coming out the soil.