By Catlady1
United Kingdom 
Hi we have 2 korean trees one has some kind of tiny creapy crawlys on it, we have tried various insectisides including jeyes fluid with no succes, but there is new growth this year. The other one is very healthy but getting to big how do we prune it.
Regards
Ann P
17 May, 2016
Answers
Not an expert on pruning conifers, but I'd have thought pruning those would irretrievably spoil the shape. When buying a tree you need to plan for its mature size . You can't normally keep a naturally tall wide tree small by pruning it.
17 May, 2016
Agree Stera... and these want to be big trees!
17 May, 2016
Re. pests - the RHS says that Abies koreana (Korean fir) can get aphids and adelgids.
We found the best answer to bad aphid infestations of our conifers (Picea pungens Hoopsi and Picea pungens Koster - which also had close needle arrangements, making treatment difficult) - was "Provado Ultimate Bug Killer".
It is a Contact and a Systemic treatment. So a generally good spray also treats all the areas you miss inbetween the needles.
The aphids start doing damage when they are really tiny and by the time they are easily visible - the needles are damaged/grey.
Re. pruning - see this site: http://www.finegardening.com/how-prune-conifers
Go to Page 2 and then scroll down to "STIFF NEEDLES" and "Firs" advice.
Examples of some previously pruned conifers are here (although Fir is not included):
http://fourseasonsgarden.co.uk/www.fourseasonsgarden.co.uk/Pruning_conifers.html
17 May, 2016
Hi Catlady and welcome to GoY. Can you get a close up photo of the creepy crawlies? This looks more like dieback than an infestation to me.
17 May, 2016