Leylandi turning brown???

Hello
My 5 years old leylandi hedge has started to go brown in 1 area and is spreading. It’s in the middle of a stretch of 100 trees, it’s going brown from the middle. The top section hasn’t grown as well as it neighbours last year. This year I noticed brown patches on the tree that has poor top growth and now it’s spreading to nearby branches. I’ve attached photos. I couldn’t see any bugs/insects on it. Does anyone have any ideas how I can fix this issue?
Thanks!

 

As far as I know this is due to dryness but could be due to an aphid damage. The brown parts will not regrow.
Others on the forum will have better knowledge.

 

The usual reason is a lack of water as said above.
But why just one out of 100 is suffering seems unusual.
I doubt aphids have anything to do with it.

Due to their waxy leaves,they lose water very slowly so sometimes by the time the inside starts to go brown (i.e. die), the whole tree is already dead.
That may or may not be the case with yours - I can only suggest plenty of water - like 3-4 bucketfuls once a week (unless you get heavy rain) and see if it gets better or worse. One of mine has more brown inside than I would expect, but it's still alive and growing.
If it has died, the space will likely be filled by those on either side.
But it may just be some dieback of certain branches, so water, wait and watch.. and maybe keep your fingers X'ed

 

Just a really nasty idea here - could it be a neighbour’s way of saying they don’t like the prospect of a huge hedge at the end of their garden, maybe cutting out the light and making their garden dry and infertile?

 

try to convince yourself its orange rather than brown, like autumn leaves

leylandi does that.

 

That looks like a very small hedge for 5 years old @Katie.mac . If it hasn't had adequate prep and water right from the start, it'll have struggled. Properly established leyland hedging will grow rapidly after a year or so -gaining as much as 2 to 3 feet per year if conditions are good. It's why they also need regular trimming from early on, and why so many of them get out of control.

I'd cut out any brown branches/stems and then clear about a foot's width of grass/turf from the base, to make a better/wider border, and refresh all the soil, watering really thoroughly. The most likely reason for browning/not thriving is lack of water, as mentioned earlier on, but the damage may already be done, as also mentioned. Conifers are shallow rooted, and can carry on a long time before damage is clear, and by then it's too late. Very few will regrow from brown wood, and leylandii are in that category.
The other main reason for bits of browning branches is wildlife. Pigeons love trying to nest in all sorts of conifers, and they're not particularly careful about how they land. If it's just a small are, it wouldn't matter too much long term.

 

What is on the other side of the hedge as it looks a bit bushy on this side so I was wondering what the other side looked like? Maybe the neighbours on the other side of the hedge has been at it. I for one would stop a neighbours leylandi hedge from growing if they tried to plant one. A friend kept snipping the tips off when his neighbour planted one.