Established Conifers Dying One By One

[KK2024]

I have 8 conifers that are dying one by one. They’re in a row by a fence at the back of my garden. They’ve been there years and years, a few years ago one on the end died and subsequently the one next to it died, then the one next to that died and so on. Now 4 of them are completely dead and the ones next to them are now turning brown as well. 
My question is, if I cut them down and get the roots out and plant new ones, will they just likely die too? 
And who would I get to come and diagnose what the problem is and advise what I can or should do please? 
 

[peds]

Could be a spill seeping through the soil... any other death or destruction around the first dead tree? What's on the other side of the fence?

 

Would it be too much trouble to get a few photos of the situation? 

[rapalaman]

My initial thoughts would be - has a neighbour taken a dislike to them? Either intentionally poisoning, or maybe washing paths/patio with harsh chemicals? 
I’ve also lost a few and suspect the second reason. A toxicology report on trees/soul may help but wouldn’t be cheap.

Or maybe just too dry? 

[daltontrees]

No-one has asked what species they are! That's what I'd want to know. For example if they're Lawsons Cypress then phytophthora's probably the cause.

[Mick Dempsey]

3 hours ago, daltontrees said:

No-one has asked what species they are! That's what I'd want to know. For example if they're Lawsons Cypress then phytophthora's probably the cause.

If the OP didn’t know, then I suppose everyone was waiting for the pictures to find out.

[Peasgood]

3 hours ago, daltontrees said:

No-one has asked what species they are! That's what I'd want to know. For example if they're Lawsons Cypress then phytophthora's probably the cause.

It is typical symptoms of phytophthora and not restricted to Lawsons, it isn't typical of poisoning where they usually all get sick at once.

[KK2024]

12 hours ago, peds said:

Could be a spill seeping through the soil... any other death or destruction around the first dead tree? What's on the other side of the fence?

 

Would it be too much trouble to get a few photos of the situation? 

No there's nothing else died around the first tree, but a few years ago the conker tree at the opposite end of the conifers died. The other side of the fence is a public pathway and a main road. 

I've attached some photos

IMG_8857.HEIC IMG_8854.HEIC IMG_8855.HEIC IMG_8856.HEIC

[KK2024]

13 hours ago, rapalaman said:

My initial thoughts would be - has a neighbour taken a dislike to them? Either intentionally poisoning, or maybe washing paths/patio with harsh chemicals? 
I’ve also lost a few and suspect the second reason. A toxicology report on trees/soul may help but wouldn’t be cheap.

Or maybe just too dry? 

No it's unlikely, I'm on a main road with a dentists one side and Waitrose the other side of me. Possibly dry although other plants etc around the area are thriving, a couple of acres for instance and they would likely suffer if it was dry? 

[KK2024]

11 hours ago, daltontrees said:

No-one has asked what species they are! That's what I'd want to know. For example if they're Lawsons Cypress then phytophthora's probably the cause.

I'm afraid I don't know what they are, they were there when I bought the house in 2006  I don't know the different species of conifers....they all look the same to me 🤔

[KK2024]

Im not sure if the images I put uploaded are visible as they're HEIC files from an iPhone, so I've converted to jpeg.....