What killed these?

[2BuckBizCT]

I have a line of these trees behind my pool. Maybe 2 months ago I noticed one was dropping green on the mulch. It appears to have spread to a second one. I cut the first one down and will dig out the stump. But curious as to what people think happened? Bugs, disease? Hoping I can find a replacement to plant that is similar in size. They are like 7-8 feet high. 

[mowin]

Some sort of needle drop disease perhaps. 

[2BuckBizCT]

4 minutes ago, mowin said:

Some sort of needle drop disease perhaps. 

Should I cut down the others or just trim the dead stuff off?

[mowin]

4 minutes ago, 2BuckBizCT said:

Should I cut down the others or just trim the dead stuff off?

Hard to know.  Could be some fungus or root rot. It clean up as much as you can from dead trees to minimize the spread if it is fungal.  Removing the roots might help also. 

Do you know what type of evergreen?  

Most evergreen will "shed" needles every fall to few yrs. Needless don't live forever.  But it the tree looses more than a third of it's needles, it's mostly likely not going to survive. 

[2BuckBizCT]

3 minutes ago, mowin said:

Hard to know.  Could be some fungus or root rot. It clean up as much as you can from dead trees to minimize the spread if it is fungal.  Removing the roots might help also. 

Do you know what type of evergreen?  

Most evergreen will "shed" needles every fall to few yrs. Needless don't live forever.  But it the tree looses more than a third of it's needles, it's mostly likely not going to survive. 

Not sure what kind. I have about 50 of them behind the pool. Been here 2 years. And this is the first one to lose needles and completely go brown. It appears whatever the one I ripped out had, has spread to the next two as well. 

[mowin]

1 minute ago, 2BuckBizCT said:

Not sure what kind. I have about 50 of them behind the pool. Been here 2 years. And this is the first one to lose needles and completely go brown. It appears whatever the one I ripped out had, has spread to the next two as well. 

If it's fungal, it will continue to spread. Might be time to call in a expert in your area. 

I've heard mold in mulch might be the cause, but I can't confirm.