Trisetacus juniperinus maybe...

I am not exactly the expert but in our nursery we sometimes have similar damages on some plants. We found a connection of this kind of damage with combination of lack of nutrition and hard sun radiation during hot summer days...

It hasn't affected every plant, only ones that demand high quality nutrition and we haven't fertilized it on time, and only during summer... Ones that were fertilized properly haven't had any damage in same conditions, just like ones that were under sun shading net...

Gary, most juniper species are at least somewhat susceptible to phomopsis tip blight, and I'll bet that's what you're seeing. A few tips: Junipers, almost alone amongst woody plants, often do better without organic mulch, like woodchips or shredded bark. Seems the phomopsis gets a boost in plants so mulched. And while I personally hate rock mulches, at least when underlain by landscape fabric, such a mulch may be appropriate here. Second, and harder to do anything about, juniper foliage can be made more susceptible to this same pathogen if it is repeatedly made to stay wet over the night hours. Obviously, if this is happening due to rain, you can't prevent it. But should it be the case that you've done some late-day or evening overhead watering, discontinuing that could help.

It is also possible that something else is going on. There is another fungal tip blight pathogen that could be involved called Kabatina. One diagnostic tool is to note when the damage occurs-early in the growing season or later.

+oM

i beg to differ on the comment that it has anything to do with lack of nutrition ...

perhaps in a pot nursery ...

but in mother earth a juniper needs absolutely NOTHING.. and presuming its an established plant.. it doenst even need water ...

and if by radiation.. he means your plant is sunburned.. i doubt that also ... again.. on an established plant ....

crikey.. 3 types of juniper are native to NY ... and nobody waters nor feeds natives .. IN NATURE ...

last year was horrible in MI .... extreme high heat ... and drought... i watered NONE of my juniper.. and the only ones that have problems.. have tip blight .... and when i get around to it.. they will be burned.. in the flames of hell ... lol ... and can go join their brothers and sisters ... that i previously castigated to such ... lol .. OK.. i am done now.. lol..

we can offer you hundreds of options over juniper.. think about removal and replacement.. before you scar mother earth with chemicals... for a stinkin juniper.. and dont get me wrong.. there are many things that are worth the use of chemicals.. but NOT a plain old green juniper ..

and for a shiny penny.. i will tell you how i really feel about juniper ...

ken

@Ken

I didn't mean to give the final answer, and as I said - I am not an expert, I only wanted to share my experience and conclusion... And you are right, i never saw such damage on juniper, but i saw sunburns that look like that on few thujas, and that was not in a pot nursery... Well, i never found out what was the exact reason of that damage but i observed and came to that conclusion... I might very well be wrong - but i only wanted to help so no hard feelings :-)

i know jalovik.... lets NOT let any language barriers interfere ... with debate and curiosity .... i meant to present my juniper 'issues' [rational or not... lol] .. rather than make you defensive ...

i got an email from OP ... gary ... he seems to have left out.. that this IS A CONTAINER garden ... on a rooftop ... and the plants are 25 years old ...

i retract EVERYTHING i said.. on the basis of new facts not presented ...

i have no experience in rooftop gardening.. nor 25 year potted plants.... nor NY .... and i dont have a 25 year old conifer ...

but i would like to see pics of his rooftop forest.. someday ...

good luck gary ...

ken

ps: but i still hate juniper with tip blight ...l ol ...

Native conifers can and do deplete mother earth of nutrician and needs to be supplemented and not necessary with chemicals,plenty of alternatives

There is one picture of the gaerden in the gallery:
http://photos.gardenweb.com/home/galleries/2012/03/rooftop_garden_in_nyc_1.html

Several of these junipers are magnificent - either bonsai or the hollywood - which is 10 ft tall, and a classic look......hate to destroy them......