If I assume that you are just looking for conifers that will do well in zone 6 (not looking to grow from seed) then the first thing I would do is check out Conifer Kingdom. There you will have the ability to search by hardiness zone, and if you decide to buy, they sell good plants. https://www.coniferkingdom.com/zone-6/

I am asking about health issues related to Picea pungens not the zone hardiness. They seem to suffer from needle cast and Cytospora canker in warmer areas. I am wondering if all Picea species are prone to these problems or is pungens more susceptible.

Sorry, I guess I misunderstood... There are people around here who are much better equipped to answer that. But, I am sitting here at my computer, so I looked a little into it. It seems that Picea abies (Norway Spruce) is also susceptible (this according to CT, here: https://portal.ct.gov/CAES/Plant-Pest-Handbook/pphS/Spruce-Picea) and that Picea omorika is considered to be a good spruce in warmer climates (ran across it several times, but here is the Missouri Botanical listing: www.missouribotanicalgarden.org/PlantFinder/PlantFinderDetails.aspx?kempercode=h220). Probably somebody will come along from ACS or someplace and give you more info!

climate zone alone is not enough ,,, location is req.

ron

fairfield county Connecticut. 1 hr from nyc.

pungens , yes very susceptible

other picea , not so much

I have lots of norways in Ill. , only small amounts of needle cast on some plants

also on Picea glauca...small amounts

so stay clear of pungens ,,plant away for others

ron

I’d suggest finding local, private growers/nurseries in your area, and contact them. They have an intimate knowledge about what works, and will be able to provide you with all of the answers you could want to know.

but local growers are still selling the dreaded Picea pungens

ron

I'm so glad that someone else already started a discussion on this very topic. Yeah, I forget if it was "The Spruce" or some other publication, but basically the average life expectancy for Picea pungens in the landscape of warmer, lower elevation climates is around 60 years - only a fraction of its max lifespan in the wild. Picea omorika or Picea meyeri are probably your best bets. Fast-growing-trees.com and thetreecenter.com should have them.

"I’d suggest finding local, private growers/nurseries in your area, and contact them."

The problem is, in the final analysis, there are still plenty of such growers out there promoting crap plants. I've seen blue spruces at more than a couple 'high end' nurseries in the I-95 corridor between NY and DC.