Newbie poster? Am gonna link you to my post about MPT from several years ago.

Two very harsh vortex winters in a row. Sometimes plants dont always die right away. But they get weakened. Especially marginals. The late spring frosts this year were very hard on some plants too. Of course it could have been another issue ss well.

There is duration of cold and the absolute low. The two previous winters had duration of cold in spades but last winter, though generally mild, had a severe arctic breakout that saw the coldest temperatures in ~10 years around here. Could it have been a similar situation in your area?

Yes, I meant to attach this photo. Columbia, MD is probably zone 7a. As Dave says, we've had two harsh vortex winters in a row, while last December was unusually warm. While trying to find some exact figures on temperatures, I noticed that we did hit 80 in March and then had a cold spell in April in the low 20s.

I actually don't think it had anything to do with the polar vortex winters; or their effect was minimal. I saw the almost 50 foot Bethesda tree after the 2nd winter and it looked just fine. Cevi is not reporting that it had extensive, visible damage after the polar winters and I doubt it did.

" In fact, last year's rain was well over the average for this area, but without any flooding in this garden."

This is the far more likely explanation. We had one of the wettest early summer periods we'd had in years. Allowed Phytophthora root rot sp. to really go wild. In late June/early July I lost a grafted magnolia that was in a slightly poorly drained spot. A few rare Asian cloudforest/alpine perennials died. etc. etc. Araucaria araucana comes from a climate with crisp, cool, dry summers...nights in the mid 40s, if not cooler(!)...and is almost always going to be prone to sudden failure in a climate with hot, wet summers. The 4 or so known large trees in the mid-Atlantic are rare exceptions if you consider how many hundreds or even thousands have been sold by high end nurseries over the past 40 years. There should be one in every upscale neighborhood, there most definitely is not. Funny enough I am aware of another tree in Columbia, near one of the lakes, that was about 8-9' when I moved from there in 2006, but died 2 or 3 years later. They usually die 2 to 5 years after planting, consider yourself lucky that you got more. If you look at how different the climate is where they originate, it's kind of amazing they last _that_ long around DC.

There has been some noticeable recent mortality in the much more suitable general conditions here, and there is also a disease problem threatening wild stands.

Thanks, I hadn't known that.

Thanks to all of you for the wealth of information and experience you've provided. I guess I'll take davidrt28's advice to consider myself lucky that the tree lasted for 13 years through all sorts of weather variations.

Yeah, 13 years was a very good run around here.

I wonder if the existing East Coast trees might have some genetic variance that would help them resist whatever is now injuring some of them in the PNW; on the other hand of course the native population will contain the greatest genetic diversity so hopefully plenty of them will be able to survive whatever the pathogen is. To "solve" potato blight - another phytophthora species of course - plant geneticists had to go back to the original native habitat of the potato to "find" a large enough gene pool to search for resistant plants. They have a faster generation time...to be sure!

Also wonder though if this is somewhat like the case of the native Arbutus in the PNW that do poorly in irrigated, fertilized gardens. When I saw monkey puzzles on my first trip to the west coast they often seemed to be in unattended areas...perhaps because in "well maintained" home gardens, people got tired of them when they were no longer "cute"!