Canadian Hemlocks tend to carry a disease known as the woolly adelgid. This may have something to do with their decreased production.

-Sam

Gee's and Greer still have them as does Rich's Foxwillow Pines. Locally, here at least, they have them as well.

..."disease known as the woolly adelgid..."

Well, insect pest, actually, and that's limited mainly to the norhteast US.

tj

That pest is moving rapidly from what I've read. It has completely infected my hemlock and I'm further south and east than the native hemlock population. I don't think Maryland is considered a Northeastern state either (mid-Atlantic or southern state).

Another T.J.

Well, ok, northeast is a relative term. See the link.

tj

Here is a link that might be useful: HWA Spread

We've had adelgids on western hemlock in this region for years.

They were on Hemlocks in Northern Virginia in the mid 1990s. I think the fact that map doesn't indicate infestation in much of the SE US is because they simply don't grow there, not because they haven't spread to those areas. They are mainly cultivated in the NE USA.

Karate626 what are you doing to save your hemlock?

Some states have enacted quarantines restricting the import of Hemlocks. Here in Ohio that is in effect and Hemlock can't be shipped in from the East Coast.

Last month I toured a garden that had a mature Japanese Hemlock. (Tsuga Diversifolia) It was a very attractive tree with a bi-color effect due to the silver underside of the needle. There has been speculation that strains other than Canadensis or Carolina may be resistant to the Wooley Adelgid. If anyone has seen additional data about that please post it. Perhaps the best course of action is to propagate from this plant next winter and send plants to as many locations around the country as possible to get a good sampling of resistance.

Hemlock Woolly Adelgid (HWA) was first recorded in the PNW in the 1920s; Western Hemlock is only moderately susceptible, so losses haven't occurred on anything like the extent that they have on Eastern Hemlock with the more recent (1950s) appearance of HWA on the east coast.

The Asian species of Tsuga are all resistant to HWA, having evolved alongside it. That includes T. diversifolia, T. sieboldii, T. chinensis, T. forrestii, and T. dumosa.

Resin

Thanks Resin. Are there any of the Asian Hemlock that you find appealing?

I just cut down and dug out my 30 year old or so Canadian Hemlock. It became tough to prune to 8 ft height and width. It was healthy, and my county in upstate NY was not to have those HWA insects anyway. It got replaced with Picea omorika 'Pendula Bruns', is much nicer!
Bernd