We have a foliage disease of trembling aspen (Populus tremuloides) in
southwestern Colorado, USA.  It is beautiful, strikingly unique, appears to
be causing significant impact, and has me completely baffled.  The
foresters who brought it to my attention are calling it "tiger blight"
because of the distinctive striping (see pictures below).  It is occurring
mostly on suckers and saplings and lower branches of overstory trees.  I
was told that in one regenerating stand of suckers, it is killing 30-40% of
the foliage.

There is no fruiting (perhaps very early initials), but there are hyaline
hyphae in the lesions.

If the striping is caused by alternation between night and day (and I can't
think what else would lead to the zonation), the lesions appear to expand
rapidly.

I put some leaves in a moist chamber to see if anything fruits.  In the
meantime, has anyone seen this disease before, or even similar symptoms on
another species?

(See attached file: tiger_4.jpg)
(See attached file: tiger_5.jpg)
(See attached file: tiger_group_1.jpg)

Thanking you in advance,

Jim Worrall

US Forest Service
Rocky Mountain Region
Forest Health Management
216 N. Colorado St.
Gunnison CO,  81230

(970) 642-1166  desk
(970) 209-1332  cell
(970) 642-1919  fax
-------------- next part --------------
A non-text attachment was scrubbed...
Name: tiger_4.jpg
Type: image/jpeg
Size: 93951 bytes
Desc: not available
Url : http://lists.iufro.org/pipermail/rg70200-forpath/attachments/20080710/5458cb2e/attachment-0003.jpg 
-------------- next part --------------
A non-text attachment was scrubbed...
Name: tiger_5.jpg
Type: image/jpeg
Size: 113858 bytes
Desc: not available
Url : http://lists.iufro.org/pipermail/rg70200-forpath/attachments/20080710/5458cb2e/attachment-0004.jpg 
-------------- next part --------------
A non-text attachment was scrubbed...
Name: tiger_group_1.jpg
Type: image/jpeg
Size: 122513 bytes
Desc: not available
Url : http://lists.iufro.org/pipermail/rg70200-forpath/attachments/20080710/5458cb2e/attachment-0005.jpg