I run a pathology diagnostic lab at the Great Lakes Forestry Centre in Sault Ste. Marie, Ontario and sure enough, I just got a sample of C. whetzelii in and the symptoms are exactly the same.  I don't remember noticing before.  Guess I pay most attention to the sclerotia.  Learn something new every day 

Chuck Davis

-----Original Message-----
From: rg70200-forpath-bounces at lists.iufro.org [mailto:rg70200-forpath-bounces at lists.iufro.org] On Behalf Of James Worrall
Sent: Monday, July 14, 2008 10:35 AM
To: rg70200-forpath at lists.iufro.org
Subject: [IUFRO RG 7.02 FORPATH] "tiger blight" -- -- = ink spot?



Many thanks to those of you who wrote back about the distinctively striped foliage disease of aspen.

Mike Schomaker (also in Colorado) said that he has seen this as an early stage of ink spot, caused by Ciborinia whetzelii.  He was initially puzzled until he saw sclerotia forming in the symptomatic leaves later in the season.  I rechecked a few descriptions of the disease, and an initial zonate pattern is mentioned briefly but I have not found a photograph of it.

After incubating my "tiger blight" for 3-4 days, the zonation is beginning to fade and sclerotia have begun to form (see photo below).  So, it looks like Mike is correct (congratulations, although I was starting to like the name tiger blight!).  I will follow the development in nature through the summer and see whether it begins to look more like ink spot as usually pictured.

Thomas Kirisits wrote about Septotinia podophyllina and referred me to Butin.  Luckily I have his books.  In Forstpathologie für Studium und Praxis (1973), he describes and presents a drawing of Ringfleckenkrankheit der Pappel, caused by Sclerotinia (Septotinia) podophyllina.  It makes somewhat round lesions with concentric banding.  It has an asexual stage (unlike Ciborinia)  with large conidia and produces apothecia in the spring.  In Krankheiten der Wald- und Parkbäume (1983), he refers to the pathogen as Septotinia populiperda.  This fungus is closely related to Ciborinia (both in Sclerotiniaceae) so it is not surprising it might produce similar symptoms.

Risto Jalkanen referred to a similar disease of unknown etiology he has seen on Salix caprea.  Perhaps it is caused by a related fungus.

Several people suggested the possibility of leaf miner (insect) damage.  It certainly is reminiscent of leaf miner damage (which we actually saw at the same site), but we (including entomologist Tom Eager) are convinced that it is not leaf miner.

Thanks again to all who kindly wrote back with assistance or just excitement!


(See attached file: tiger_incubated_spots_2.jpg)

Jim Worrall

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

(970) 642-1166  desk
(970) 390-2352  cell
(970) 642-1919  fax