Thanks Bill, for your helpful link to Poinsettia care.
I believe that in funnyfarmresident's tip about Poinsettia disease, she was referring to "Botrytis". What I found on the subject is from Dr. Larry Barnes, Professor of Plant Pathology/Extension Specialist - Texas A&M University System. (I didn't search any farther, as given his title & affiliation, I figure it's safe to assume that he knows his stuff.)
Here's what he has to say about it:
"Botrytis blight or grey mold is probably the most persistent and potentially damaging problem in poinsettia production because it can cause extensive damage to all to all phases of production. Botrytis can infect all above-ground parts of the poinsettia plant and is usually readily seen as a fuzzy grey-to- brownish growth on infected plant tissue. Poor air circulation/air stagnation, poor sanitation practices, tissue stress or wounding, and wet tissue all favor the development of Botrytis infection. Infection can occur rapidly and can devastate a crop in a short period of time under favorable conditions. Stressed cuttings under mist, plant crowding, and leaf and bract weakened by nutritional stress or excessive soluble salts all favor Botrytis development. Mature cyathia are especially vulnerable to Botrytis infection and the plants usually do not remain in the production greenhouse at this stage of production."
As for detecting Poinsettia disease by looking at the roots, Dr. Barnes offers the following:
"The most consistent and serious disease problem at this (Late Production) stage of poinsettia production is Pythium root rot. Symptoms usually become apparent when plants wilt, either rapidly or slowly with associated poor growth. Examination of the root system shows blackened, deteriorated roots, with a mushy consistency."
For the complete article, read:
Poinsettia Disease Primer by Dr. Larry Barnes Also, thanks to funnyfarmresident for alerting us to what to look for when buying our plants this year. (It never occured to me to look past the glitter & the pretty packaging! Maybe I can chose a healthy 1 this time, & keep it alive!)