How can you tell the difference between pythium and rhizoctonia? And what is the latest method of treatment? This is for Prestige Red Poinsetties. Thank You. Tom W.

Tom, This is definitely not a scientific way to diagnose fungus problems on Poinsettias but....visually pythium and phytophtora usually show up as dark brown discolored roots as in the picture below where as Rhyzoctonia generally creates a brown leasion on the main stem right at the soil line......Michael Pawelek

This page will give you current chemicals and the fungus they will treat.....
Disease recommendations...

This message has been edited. Last edited by: Michael Pawelek,

The only way to make a definitive diagnosis would be to have material tested. This can be done at a local university with a plant pathology lab. If you don't know of a local lab you can check with your local extension agent for suggestions.

Are you seeing symptoms on the roots or stem tissue of the plant? Generally pythium begins in the roots while rhizoctonia starts on the stem tissue and most often with a lesion at the base of the soil line. Sometimes lesions can begin farther up on the stem.

Again, testing is the only way to tell for sure but most fungicides used to treat pythium and phytophthera and also be used to treat rhizoctonia and vice versa.

Try Poinsettia Federal Disease Control Chart (292K PDF) for a complete listed of chemicals labeled for control of the water molds.