Pythium Fungus

Pythium has historically been classified as a common fungus found in soil, sand and water.  It is now classified as a parasitic oomycete but is still commonly referred to as a “water mold”.  Pythiumroot rot will rot the base of unrooted cuttings and can be introduced with dirty tools, pots or flats. Wide varieties of plants are susceptible to the fungus although young or succulent plants are at the most risk.   High soil moisture, high soluble salts and poor aeration are conditions which promote root rot pathogens.  A clear indication of an infection on stunted plants is a pattern of wilting at midday with a recovery at night.   Another indication of infection  is brown tissue on the outer portion of the root which will pull off to expose bare vascular tissue.  Left unaddressed, root rot will pass through the plant causing it to yellow and die. 

I have provided a link to an old but thorough article on Pythium Root Rot on Ornamentals written by A.R. Chase  http://bit.ly/5g9mXW