Phonetic: Pie-thee-umm

This fungus is a widespread saprobe in warmer areas and is found on plant debris, dead organic material, grasses, soil, roots, fruits, water, and as a parasite on seedlings. This genus may cause diseases such as damping-off, foot rot, and pre-emergence killing. Approximately 60 of the 120 species are considered to be plant pathogens. Pythium can live saprophytically, but can survive in dry soil for years. It is more frequent in cultivated soils and appears to be intolerant of acidic conditions. This genus is a primary colonizer of untouched substrates and gains an advantage because of its rapid growth. However it does not compete very well with other fungi that have already colonized a substrate. This genus includes a species considered to be a mycoparasite, P. oligandrum, which can be used as a biological control agent. The species P. insidiosum is the causative agent of Pythiosis Insidiosi, or “swamp cancer” especially in horses and mules, in wet tropical areas. The same infection has been reported in cattle, dogs, and cats. It is rare in humans, but farmers with exposure to swampy areas have succumbed. It is characterized by tumor-like masses that develop mostly on the legs. Lesions eventually ulcerate and drain, bones can also become involved. Pythium can be controlled by the bacterium Pseudomonas and Streptomyces (A_w -0.90) Culture - Potato dextrose agar or Malt extract agar, 20° – 25°C, 7 – 10 days.