Symptoms and Signs
Pythium disease (also called wilt or stem rot) refers to a disease caused by Pythium aphanidermatum, which occurs when soils are waterlogged and temperatures are high (over 100 °F).Symptoms include rapid wilting of the plant (within 24–48 hours of irrigation) with a sunken brownish lesion on the stem at the soil surface. Discoloration may extend up the stem for 1 to 2 inches.
Occasionally mycelium can be seen at the soil line. It usually occurs when furrow irrigation has covered the bed and is most often found at the head or tail end of the field.
Avoid flood irrigation or furrow irrigation that rises over the top of the bed. Do not irrigate during extremely high temperatures, if possible. Good field preparation and irrigation management can help prevent Pythium disease.