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Pythium root rot

© Iowa State University

Pathogen(s) causing disease:

Pythium (multiple species)


Infected plants have dark areas extending up the stem several inches from the soil line. The diseased areas usually become translucent, soft and watery.


The fungi survive in soil and plant residue. When the soil is cool (50 to 59 F, 10 to 15 C) and wet, the bacteria commonly germinate.


Plant high-quality, crack-free seed capable of at least 85% germination in a warm or standard test and 70% in a cold test. Plant in warm soil (above 65 F, 18 C) that is well drained and fertile and well prepared. Where feasible, turn under weeds or cover crops several weeks before planting. Apply a seed treatment or soil-applied fungicide. Fungicide seed treatments will often increase emergence, especially when conditions do not favor seedling growth and development. Do not plant carryover seed. Avoid excessive irrigation for the first 10 to 15 days after planting.


U of IL

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