Pythium (Pythium spp.)

Pythium: biology

Pythium species are organisms which behave similar to fungal root pathogens, spreading through wets or waterlogged soils. Pythium enters through the seed, seedling or roots, typically affecting young plants. Pythium spp. can cause seed rot, pre-emergence damping-off, and seedling blight. It can also affect the root resulting in post-emergence damping-off.

Pythium: damage description

Pythium

Seeds and young seedlings infected below and above ground will become soft, turn brown, and disintegrate. Plants surviving an early infection may exhibit reduced vigor and growth which present as a random or patchy plant stand.

Pythium: management

Pythium spp. are most damaging in wet and waterlogged soils as they can produce a large number of mobile spores which multiply and spread infection across the field. Multiple pathogenic Pythium species can coexist in any one field and the optimal temperature for infection varies between species.

Because Pythium persist in wet and warm soil, seeding into cool soils will improve yield outcome.

Because the symptoms are similar to other pathogens which co-exist as a root rot complex, laboratory confirmation may be required to determine cause of infection. In fields with a disease history or when planting in wet and cool conditions, it is recommended to use seed treatment with Pythium on the label.

Resources

The impact of Pythium on seedling growth

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