VG08026 Pythium – field day

Pythiums have been described as the “common colds” of plants. They are ubiquitous in vegetable crops and the damage they cause often goes unnoticed except in extreme situations, e.g. damping off disease of parsley seedlings and cavity spot of carrots.

Pythiums are found in all environments including soil and surface water, they are fast growing and reproduce quickly. The disease survive as oospores, root exudates. Pythium is favoured by wet soil conditions with a temperature effect which depends on species.

Unknown factors in the control of Pythium include:

  • pH and soil nutrients
  • Biological control
  • Varietal resistance/ disease tolerance
  • Chemical control with metalaxyl
  • Crop rotation – broccoli in rotation reduced root rot and cavity spot in carrot

The aim of this 3 year project is to determine the role of Pythium in causing root rot and canker; identify predisposing factors to disease and disease control strategies using P. sulcatum and parsnip, parsley & coriander as the model pathogen and hosts.


Liz Minchinton Dolf de Boer
Joanna Petkowski Len Tesoriero
Victor Galea

Pythium root rots of Apiaceae and other vegetables - workshop 2009
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Results :

Parsley dieback

Autumn-Winter 2005 trial showed significant control with Ridomil treatment.

Parsnip canker

Cranbourne West: no difference between treatments and untreated control.

Devon Meadows: no significant difference but Ridomil reduced damage by 25%.

Rosebud: canker reduced by 75% with Ridomil treatment.

Rosebud: soil fumigated and seed coated (Apron XL). Fumigation removes competitors but water moulds like pythium can quickly re-enter.

No effect with Bavistin or Rizolex demonstrates neither Fusarium nor Rhizoctonia are solely responsible for canker

Acknowledgements :

The authors acknowledge the financial contributions from the National Vegetable Levy (AusVeg), Horticulture Australia (HAL) and the Federal Government which made this work possible.

Special thanks to vegetable growers Frank and Angelo Lamattina and Darren Schreurs for providing the field site & crops.

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