- Worldwide distribution. Several types. On taro and Xanthosoma, but also on bean, capsicum, ginger, peanuts and pineapple, and weeds; causes a damping-off disease (see Fact Sheet No. 47). An important disease.
- A water mould, an oomycete, not a fungus. Worse in wet soils.
- Roots infected; leaves wilt, become stunted, with only one or two leaves remaining. Corm yields are low; post-harvest rots occur.
- Cultural control: clean 'tops' of roots and soil; avoid areas that flood, or where water remains for several days; plant on raised beds with surrounding ditches; grow e.g., Mucania or Pueraria before taro to build organic matter content of the soil; add lime (20g/m2) to increase calcium; >3-year crop rotation; collect debris and burn after harvest.
- Chemical control: none recommended.
Pacific Pests, Pathogens, Weeds & Pesticides
Taro root rot (044)
Photo 1. The beginning of symptoms on cocoyam, Xanthosoma, showing early death of the older leaves caused by Pythium sp. (Solomon Islands.)
Photo 2. Pythium infection in Colocasia taro showing weak-looking plants with two at most three leaves, and new leaves which are stunted and partly rolled. (Samoa.)
Taro root rot, cocoyam root rot, Pythium root rot of taro (cocoyam)
AUTHORS Helen Tsatsia & Grahame Jackson
Information from Jackson GVH, Gerlach WWP (1985) Pythium rots of taro. South Pacific Commission. Noumea, New Caledonia. (https://lrd.spc.int/component/docman/cat_view/137-all/128-plant-health-/276-pest-advisory-leaflets?start=30); and Ooka JJ (undated) Taro diseases. Research extension series. Hawaii Institute of Tropical Agriculture and Human Resources. Honolulu. Hawaii. (https://core.ac.uk/download/pdf/5095157.pdf); and from Carmichael A, et al. (2008) TaroPest: an illustrated guide to pests and diseases of taro in the South Pacific. ACIAR Monograph No. 132, 76 pp. (https://lrd.spc.int/about-lrd/lrd-project-partners/taropest); and from Biosecurity Australia (2011) Review of import conditions for fresh taro corms. Biosecurity Australia, Canberra. (https://www.agriculture.gov.au/sites/default/files/sitecollectiondocuments/ba/plant/2011/taro/Review_of_Import_Conditions_for_Fresh_Taro_Corms_clean.pdf). Photo 3 William Wigmore and Maja Poeschko, Ministry of Agriculture, Cook Islands.
Produced with support from the Australian Centre for International Agricultural Research under project PC/2010/090: Strengthening integrated crop management research in the Pacific Islands in support of sustainable intensification of high-value crop production, implemented by the University of Queensland and the Secretariat of the Pacific Community.