Helicobasidium purpureum

Helicobasidium purpureum is a fungal plant pathogen which causes violet root rot in a number of susceptible plant hosts. It is synonymous with Helicobasidium brebissonii (Desm.) Donk. It is the teleomorph of Tuberculina persicina which is its mycoparasitic anamorph.[2]

Helicobasidium purpureum
Helicobasidium purpureum on carrot (Daucus carota)
Scientific classification
Kingdom:	Fungi
Phylum:	Basidiomycota
Class:	Pucciniomycetes
Subclass:	Incertae sedis
Order:	Helicobasidiales
Family:	Helicobasidiaceae
Genus:	Helicobasidium
Species:	H. purpureum
Binomial name
Helicobasidium purpureum (Tul.) Pat. 1885
Synonyms[1]
Corticium sanguineum var. lilacinum Helicobasidium brebissonii (Desm.) Donk, (1958) Hypochnus purpureus Protonema brebissonii Rhizoctonia asparagi Rhizoctonia crocorum Rhizoctonia medicaginis Rhizoctonia rubiae Rhizoctonia violacea Rhizoctonia violacea f. dauci Sclerotium crocorum Thanatophytum crocorum Tuber parasiticum

Varieties

There are three varieties:

• Helicobasidium purpureum var. barlae Bres. 1909
• Helicobasidium purpureum var. orientalePat. 1920
• Helicobasidium purpureum var. purpureum(Tul.) Pat. 1885

Distribution

Helicobasidium purpureum has a cosmopolitan distribution and is found in all regions in which its host plants grow.[3]

Host plants

In the United Kingdom, colonies of Helicobasidium purpureum have been found on the living stems of dog's mercury (Mercurialis perennis) and stinging nettle (Urtica dioica). The fungus is also associated as a saprobe with decaying wood and stumps of broad leaf trees. Its rhizoctonian anamorph infects the roots of carrot (Daucus carota), parsnip (Pastinaca sativa), swede (Brassica napus ssp rapifera), turnip (Brassica rapa), celery (Apium graveolens), asparagus (Asparagus officinalis), beetroot (Beta vulgaris), potato (Solanum tuberosum) and sea kale (Crambe maritima).[4] Wild plants on which it has been found felting the roots with purple or brown mycelium include chickweed (Stellaria) spp., sow thistles (Sonchus) spp., nettles (Urtica) spp., shepherd's purse (Capsella bursa-pastoris) and yarrow (Achillea millefolium).[4]

Symptoms

In susceptible crops, any parts below the ground are liable to infection. The mycelium of the fungus forms a matted, felt-like purple covering which grows over the surface of the root. Soil particles adhere to this and small, dark-coloured sclerotia grow among the hyphae. A dry rot occurs and secondary rots may move in.[5] Mycelial threads, often merging into strands, grow through the soil and infect nearby plants. A pink or brown mat of mycelial threads may grow above the soil surface. In affected plants, the aerial parts may wilt and have discoloured, stunted foliage.[5][6]

Control

Violet root rot chiefly occurs in waterlogged, acid soils. These conditions can be improved by choosing a well-drained location to grow root crops and liming the soil. Individual affected plants can be removed and destroyed. The mycelium and sclerotia remain infective for some time and the ground should not be used again for root crops for at least four years. In the interim, susceptible weeds should not be allowed to grow.[5]

References

1. Kew Mycology (2011). "Helicobasidium purpureum (Tul.) Pat". Species Fungorum. Index Fungorum. Retrieved 2013-04-10.
2. "Helicobasidium purpureum Pat. syn.: Helicobasidium brebissonii (Desm.) Donk". Tree of Life Web Project. 2006. Retrieved 2013-04-10.
3. "Helicobasidium purpureum Pat. 1885". Fungal Databases, Systematic Mycology and Microbiology Laboratory. ARS, USDA. 2010-05-19. Retrieved 2013-04-10.
4. "Helicobasidium purpureum (Tul.) Pat., 1885 (Violet Root Rot - causative organism)". BioInfo UK. Retrieved 2013-04-10.
5. Brickell, Christopher (ed) (1992). The Royal Horticultural Society Encyclopedia of Gardening. Dorling Kindersley. p. 565. ISBN 9780863189791.CS1 maint: extra text: authors list (link)
6. "Carrot (Daucus carota)-Violet Root Rot". Pacific Northwest Plant Disease Management Handbook. Archived from the original on 2015-06-10. Retrieved 2013-04-10.