Senecio

Senecio

Ragworts
Genus:	Senecio
Family:	Asteraceae
Weediness:	Some species are weedy
Pollination:	Insects
Toxicity and edibility:	Some species are toxic to humans and livestock

Senecio is a genus of the daisy family (Family Asteraceae) that includes ragworts and groundsels. Though of late the genus has been reviewed and split up, it still contains a vast number of species (about 1,500) of extremely wide form including leaf succulents, stem and tuber succulents, annuals, perennials, aquatic forms, climbers, shrubs and small trees. Some species produce natural pesticides (especially alkaloids) to deter or even kill animals that would eat them.

Description

The flower heads are normally rayed, completely yellow, and the heads are borne in branched clusters.

Species

• Senecio vulgaris, Common Groundsel
• Senecio jacobaea, Tansy Ragwort

Pests and diseases

Rusts

• Puccinia lagenophorae

Viruses

• Alfalfa Mosaic Virus
• Beet Western Yellows Virus (BWYV, syn. Beet mild yellowing luteovirus or BMYV)
• Potato Virus Y

Maggots

• Leafminer: Phytomyza senecionis
• Leafminer: Phytomyza ovatus
• Tansy seedfly: Pegohylemia seneciella

Flea Beetles

• Ragwort Flea Beetle: Longitarsus jacobaea has been introduced in New Zealand as a biocontrol for Senecio jacobaea.
• Longitarsus ganglbaueri

Caterpillars

• w:list of Lepidoptera which feed on Senecio.
• Cochylis atricapitana
• Phycitodes maritima
• Phycitodes saxicolais
• Saltmarsh Caterpillar: Estigmene acrea
• w:Cinnabar moth: Tyria jacobaeae absorbs alkaloids from the plant and become distasteful to predators, a fact advertised by the black and yellow warning colours. The red and black, day-flying adult moth is also distasteful to many potential predators. The moth is used as a biocontrol for Senecio jacobaea in countries in which it has been introduced and become a problem, like New Zealand and the western United States.

References

• ITIS 36084
• Pink, A. (2004). Gardening for the Million. Project Gutenberg Literary Archive Foundation. {{cite book}}: Check date values in: |year= (help); External link in |title= (help)
• S. rowleyanus at University of Catania
• ICTVdB - The Universal Virus Database, version 4.
• Unuversity of Idaho
• esa
• Royal Society of New Zealand, New hosts of Alfalfa mosaic virus, Cucumber mosaic virus, Potato virus Y, Soybean dwarf virus, and Tomato spotted wilt virus in New Zealand, J. D. FLETCHER
• Forestpests.org
• University of California, Davis