Stinkwort (Dittrichia graveolens)
Taxonomy
Domain: Eukaryota
Kingdom: Planteae
Phylum: Tracheophyta
Subphylum: Angiosperms
Class: Magnoliopsida
Order: Asterales
Family: Asterceae
Subfamily: Asteroideae
Genus: Dittrichia
Species: D. graveolens
Description
Dittrichia graveolens or stinkwort belongs to the Asteraceae family which consist of flowering plants [1]. Stinkwort is an invasive species that has found its way into many areas. It is also considered a noxious weed since it has the potential to harm horticultural crops, natural habitats, ecosytems, humans, and livestock [1,2,4,5]. Annually flowering in the fall, stinkwort is erect growing up to 2.5 feet [1,2,3,4,5]. Sticky glandular hairs of the stinkwort give off strong aromatic odor that is easily recognizable [1,2,4]. Stinkwort has flowers that have short yellow rays on the outer edge and yellow to red disk flowers in the center [1,2,4]. Stinkwort which is native to the Mediterranean is rapidly invading other areas. It has found its way into many other areas including Central Europe, Australia, South Africa, and the United States [1].
Habitat
Stinkwort can be found in a variety of places located around its native area. It is known to be prevalent in riparian woodlands, margins of tidal marshes, vernal pools, and alluvial floodplains [1]. However, in areas where stinkwort is not native, it grows in disturbed areas such as overgrazed rangelands, roadsides, pastures, wastelands, vineyard edges, gravel mines, levees, washes, and mining sites [1,2]. Well-drained, sandy and gravelly soils are where Stinkwort thrives. Hot and dry climate is its preferred area, but grows well on the outskirts of wetlands.
Seed Dispersal
There are few different ways in which stinkwort seeds can be dispersed. The fine hairs of the seeds allows for wind dispersal [3]. The fine hairs also stick to clothing, wool, hair, and machinery [3]. Stinkwort seeds have high viability with about 90% of the seeds being capable of germination at the time of dispersal [1].
Negative Impacts
Stinkwort is not an edible species so it can cause problems within livestock. If consumed by livestock, stinkwort can poison them leading to mortality in some cases [1,4]. The fine hairs of the seed induce enterotoxaemia (pulpy kidney) or release fatal bacterium if the livestock have chosen to graze on it [4]. Not only does it cause problems in animals, but also humans. When stinkwort is flowered and then handled by bare skin, it can cause severe dermatitis [4,5].
Control
There are several different ways in which stinkwort can be controlled. For smaller areas of invasions, mechanical practices can be used. This involves pulling, hoeing, and mowing [1,4]. When hand pulling and hoeing, gloves should be worn to avoid dermatitis. Mowing is only a partial control. It should be done late in the season and multiple times [1]. The buds remaining may grow back, which is why this should be repeated more than once [1]. For larger areas two different types of herbicides can be used. The two types being either post or preemergence herbicides. Postemergence herbicides are applied to young plants and target visibly infested areas [1]. Preemergence herbicides are used for larger areas before seeds are allowed to germinate [1].
References
[1] Brownsey, R., Kyser, G.B., DiTomaso, J.M., 2013. Stinkwort is rapidly expanding its range in California. Cal Ag 67, 110–115. https://doi.org/10.3733/ca.v067n02p110
[2] Brownsey, R.N., Kyser, G.B., DiTomaso, J.M., 2014. Growth and phenology of Dittrichia graveolens, a rapidly spreading invasive plant in California. Biol Invasions 16, 43–52. https://doi.org/10.1007/s10530-013-0501-4
[3] Kocián, P., 2015. Dittrichia graveolens (L.) Greuter – a new alien species in Poland. Acta Musei Silesiae, Scientiae Naturales 64, 193–197. https://doi.org/10.1515/cszma-2015-0027
[4] Stinkwort Guide [WWW Document], n.d. . HerbiGuide. URL http://www.herbiguide.com.au/Descriptions/hg_Stinkwort.htm
[5] Thong, H.-Y., Yokota, M., Kardassakis, D., Maibach, H.I., 2007. Allergic contact dermatitis from Dittrichia graveolens (L.) Greuter (stinkwort). Contact Dermatitis 58, 51–53. https://doi.org/10.1111/j.1600-0536.2007.01154.x