Stinkwort (Dittrichia graveolens)
Description
Dittrichia graveolens or stinkwort belongs to the Asteraceae family which consist of flowering plants [1]. 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 a yellow to reddish 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 many other areas including Central Europe, Australia, South Africa, and the United States [1].
Habitat
Stinkwort can be found in a variety of places in 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].
Seed Dispersal
There a few different ways in which stinkwort seeds are dispersed. The fine hairs of the seeds allow for wind dispersal [3]. It also sticks to clothing, wool, hair, and machinery [3]. Stinkwort seeds have high viability. About 90% of the seeds are capable of germination at the time of dispersal [1].
Negative Impacts
Stinkwort is not a palatable 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 pulpy kidney or a fatal bacterium if grazed by livestock [4]. It does not only cause problems in animals, but also humans. When stinkwort is flowered if it is 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. Mowing should be done late in the season and multiple times [1]. The buds remaining may grow back however which is why this should be conducted more than once [1]. For larger areas herbicides can be used. There is 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 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