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 considered a highly invasive plant 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] with sticky glandular hairs that give off a strong aromatic odor that is easily recognizable [1,2,4]. Stinkwort has flowers with 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 habitats 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]. 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 a few different ways in which stinkwort seeds can be dispersed. The seeds have small fine hairs which allow 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 increased mortality rates [1,4]. The fine hairs of the seed can 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 it is also problematic for humans. When stinkwort is flowering and makes contact with 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 like pulling, hoeing, and mowing can be used [1,4]. When hand pulling and hoeing, gloves should be worn to avoid dermatitis. Mowing is only a partial control and should be done multiple times late in the season [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, 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