Recent introductions of weeds in Tunisia
The flora of Tunisia counts nearly 1400 native plants. Approximately 1000 introduced species have become naturalized in natural and artificial ecosystems. Some of these species have been introduced recently and pose a serious problem to Tunisian agriculture. Among these species, the following are described, with their situation in Tunisia:
- Bidens tripartita (Asteraceae) originates from Eurasia and is considered a weed in many crops. It is recorded in citrus orchards in Tunisia where it currently does not exhibit invasive behaviour.
- Cuscuta australis (Convolvulaceae) originates from North America and has a worldwide distribution. In Tunisia, the species is widespread and parasitises both cultivated and wild plants, causing negative impact on crops, in particular vegetables.
- Cyperus bulbosus (Cyperaceae) is native to Australia and is considered a weed where it has been introduced (e.g. India, Kenya). In Tunisia, the species is widespread in olive orchards in the Sahel region.
- Datura ferox (Solanaceae) originates from Asia and is now widespread in the Mediterranean Basin. In Tunisia, the species has invaded vineyards in Cap Bon where it is difficult to manage with herbicides. It has also invaded riverbeds and orchards.
- Eleusine indica (Poaceae), native to the tropics and subtropics, has a worldwide distribution (including the EPPO region) and it is known as a weed. It was recently found in a pomegranate (Punica granatum) orchard in Tunisia.
- Galinsoga parviflora (Asteraceae) originates from South America and is reported in Australia, Europe, the Mediterranean Basin, Africa and Asia. In general it is considered as a weed, particularly of vegetable crops. An outbreak of the species has been reported in a citrus orchard in Cap Bon.
- Ipomoea imperati (Convolvulaceae) originates from southern North America. In the EPPO region, the species has a limited distribution (prior to this record, it was only recorded in Spain and the Azores). In Tunisia, the species occurs in sand dunes. Although not posing a problem to agriculture so far, its progression should be monitored.
- Nothoscordum gracile (Liliaceae) is an ornamental plant originating from South and Central America and recorded in the Mediterranean Basin. In Tunisia, its distribution is still limited but should be monitored as the species could be spread with plants for planting as a contaminant of their growing media.
- Oxalis articulata (Oxalidaceae) is native to South America and occurs in Mediterranean countries. In Tunisia, it escaped from gardens and can be a problem in nurseries, from which it could spread with plants for planting accompanied by growing media.
- Salpichroa origanifolia (Solanaceae) is native to South America and occurs in the Mediterranean Basin. The species has been introduced as an ornamental plant in Tunisia and has escaped into arable fields where it is a weed.
- Solanum elaeagnifolium (Solanaceae, EPPO A2 List) originates from the Americas, and is present and considered a weed in the 5 continents. In Tunisia, the plant was first collected in 1989 in the Kairouan region, and has since spread to the whole governorate, in particular orchards, arable fields in particular vegetable.
Omezine A (2011) Introduction récente de certaines adventices des cultures en Tunisie. Bulletin OEPP/EPPO Bulletin 41(1), 77-84.