Management of Solanum elaeagnifolium in the Mediterranean Basin

Authors: ULUDAG, AHMET - ANATOLIAN AGRICULTURE RESEARCH INSTITUTE; GBEHOUNOU, GUALBERT - FOOD AND AGRICULTURE ORGANIZATION OF THE UNITED NATIONS (FAO); KASHEFI, JAVID - EUROPEAN BIOLOGICAL CONTROL LABORATORY (EBCL); BOUHACHE, MOHAMED - NATIONAL INSTITUTE OF AGRONOMIC RESEARCH OF MOROCCO (INRA); BON, MARIE-CLAUDE - EUROPEAN BIOLOGICAL CONTROL LABORATORY (EBCL); BELL, CARL - UNIVERSITY OF CALIFORNIA; LAGOPODI, ANASTASIA - ARISTOTLE UNIVERSITY OF THESSALONIKI

Submitted to: European Plant Protection Organization Bulletin
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 11/10/2015
Publication Date: 4/1/2016
Citation: Uludag, A., Gbehounou, G., Kashefi, J., Bouhache, M., Bon, M., Bell, C., Lagopodi, A.L. 2016. Management of Solanum elaeagnifolium in the Mediterranean Basin. European Plant Protection Organization Bulletin. 46:139-147.

Interpretive Summary: Silverleaf nightshade (Solanum elaeagnifolium, Cav.), a native plant from the southern USA, has become one of the worst invasive plant species in the Mediterranean Region. Over the last 60 years, the weed has gone from a few accidental introductions to near monospecific populations in many areas of the Mediterranean Basin (especially Greece, Syria and Morocco). It is also invasive in Australia and South Africa. The weed directly causes yield loss of up to 75% in crops such as maize, wheat, cotton and sorghum, and it indirectly harms crops by harboring plant pests and pathogens. The weed is toxic to livestock and it releases toxins in the soil that inhibit growth of some cultivated plant species. Other losses of resource or revenue caused by its invasion include decreased forage quality on grazing lands; decreased usability of cropland and public space; increased water loss; increased water irrigation costs; and increased forest restoration costs. Available control techniques need to be improved to reduce its impact and prevent its spread. More attention needs to be devoted to biological control, which has already proven effective in South Africa and which could provide regional management of this invasive alien plant. Sustainable management will require coordination, education and support across the affected countries. Governments need effective means to detect, manage and control this weed.

Technical Abstract: Solanum elaeagnifolium Cav. (silverleaf nightshade, SOLEL) is a prominent invasive alien weed in many countries of the Mediterranean Basin since its introduction in the mid-20th century, originating from the southwestern United States and northern Mexico. It reproduces vegetatively and by seeds that disperse in hay, water or by animals, or by movement of soil. It is a perennial plant that can regenerate from small root fragments, so cultivation tends to spread it rapidly. The weed is poisonous to some livestock, and it produces toxins that inhibit growth of desirable plants, including crops. The weed occupies arable, pastoral, urban and suburban areas over a wide geographic range that is likely to increase under climate change. Infestations are serious in both unirrigated and irrigated croplands, creating a serious threat to the Mediterranean basin where water availability is a critical issue for agriculture and people. The use of herbicides and mechanical removal can be effective but are uneconomical for controlling large and dense infestations. There is a critical need to develop sustainable effective methods to control the weed. Classical biological control, the introduction of naturally occurring host-specific insects, has already proven effective in South Africa. In 2013, several organizations involved in SOLEL research and management throughout the Mediterranean Basin agreed to work together to develop a strategy for managing SOEL in the region. Here we present a review of the current status of the SOLEL invasion, and document its threats to agriculture, ecology and human welfare in this region. We also identify knowledge gaps and current research needs, including mapping, biological control, chemical control, prevention and early detection.