U.S., Greece Collaborate on Invasive Weed Defense

Silverleaf nightshade (U.S. Bureau of Land Management)

One U.S. export not appreciated overseas is the silverleaf nightshade, an invasive weed from the Americas that has spread to southern Europe, Africa, India, Australia, and elsewhere. The Agricultural Research Service (ARS) of the U.S. Department of Agriculture and the Benaki Phytopathological Institute in Athens, Greece are working together to find a natural way to counter this unwelcome visitor.

Silverleaf nightshade (Solanum elaeagnifolium) is a perennial weed that can overtake native plants, reduce crop yields, and diminish pasture productivity. Its orange, toxin-producing berries can also poison livestock. Severe infestations of the weed can make normal chemical or mechanical controls, like mowing, too costly, impractical, or environmentally harmful to use.

The ARS Biological Control of Pests Research Unit in Stoneville, Mississippi and the Benaki institute are seeking out the silverleaf nightshade’s natural enemies to counter the spread of the weed. These natural enemies are typically insects — insects, mites, microbes or nematodes — that severely damage or kill targeted weeds, but spare useful plants, explains Walker Jones, an ARS entomologist.

The project is still in its early stages. The work now involves include genetically analyzing silverleaf nightshade populations collected worldwide and physically mapping Greece’s infestations of the weed and densities using satellite photographs.

The joint project is reported in the the November-December 2010 issue of Agricultural Research magazine.

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