Description:
Silverleaf nightshade is a branched, deep-rooted, perennial herb,
1 to 4 feet tall. Slender, yellow spines occur on the stems or leaf
ribs of the plant. The lance-shaped leaves are 1 to 4 inches long
by 1 inch wide, with wavy margins; they are covered with short,
silvery-white, star-shaped hairs that give the plant a dusky or
silvery-gray color. The blue, violet or rarely white flowers have
5 fused petals, 3⁄4 inch across, with bright yellow stamens.
Flowers grow on stalks in clusters or singly at the end of stems
or branches. The fruits are yellow to brownish, juicy berries, 1⁄2
inch in diameter. Seeds are flat, brown and 1/10 to 1/5 inch long
(Boyd et al. 1984; Gunn and Gaffney 1974; Roche 1991; Rutherford
1978).
- Mechanical:
Plants can regrow after being clipped (Cooley and Smith 1971).
Removing plant tops by mowing results in a loss of apical dominance
that causes multiple shoots to re-sprout (Boyd and Murray 1982b).
Removing above-ground parts every 2 weeks can prevent seed production
(Roche 1991).
- Biological:
In Arizona, New Mexico, and Texas, part of the plant’s native
range, 116 insects were collected on silverleaf nightshade. However,
it is still weedy in these areas (Goeden 1971). Several biocontrol
agents have been investigated. The most promising organism is
a foliar nematode, Orrina phyllobia, which causes leaf and stem
galling (Roche 1991).
- Herbicide:
The plant is difficult to control with herbicides because the
root system is widespread and connects to adjacent above-ground
growth (Richardson 1979). Studies in California and Greece indicated
that glyphosate and picloram provide consistent control of this
weed (Eleftherohorinos et al. 1993). California growers have used
soil fumigation to eradicate small infestations (Roche 1991).
For specific herbicide recommendations, refer to the Pacific Northwest
Weed Control Handbook. Refer to the State
Noxious Weed Control Board site
For More Information:
Detailed information about Silverleaf
Nightshade is available at the Washington State Noxious Weed
Control Board Web Site. |
