Nightshade, eastern black, Solanum ptycanthum

Life Cycle

Annual

Propagation

Reproducing only by seed.

Stems

Stems erect, 5 - 100 cm high, usually much-branched in the upper part, mostly hairless.

Leaves

Leaves alternate (1 per node), ovate or rhombic (diamond-shaped), pale green, soft, thin and nearly translucent.

Flowers and Fruit

Flowers small, usually 2 to 5 grouped together in a small umbel (flower stalks all from 1 point) (a) on a short stalk sticking out from the side of the stem (b) rather than from the axil of a leaf (angle between leaf and stem) as in most other plants; calyx of 5 united sepals with 5 pointed lobes, small and not enlarging with the fruit (c); petals white or white tinged with purple, united into a star-shaped corolla with 5 sharp lobes resembling the flower of a potato but much smaller, about 9 - 15 mm in diameter; the short anthers (d) about 1.3 - 2 mm long, united and forming a yellow column in the centre of the flower; fruits are berries, always larger than the calyx, green at first but turning dark brown to black and juicy when mature, 5 - 9 mm in diameter, containing several, small, flat seeds and 4 to 8 small, hard, irregular stone-like crumbs. Flowers from June until late autumn.

Roots and Underground Structures

Slender taproot with a branched fibrous root system.

Habitat

Eastern black nightshade occurs throughout southern Ontario in open dry woods, edges of pastures, waste places, and in cultivated land, especially in row crops.

Competitiveness

Corn yield loss (%)*: 2 % at 1 plant/m2 7 % at 5 plant/m2 Soybean yield loss (%)*: 14 % at 1 plant/m2 40 % at 5 plant/m2 *assumes that the weed has emerged with the crop and has been left uncontrolled all season.

Distinguishing Features

It is distinguished by being annual plant with thin, ovate to diamond-shaped leaves, small umbels of flowers on short stalks from sides of stems (not from leaf axils), small, white flowers, and small, black berries that are not partly enclosed by their expanded calyxes.

Toxicity

The berries of Eastern black nightshade are reputed to be poisonous and thus the plant is sometimes called “deadly nightshade,” a name belonging to a different plant. Until more information is available about their palatability, it is advisable not to eat these attractive berries.

Human Health Issues

See notes on toxicity.

Forage Quality

Feeding experiments have demonstrated that this plant can be toxic to cattle if it comprises about 25% or more of the forage intake.

Notes

No information available at this time.

Species Benefits

No information available at this time. See notes on toxicity.

Often Mistaken For

Pigweed spp.

Power Ranking Corn

Power Ranking

↑ 23

 

Power Ranking Soybeans

Power Ranking

↑ 7

 

Biological Control

Currently none available for this weed. For the latest research on biological weed control: http://res2.agr.ca/Lethbridge/weedbio/index_e.htm#toc

Biopesticide Control

Currently none available for this weed in corn and soybean.

Herbicide Resistance

Sulphonylurea and imidazolinone resistant (WSSA group 2) populations exist in Bruce, Elgin, Huron and Middlesex counties (ON). For more information on weed resistance: http://www.plant.uoguelph.ca/resistant-weeds/


Figure #1.

Eastern black nightshade: A. Upper part of plant. B. Portion of annual root system.


Figure #2.

Seedling at the 2-leaf stage.


Figure #3.

A 3 leaf eastern black nightshade seedling. The maximum leaf stage to achieve control with many post emergent soybean herbicides


Figure #4.

Easter black nightshade leaf.


Figure #5.

Eastern black nightshade flower.


Figure #6.

Imature green fruit, which will eventually turn black.


Figure #7.

Mature Plant.


Figure #8.

Mature black berries found in an Ontario soybean field during October. The berries will stain the soybean seed and reduce quality.