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Black Nightshade

Black Nightshade

Solanum nigrum

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Black nightshade

DESCRIPTION

Note: Black nightshade is often mistakenly called deadly nightshade. It’s not deadly nightshade …see ‘Toxicity’ below.

Black nightshade is a summer annual and can be a short-lived perennial. It can be variable in size and form, but most often grows as a tall, upright plant reaching about 70cm in height. Large plants will typically become extensively branched and can carry a lot of foliage and consequently compete successfully with crop and pasture species for sunlight. The plants normally die-off with the late autumn frosts. The leaves are dark green, sometimes with purple edges, oval-shaped and pointed at the tips, and are up to 12cm long by 7cm wide. The stems are often distinctly purple, especially late in the season.

Mature plants support distinctive bunches of berries 7-10mm in diameter, initially green in colour and turning to black when ripe. When green the berries are a serious problem in pea crops because they can easily be harvested with the peas and are hard to distinguish visually.

Flowers appear between October and May, and are generally white, occasionally pale mauve, 10- 12mm in diameter, with five pointed petals and a central yellow column.

Distribution

Black Nightshade is common throughout most of NZ, although less so in the southern half of the South Island. It appears most often in arable land, waste areas, disturbed pastures and gardens. The ripe berries are eaten by birds and it is by this means (bird droppings) that the plant is most readily spread.

Toxicity

Black nightshade is not particularly poisonous, although the unripe green berries may be mildly toxic to children, and there are observations of calves being ‘drunk’ from eating black nightshade that has become more palatable as it dies off after spraying. Its undeserved reputation for toxicity is largely due to its being regularly mistaken for deadly nightshade. Deadly nightshade is actually very rare in NZ, and exists only in very limited numbers in locations close to Christchurch.

Deadly nightshade (also called belladonna) is indeed highly toxic: Emperor Augustus was poisoned by his missus with belladonna, and Macbeth used it to poison various Englishmen.

CULTIVATION CONTROL

Black nightshade is controlled by cultivation where that is an option. However, it does commonly appear in new pasture and crops, when other control measures must be used.

HERBICIDE CONTROL OF BLACK NIGHTSHADE

Black nightshade is readily controlled by many herbicides, so the most suitable product to use is generally determined by the situation and the need to avoid or minimise damage to pasture and crops.  However, there is evidence of black nightshade resistance to some chemicals, particularly chlorsulfuron, metsulfuron (MSF600) and the triazine family of herbicides.

Herbicide Paste or Gels to Kill Black Nightshade

You can use any of the Glyphosate based Cut’n’Paste gels.  Original, Bamboo Buster or Glimax. Apply the gels on the underside of the leaves or if the stems are thick enough cut the stem close to the ground and apply to the cut surface and a little down the stem.

Black Nightshade Herbicides to use in Waste Areas
Black Nightshade Herbicides to use in New Pasture
  • PastureMate at 3-4L/ha. Good control in seedling stage (2-3 leaves). Useful suppression at later growth stages. Will not damage new grasses or clover.
  • Rainbow & Brown MCPA750, applied by boom spray at 4L-6L per hectare, are effective against black nightshade at the seedling stage, and will not damage the new grasses or clover.
  • WHACK – 2,4-D 800 at a maximum of 1.5-2kg/ha (or 1.1L/ha if red clover has been sown).  Clover needs to be at least 3 trifoliate leaves and pasture needs to be grazed 3-7 days before application to remove foliage and minimise clover damage.  Soil need to have adequate nitrogen status.  Clover growth will be suppressed for 3-4 months.

These products will also provide reasonable suppression of plants past the seedling stage.

Black Nightshade Herbicides to use in Established Pasture
Black Nightshade Herbicides to use in Clover, lucerne, chicory, and maize crops
  • PastureMate in White Clover Seed Crops at 3-4L/ha in 150-250L of water. Apply in spring to actively growing seedling weeds. Not to apply after clover has commenced flowering.
  • Decision at 50g/Ha, applied before 4th leaf stage. For larger black nightshade, increase rate to 65g/ha. For best results add BioWet  crop oil at 500ml/100L water.
  • In Maize - 400-600ml Dicamba 500 Select in 200 litres water per hectare.  NOTE.  Dicamba will kill clover.
Use a Weed Wiper to Kill Black Nightshade

If above the level of your pasture weed wiping with Glyphosate is also a good option. You should end up applying the following mixes at about 10L/HA on light infestations and 20L/HA on heavy infestations.