Department of Plant, Soil and Microbial Sciences Weeds

Eastern Black Nightshade (Solanum ptycanthum Dun.)
Life cycle:
Summer annual. Emerges in the spring sets seed in late summer/fall and dies.

Emergence:
Eastern black nightshade (EBN) emerges after common lambsquarters and the ragweeds. Ten percent emergence is seen between 250-400 GDD (base 48 deg F); 25% emergence by 282 GDD (base 50 deg F).

Emerges from soil depths of less than one inch.

Seed:
Production Average: 10,000 seeds/plant. Each plant produces between 50-100 berries, with each berry containing about 100 seeds.

Dispersal Mechanisms: Birds eat EBN berries and disperse the seed over wide distances.

Longevity: EBN has very persistent seed. It was estimated that 90 percent of the seed would remain in the soil after 5 years. However, after 3 more years, only 2 percent of the seed was viable.

Dormancy: EBN is less dormant with the seed is located in the upper inch of the soil profile. As burial depth increases, seed dormancy increases.

Competitiveness:
EBN is not a strong competitor with crops, but the weed is shade-tolerant. Densities of two plants per foot of row reduced yield of soybean (planted at 150,000 plants/A in 30" rows) by 10% in 1 of 3 years. Nrrow row spacing in soybean reduces nightshade growth and berry (seed) production.

Preferred Soil / Field Conditions:
This weed grows well on soils rich in N, P, K.

Management:
Biological
Birds and mice predate EBN seed. Thus far little information is available on EBN seed predation by insects.

Mechanical
Tillage: Tillage at night (in the dark) reduces EBN emergence by 50-75%.

Rotary hoeing: EBN is easily controlled with a rotary hoe when it is less than 1/4 inch in height.

Flaming: Flaming is effective in controlling small EBN seedlings.

Cultural
Crop rotation: EBN is seldom a weed of small grains or forages.

Planting date: Tilling in the spring and planting later (mid-May) may reduce night shade infestations, but nightshade has a very long emergence period is soil moisture is available.

Row spacing: Planting soybeans in 7.5" rows reduces nightshade growth and berry production and is recommended for managing this weed.

Harvest: Combine late to avoid staining of soybeans by berries. Many berries will have fallen to the soil surface, and the ones remaining on the plants will be very close to the soil surface. 

Chemical
EBN is one of the more difficult weeds to control in soybean and sugar beets. EBN starts emerging early and continues to emerge through June if moisture is available. Small seedlings will survive in the shade under crop canopies.