BLACK NIGHTSHADE (Solanum americanum  Miller) Different authorities provide differing accounts of the origination of Black Nightshade: Some claim it is a native species with a worldwide distribution, while others believe that it entered the United States from Europe or South America.

Nightshade cause some of the most serious weed related problems in Pacific Northwest agriculture.The most common members of this family found in PNW cropland are the annuals hairy nightshade (Solanum physalifolium Rusby, formerly S. sarrachoides Sendtner), black nightshade (S. nigrum L.),and cutleaf nightshade.

Cutleaf nightshade, however, is native to the dry regions and has become a serious weed problem in many dryland crop production areas in the PNW.

Crop Damage: Although light infestations of nightshades do not usually cause serious yield losses, heavy infestations will compete with the crop plants for available light, moisture, and soil nutrients. Nightshades can cause serious problems during harvest of several crops, such as green peas and snap beans. The nightshades do not dry as rapidly as many crop plants and are not killed by light frosts in the fall. Heavy nightshade infestations in potato fields may prolong harvest, especially if the potatoes have not been defoliated. Nightshades are also hosts for many plant pests (such as Colorado potato beetle and the late blight fungus) and may cause insect, disease, and nematode problems to increase in potatoes and other rotation crops.

Nightshade is more common in sites with a history  of disturbance. Hairy nightshade and black nightshade look very similar. Nightshade should be correctly identified because some herbicides that effectively control black nightshade are less effective on hairy nightshade. Both cause considerable harvest problems. Hairy nightshade plants appear more upright than black nightshade and the leaves are covered with fine hairs which give the leaf a silvery gray color and may be "sticky" to the touch. Hairy nightshade berries remain green and do not turn purple. Black nightshade is a low-branching annual, 1 to 2 feet tall with triangular stems that bear oval, thin-textured, alternate l eaves. The foliage of Black Nightshade is green or dark green. Nightshade seed germination occurs in June through September and is influenced strongly by moisture. Hairy nightshade germinating in early fall may produce viable seed before frost while a black nightshade plant requires a longer growing season. A single plant may produce flowers sporadically for about 2 months. Each flower is replaced by a small round berry about 1/3" across. The berry has a smooth surface that is initially green, but later becomes black as it matures. This berry is juicy and contains several flat seeds that are yellow or brown. Nightshade seeds become viable shortly after production and can remain viable in the soil beyond 10 years. The root system consists of a slender taproot that branch frequently. This plant spreads by reseeding itself. Nightshades are frost tolerant and stay green into the harvest season.

The caterpillars of the moth Heliothis subflexus feed on this plant, as well as other members of the Nightshade family. The small black berries are eaten primarily by birds, which includes the following: Wood Duck, Sora Rail, Ring-Necked Pheasant, Wild Turkey, Cardinal, Catbird, Eastern Meadowlark, and Swamp Sparrow. These birds help to distribute the seeds far and wide. Mammalian herbivores avoid this plant because the foliage contains the toxic alkaloid, solanine. The plant may be a contaminant in hay, where it will still cause toxicity. Pets may eat the green, red, or black berries and be poisoned. The major toxin is solanine, an alkaloidal glycoside.

Toxicity: Moderate. While the plant itself is very toxic, it is also unpalatable, and rarely does an animal consume enough to cause a serious or potentially lethal poisoning. Toxic risk is higher if the plant is included in processed feeds. All animals, including pets, may be affected. All parts are potentially toxic; some believe the berries are often higher in toxicity.

Symptoms: Nightshade plants cause problems with the gastrointestinal tract and can also affect the central nervous system. Signs can include abdominal pain, vomiting, diarrhea, lack of coordination, weakness, depression, hallucinations, convulsions, and possible death.

Gastrointestinal signs can include: vomiting (in those species that can vomit), poor appetite, abdominal pain, and diarrhea which may become bloody. Central nervous system signs can include depression, difficulty breathing, lack of coordination, weakness, collapse, convulsions and possible death. In one report, one to ten pounds of plant material was potentially lethal for a horse.

A chronic toxicity has also been reported, where the animal eats small amounts of the plants each day. These animals tend to lack energy, show depressive symptoms or get intestinal problems.

Medicinal Uses:  This species has the reputation of being very poisonous, however this is disputed by other resources. The toxin solanine, of which the nightshades are comprised of, vary in concentration throughout the season.

The berries are injurious to children, but are often eaten by adults with impunity, especially when quite ripe, as the poisonous principle is chiefly associated with all green parts. Cattle will not eat the plant and sheep rarely touch it.

In Bohemia the leaves are placed in the cradles of infants to promote sleep. In the islands of Bourbon and Mauritius, the leaves are eaten in place of spinach: and the fruit is said to be eaten without inconvenience by soldiers stationed in British Kaffraria.

It has been found useful in cutaneous disorders, but its action is variable, and it is considered a somewhat dangerous remedy except in very small doses.

The bruised fresh leaves, used externally, are said to ease pain and abate inflammation, and the Arabs apply them to burns and ulcers. Their juice has been used for ringworm, gout and earache, and mixed with vinegar, is said to be good as a gargle and mouthwash.

Besides the above-mentioned species, others are used for medicinal, alimentary, and other purposes. Some are employed almost universally as narcotics to allay pain, etc.; others are sudorific and purgative. Solanum toxicarium is used as a poison by the natives of Cayenne. S. pseudo-quina is esteemed as a valuable febrifuge in Brazil. Among those used for food, are S. Album and S. Æthiopicum, the fruits of which are used in China and Japan. Those of S. Anguivi are eaten in Madagascar. S. esculentum and its varieties furnish the fruits known as Aubergines or Brinjals, which are highly esteemed in France, and may sometimes be met with in English markets; they are of the size and form of a goose's egg and usually of a rich purple colour. The Egg-plant, which has white berries, is only a variety of this. The Peruvians eat the fruits of S. muricatum and S. quitoense; those of S. ramosum are eaten as a vegetable in the West Indies. The Tasmanian Kangaroo Apple is the fruit of S. laciniatum; unless fully ripe this is said to be acrid. In Gippsland, Australia, the natives eat the fruits of S. vescum, which, like the preceding, is not agreeable till fully ripe, when it is said to resemble in form and flavour the fruits of Physalis peruviana. Of other species the leaves are eaten; as those of S. oleraceum in the West Indies and Fiji Islands.

Other species are used as dyes. S. indigoferum, in Brazil, cultivated for indigo. The juice of the fruit of S. gnaphalioides is said to be used to tint the cheeks of the Peruvian ladies, while their sisters of the Canary Isles employ similarly the fruits of S. vespertilia. The fruits of S. saponaceum are used in Peru to whiten linen in place of soap. S. marginatum is used in Abyssinia for tanning leather.

Control

Biological: Over 100 insects are being screened, however none have been effective for nightshade control so far.Nightshades are tolerant to many commonly used herbicides, including sulfonylurea herbicides. These herbicides control other broadleaf weeds and allow nightshade to increase by removing competition from other plants. Residual herbicides are required to control continuous flushes that are possible. Successful nightshade control requires allowing no seed production. Many chemicals can be used for control of nightshade in crop production. Consult your extension office or the PNW Weed Management Handbook for information on the control of nightshade in cropping systems.

Cropland: The first approach for successful nightshade control requires allowing no seed production. Crop rotation is an important tool in nightshade control. Crops that compete vigorously with nightshades should be included in the rotation. Wide row or plant spacing also may result in increased germination of nightshades and other summer annual weed species. Finally, reduction of seed populations in the soil is critical to long-term nightshade control. Nightshade control in every year of the entire rotation is important to reduce the soil seed supply, and nightshade plants must never be allowed to mature their seed. In addition, it has been shown that herbicides should also be rotated from year to year.

Using the same herbicide every year may increase the population of soil microorganisms that break down that herbicide. Overuse of a single herbicide mode of action also allows weeds that are tolerant to that particular herbicide to increase. For example, nightshades are tolerant to the commonly used herbicides pendimethalin (Prowl), trifluralin (Treflan), and metribuzin (Sencor) and sulfonylurea herbicides. These herbicides are effective in controlling other weed species, so they may actually allow nightshade to grow with less weed competition, resulting in greater nightshade seed production. A healthy stand of winter wheat will provide strong competition and shading of the soil surface at the time when night- shade seeds germinate. Further, nightshade seedlings that do begin to grow can be effectively controlled by small grain herbicides such as bromoxynil (Buctril), 2,4-D, dicamba (Clarity), and clopyralid + 2,4-D (Curtail), any of which can dramatically reduce nightshade seed production. For heavy nightshade infestations, consider herbicide combinations. Black nightshade has been hard to control with EPTC (Eptam) but is more easily controlled with metribuzin (Sencor) than hairy and cutleaf nightshades. Hairy nightshade is controlled by rimsulfuron (Matrix), but cutleaf nightshade is not. Black nightshade is more easily controlled by triflusulfuron (UpBeet) or s-metolachlor (Dual Magnum) than is hairy nightshade, while phenmedipham + desmedipham (Betamix) is generally better on hairy nightshade than on black nightshade. At the highest labeled rate, dimethenamid-p (Outlook) provides good to excellent black and hairy nightshade control, while ethofumesate (Nortron), cycloate (Ro-Neet), and pyrazon (Pyramin) provide fair to good nightshade control. Often, herbicide combinations are required when multiple nightshade infestations occur.

Non-cropland: Auxinic herbicides (such as 2,4-D, dicamba (Banvel or Weedmaster), clopyralid (Curtail), picloram (Tordon), and others are among the best foliar-applied materials. Applications of these products provide good to excellent control of nightshade species. Other herbicides also show good activity, including glyphosate (Roundup and others), imazapyr (Arsenal), and imazapic (Plateau).

Refer to the label for all herbicides
Always follow label directions prior to use

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Questions: contact Steve Van Vleet or phone (509) 397 - 629