Management and Control of Nightshade Nightshades have become serious weed problems in North Dakota crop production. Human activity associated with crop production is the greatest contributor to nightshade seed dissemination. However, birds and other wildlife consume nightshade and can transport seed through droppings. Moving tillage and harvesting equipment from field to field or planting crop seed contaminated with nightshade seed easily spreads seed. Three different nightshades are found in North Dakota: eastern black nightshade, hairy nightshade, and cutleaf nightshade. Eastern black nightshade is most abundant and is found in eastern North Dakota. Cutleaf nightshade occurs primarily in the northern region of the state but is found in isolated areas in or near the Red River Valley. Hairy nightshade and eastern black nightshade look very similar. Nightshade should be correctly identified because some herbicides that effectively control eastern 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. Half of the berry is covered by a calyx. Eastern black nightshade leaves are dark green, not covered with hair, and may be reddish purple on the lower surface of seedling leaves. Berries are initially green but turn purple as they ripen. The calyx or the petals on top of the berry covers only the top of the berry. 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. Nightshade can compete in several crop environments, including shaded conditions under a dense crop. However, nightshade is very visible after small grain harvest. Growth accelerates after harvest and plants are exposed to sunlight. Nightshade seeds become viable shortly after production and can remain viable in the soil beyond 10 years. Seed buried 8 inches were able to germinate after 30 years. NDSU studies show one nightshade plant can produce 178,000 seeds. Recently, a nightshade plant in Wisconsin was found to produce over 800,000 seeds. Besides being poisonous, the berries cause substantial problems at harvest. Nightshades are frost tolerant and stay green into the harvest season. When nightshades are harvested with beans, the green foliage and juice from ruptured berries can clog combine harvesters. The juice can stain crop seed and cause soil to cling to the beans. The sticky juice of nightshade can glue nightshade seed to bean seed. Growers will spread nightshade to other fields if the seed is used for planting. Dry berries are the same size as soybean seed and are difficult to clean from seed. A major factor responsible for increased nightshade problems in North Dakota is abundant rainfall. Plentiful moisture causes many flushes of nightshade throughout the growing season and late flushes may develop after normal crop spraying is completed. Many herbicides used in crop production are applied early, before most nightshade flushes emerge. Nightshade was less of a problem during the dry years of the late 1980s. Less rainfall will help reduce nightshade flushes and higher temperatures will cause nightshade to germinate earlier and during a shorter duration when many herbicide applications are being made. Nightshades are immune to shading. Crops that canopy late and cultural methods of early planting, late cultivation and wide row spacings allow nightshade to grow and develop faster than the crop. 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. Most row crop herbicides have little residual activity to control continuous nightshade flushes. Residual herbicides are required to control continuous flushes that are possible. Residual herbicides prevent germination but nonresidual herbicides have no activity on emerging flushes. Successful nightshade control requires allowing no seed production. Avoid planting crops contaminated with nightshade seed. Plan a crop rotation where nightshade can be controlled. Plant crops such as small grains or soybean where effective herbicides are labeled for nightshade control. Herbicides effective on small nightshade in small grains include 2,4-D, Banvel, and Curtail. Herbicides that control small and slightly larger nightshade are Buctril, Bronate, and Tordon. Many herbicides can be used to control nightshade in corn. Soil applied herbicides include: Eradicane, Broadstrike + Dual, Broadstrike Plus, Atrazine, DoublePlay, Harness, Surpass, and Lasso. Postemergence herbicides include: Buctril, Banvel, Clarity, and Scorpion III. Scorpion III will provide excellent season-long nightshade control. Herbicides used in beans for nightshade control are Eptam, Lasso, Sonalan, Broadstrike + Dual, Broadstrike + Treflan, Cobra, Blazer, and Pursuit. Basagran is more active on hairy nightshade than eastern black nightshade. Cobra and Blazer are effective only on small nightshade. Most row crop herbicides do not have residual activity to control continuous flushes of nightshade. However, Pursuit and Broadstrike does have residual activity and can provide control several weeks into the season long control. Broadstrike and Pursuit residue can prevent nightshade flushes from emerging during the year of application. The residue can remain in the soil for more than one year, so long term crop rotation must be planned if either of these herbicides are used. Nightshade growing between sugarbeet rows will be killed through cultivation. Nightshade growing in the crop row may escape control. A management program may include soil applied Eptam, Ro-Neet, or Nortron. If nightshade should persist, apply one or more applications of Betamix plus Stinger postemergence when nightshade are in the cotyledon to 2-leaf stage. Eptam or Dual can control or suppress nightshade in potato when combined with Lexone/Sencor. These products control germinating nightshade and will not control emerged nightshade. Cultural management practices are especially important for controlling nightshades in potatoes. Plant after land preparation is completed, when soil temperature and moisture are optimum. Early crop germination will result in the fastest possible growth of the crop to compete with nightshade. The early crop growth will provide greater competition and soil shading against nightshade. In summary, for nightshade control: 1. Eliminate nightshade seed production. 2. Avoid planting crop seed contaminated with nightshade seed. 3. Plant crops (corn, small grains, soybean) that allow use of effective herbicides. 4. Plant broadleaf crops in rows instead of drilled, so cultivation can be used with herbicides to control flushes or plants that survive herbicide treatment.