Agronomy Facts 58 Management of Eastern Black Nightshade in Agronomic An Integrated Approach

Eastern black nightshade ( ptycanthum Dun.), an include American black nightshade ( annual broadleaf , is a problem in northeast- Mill.), black nightshade ( L.), and hairy night- ern field production. It is native to the and shade ( Sendtner). Of these three, only commonly found throughout the United States east of the hairy nightshade is found in the northeastern United States. It Rocky Mountains. Nightshade begins germinating in May can be distinguished from eastern black nightshade by the lack and can continue throughout the growing season. Although of red-purple coloration on the lower surface of the , and it can cause reductions in crop yield, more important, it can upon close inspection of the , the calyx (sepals) may cover interfere with the harvest and lower crop quality. as much as half the . Eastern black nightshade is the pre- At soybean harvest time, nightshade foliage is green dominant annual nightshade species in Pennsylvania. and the are still intact. During harvest, the berry juice In addition to the annuals, the perennial smooth causes soil, nightshade , and other foreign materials to groundcherry (Physalis subglabrata) and horsenettle adhere to the grain, producing a pasty mixture that can clog (Solanum carolinense) seedlings look like the eastern black and gum the sieves, cylinders, and augers of combines. If nightshade seedling. However, both of these typically allowed to dry, this mixture can harden, resulting in down- emerge from rootstock, distinguishing them from annuals. time or even costly repairs. The berry juice can stain , Eastern black nightshade is toxic, as are most in potentially resulting in dockage at the mill; in addition, the the nightshade family. All parts of the plant are considered moisture in the berries can cause poor bulk flow of soybeans poisonous, but the green leaves, stems, and seeds are espe- and promote mold formation during storage. cially toxic. The green fruit may be quite poisonous, while Eastern black nightshade is a member of the nightshade the ripe fruit may be relatively nontoxic. The concentrations () family. Although belonging to this family of the are higher following dry conditions and often have many similarities, individual species should be identified lower following damp, rainy periods. The toxic properties carefully because they react differently to many . The are relatively heat stable and not removed by drying. Por- cotyledons of eastern black nightshade are small and green on tions of the plant stored with forage will remain poison- both surfaces with short hairs on the margins. The true leaves ous, so producers must be cautious when feeding livestock are simple, alternate, petioled, ovate, or ovate-lanceolate. The nightshade-contaminated hay. seedling leaves have a red-purple coloration on the lower sur- The toxicity of the green plant material varies from 0.1 face and margins that vary from entire to slightly serrated. to 1 percent of an animal’s body weight. The toxic prin- pubescence (hair) depends on the environment and varies from ciples include tophane and steroidal alkaloids, which com- nearly hairless to moderately hairy. The stem of the eastern monly induce symptoms in farm animals similar to those of black nightshade plant is erect, becomes widely branched, and an overdose, which includes colic, , saliva- reaches 1 to 2 feet in height. As the plant matures, white flow- tion, and vomiting. Very high doses may induce intestinal ers form in umbel-like clusters of four to five star-shaped flow- dysfunction and constipation, loss of coordination, weak- ers each. The fruit is a 3/8-inch, round, green berry that turns ness, tremors, depression, posterior weakness, paralysis, and purplish black at maturity. Each nightshade plant is capable of low heart rate and blood pressure. Clinical signs develop producing up to 1,000 berries. Contained in each berry are 50 rapidly. Most animals succumb or recover within 24 to 48 to 100 round, flattened, tan-colored seeds, each 1/16 inch in hours. Limited therapies are available for treatment. diameter (approximately the size of a pinhead). As with most weeds, an integrated control program Other annual members of the black nightshade complex combining preventive, cultural, mechanical, and chemical that are sometimes confused with eastern black nightshade methods is most effective. EASTERN BLACK NIGHTSHADE

Illustration by Rae Chambers

2 Prevention planting helps control weeds missed by a preemergence Once eastern black nightshade has become established, treatment and provides a good alternative to a prevent it from spreading into new areas. Clean seeds and postemergence herbicide application. Cultivation will not berries from tillage implements and harvest equipment control weeds within the crop rows, nor is it effective on before using them in uninfested areas. Hay, straw, and crop late germinating weeds. Studies have shown that harvesting seed may contain evidence of eastern black nightshade, so soybeans can be difficult with as little as one nightshade purchase it from a reliable source. Avoid spreading con- plant per 10 feet of row; therefore, for soybeans, cultivation taminated manure onto uninfested fields. alone may not be worth the time and extra effort required. To reduce spreading, spot treat isolated patches of eastern black nightshade with an effective herbicide before Chemical Control the plants reach maturity. Birds have been known to eat ripe To ensure effective, safe, and economical herbicide use: eastern black nightshade berries and transport them to unin- • Select the appropriate herbicide for your weed problem fested fields. Spot treating with an herbicide or mowing any and crop. The stage of weed and crop growth, tempera- isolated patches in noncropland or fallow fields can reduce ture, and soil moisture and pH can affect herbicide perfor- the occurrence of this type of spreading. mance. For additional information, refer to the Penn State Agronomy Guide or consult with the extension educator General Cultural Control in your county or another agricultural professional. The germination of eastern black nightshade is sporadic throughout the growing season, making it difficult to • Read the herbicide label carefully and follow the direc- control in many crops; however, crop competition can aid tions. The label provides important information on safe in minimizing spread. Good cultural practices promote use, application, disposal, and storage. healthy crop stands, and the resulting canopy shading helps • Apply herbicides at the proper time. control weeds. The following guidelines will help you Apply the recommended rate to avoid injury, soil resi- maximize cultural control opportunities: • due, and poor control. • Follow soil test recommendations for lime and fertilizer. • Calibrate application equipment several times during the • Plant high-yielding varieties adapted to climate, soil, season to ensure the correct amount of herbicide is applied. and field conditions. • Wear proper protective equipment (PPE) when work- • If soil temperatures and conditions are optimal, plant ing with pesticides. early using narrow row spacing and high plant popula- Learn to predict weed problems. Scout fields regularly tions, when possible. • and record the types and locations of weeds present. • Follow practical integrated pest management programs Use field records to plan an integrated control program. that monitor disease, insects, and weeds, and use ap- Eastern black nightshade is typically not a major prob- propriate control tactics when necessary. lem in corn—it is not very competitive and can be easily • Avoid certain herbicide programs that increase the poten- controlled with many common corn herbicide programs tial for eastern black nightshade problems, such as Classic/ that contain atrazine. However, several other herbicides can chlorimuron plus Harmony/thifensulfuron in soybeans. also be used to control nightshade (Table 1). Control in soybeans can be achieved with effective Mechanical Control herbicides applied PRE (preemergence) and/or POST Mowing, plowing, disking, and cultivating are some of the (postemergence or foliar). The chloroacetamide herbi- more commonly used mechanical methods for field crop cides (e.g., Dual/metolachlor and Harness/acetochlor) will weed control. Existing nightshade infestations in hay crops provide some control of eastern black nightshade. For more or pastures can be controlled by timely mowing or swath- severe infestations, a PRE program that includes flumioxa- ing to prevent seed production. Repeated mowing may be zin (Valor) or sulfentrazone (Authority/Spartan) or POST necessary due to the sporadic germination of the plant. control with a diphenyl ether (e.g., Cobra, Reflex, or Ultra Fall or spring tillage can bury weed seed deep enough Blazer) or Pursuit may be necessary (Table 2). to reduce emergence. This strategy is especially effective An effective herbicide program combined with early for small-seeded weeds such as eastern black nightshade. canopy closure can increase eastern black nightshade Such tillage requires the use of a moldboard plow or anoth- control in soybeans. Early canopy closure can be achieved er tool that will invert the soil and bury the seed. However, through planting in narrow rows or with drilled beans. if soil erosion is a problem, intensive tillage may not be At times, nightshade can present a problem for seedling possible or practical. Less intensive types of tillage such as forages such as alfalfa. To reduce the chance of competition chisel plowing, disking, or field cultivating prior to planting from eastern black nightshade in alfalfa, plant the forage can destroy weeds that have already emerged, but they may crop as early in the spring as possible, well in advance of also stimulate additional weed emergence. nightshade germination. If nightshade becomes a problem in Cultivating row crops removes or buries small weeds alfalfa, use Pursuit herbicide early postemergence or Maestro and makes them less competitive. In corn or soybeans, before daytime temperatures become too warm (see product one or two cultivations during the first six weeks after labels for rates and additional information).

3 Table 1. Corn herbicides for eastern black nightshade control. PRODUCT/ CONTROL HERBICIDE ACRE RATING COMMENTS PRE/Soil-Applied Atrazine 4L 1–2 qt 4L 9 Atrazine is very effective at controlling eastern black nightshade and can be tank- Atrazine 90DF 1.1–2.2 lb mixed with other products. Refer to current product label for additional restrictions 90 DF and use guidelines. There are many products that contain atrazine. Balance Flexx 2SC 3–6 fl oz 9 Balance Flexx provides effective residual control of eastern black nightshade. Corvus (isoxaflutole) also contains isoxaflutole. Dual II Magnum 7.62EC 1.33–2 pt 7+ Dual may be broadcast prior to weed emergence and can provide adequate control of (s-metolachlor) less severe nightshade infestations. For severe infestations, a tank-mix partner should be added or a POST treatment should be applied for season-long control. There are numerous products that include metolachlor and/or atrazine. Harness 7EC (acetochlor) 1.5–2 pt 8+ Acetochlor is similar in activity to Dual but more active on certain broadleaves such as eastern black nightshade. It can be tank-mixed with other products to improve its performance. There are numerous products that include acetochlor and/or atrazine. Lexar EZ 3.7SC 3 qt 9 Products containing mesotrione and/or bicyclopyrone (Group 27) provide residual (mesotrione + s control of eastern black nightshade when applied preemergence. Products that -metolachlor + atrazine) contain similar active ingredients include Acuron XR, Entrax, Lumax, and Trizar, among others. Princep 4L 1–2 qt 4L 9 Simazine provides effective residual control of eastern black nightshade and can Princep 90DF (simazine) 1.1–2.2 lb be tank-mixed with other products. Refer to current product label for additional 90 DF restrictions and use guidelines. There are several products that contain simazine. Zidua SC 4.17L 3.5–4 fl oz 8 Zidua provides residual control of eastern black nightshade. It can be tank-mixed (pyroxasulfone) with other herbicides to improve its performance. Other products that contain pyroxasulfone include Anthem Maxx and Fierce. POST/Foliar-Applied Atrazine 4L, Atrazine 90DF 1–2 qt 8 Consider previous atrazine applications and do not exceed 2.5 pounds of atrazine per acre per year. Apply before nightshade is 3 inches tall and corn is 12 inches tall. Add crop oil concentrate to spray solution to improve control. Atrazine can be tank-mixed with other herbicides. Refer to current product label for additional restrictions and use guidelines. Cadet 0.91EC (fluthiacet) 0.6–0.9 9 Cadet provides effective control of nightshade when applied before it is 2 inches fl oz tall. Cadet can be tank-mixed for improved control of nightshade. Include necessary adjuvants to the spray mixture. Callisto 4SC (mesotrione) and 3 fl oz 9 Products that contain mesotrione can provide foliar control of eastern black other Group 27 herbicides nightshade. Make the application before the weeds reach 5 inches tall. Callisto requires the use of spray adjuvants and can be tank-mixed with other products. Mesotrione-containing products that can be applied POST include Acuron GT, Halex GT, Realm Q, and Revulin Q. Other HPPD (Group 27) herbicides such as Capreno/ Laudis and Impact/Armezon also provide good control of nightshade when applied POST. Clarity 4S 8–16 fl oz 8+ Dicamba-containing products have foliar activity on nightshade when applied before Status (dicamba) 5–8 oz it reaches 4 inches tall. Tank-mix with glyphosate or other effective herbicides to improve control. Glyphosate 0.75–1 lb 8 Glyphosate in Roundup Ready (glyphosate-resistant) corn provides control of ae nightshade before it is 6 inches tall. It can be tank-mixed with other herbicides to provide more consistent control. Liberty 280 2.34SL 32 fl oz 8 For use in LibertyLink or glufosinate-resistant corn varieties. Apply before nightshade (glufosinate) reaches 6 inches tall. Include 3 pounds per acre of ammonium sulfate in the spray solution. It can be tank-mixed with other herbicides for enhanced activity. Generic versions of glufosinate are available. Maestro 2EC (bromoxynil) 1.5–2 pt 9 Apply Maestro when eastern black nightshade is 1 to 6 inches tall and after corn has reached the four-leaf growth stage. Include a proper spray additive with the spray solution. Maestro may cause temporary leaf burning to the crop. Maestro can be tank-mixed with other herbicides. Weed control rating: 10 = 95–100%; 9 = 85–95%; 8 = 75–85%; 7 = 65–75%; 6 = 55–65%; + = upper end of rating scale.

4 Table 2. Soybean herbicides for eastern black nightshade control. PRODUCT/ CONTROL HERBICIDE ACRE RATING COMMENTS PRE/Soil-Applied Dual Magnum 7.64EC 1.33–2 pt 7+ Dual may be broadcast prior to weed emergence and can provide adequate control (s-metolachlor) of less severe nightshade infestations. For severe infestations, a tank-mix partner should be added or a POST treatment should be applied for season-long control. There are numerous products that contain metolachlor. Pursuit 2AS (imazethapyr) 4 fl oz 8 Pursuit will provide fair to good residual control of eastern black nightshade when applied to soil. Additional POST treatments may be required for season-long control. Reflex 2EC (fomesafen) 1.25 pt 8 Reflex will provide fair to good residual control of eastern black nightshade when applied to soil. Additional POST treatments may be required for season-long control. Spartan 4F (sulfentrazone) 6–10 fl oz 8 Sulfentrazone-containing products will provide fair to good residual control of eastern black nightshade when applied to soil. Additional POST treatments may be required for season-long control. Products that contain sulfentrazone include Authority products, BroadAxe XC, Sonic, and a few others. Valor EZ 4SC (flumioxazin) 2.5 fl oz 9 Valor provides effective residual control of nightshade when applied to soil. Products that contain flumioxazin include Envive, Fierce, Kyber, Panther Pro, Trivence, and a few others. Zidua SC 4.17L 3.5–4.5 8 Zidua provides residual control of eastern black nightshade. It can be tank-mixed (pyroxasulfone) fl oz with other herbicides to improve its performance. Other products that contain pyroxasulfone include Anthem Maxx, Fierce, and Zidua Pro. POST/Foliar-Applied Cobra 2EC (lactofen) 12.5 fl oz 8+ Applications should be made to actively growing eastern black nightshade up to the six-leaf stage (5 inches tall). Soybeans should have one to two trifoliate leaves. Include necessary adjuvants in the spray mixture. Cobra often causes temporary foliar injury to soybeans. This product can be tank-mixed and does not provide residual control. Engenia 5S 12.8 fl oz 8+ Apply over-the-top to dicamba-tolerant soybean (Xtend platform) varieties only until June 30. These products can be tank-mixed with other herbicides for Xtendimax 2.9S (dicamba) 22 fl oz improved nightshade control. Refer to product label and Engeniatankmix.com and xtendimaxapplicationrequirements.com for details on approved adjuvants, drift reduction agents, other tank mixtures, drift management, recommended nozzles and pressures, wind speed, boom height, temperature inversions, buffers, susceptible plants, spray equipment cleanout, and other use guidelines that must be followed when using these products. These are restricted-use pesticides. Tavium is a premix of dicamba and s-metolachlor. Enlist One 3.8SL (2,4-D 2 pt 8 Apply over-the-top to 2,4-D–tolerant (Enlist E3) soybean varieties only and before choline) nightshade reaches 6 inches tall. These products can be tank-mixed with other herbicides for improved nightshade control. Refer to product label and Enlist.com for details on use of this product. Glyphosate 0.75–1 lb 8 Glyphosate in Roundup Ready (glyphosate-resistant) soybeans provides control of ae nightshade when applied before it is 4 inches tall. It can be tank-mixed with other herbicides for more consistent control. Liberty 280 2.34SL (glufos- 32 fl oz 8 For use in LibertyLink or glufosinate-resistant soybean varieties. Apply before inate) nightshade reaches 6 inches tall. Include 3 pounds per acre of ammonium sulfate in the spray solution. Tank-mix with other herbicides for enhanced activity. Generic versions of glufosinate are available. Pursuit 2AS (imazethapyr) 4 fl oz 8+ Apply to actively growing eastern black nightshade up to 3 inches in height. Include necessary adjuvants in the spray mixture. Pursuit can be tank-mixed with other herbicides to improve control. Raptor 1AS (imazamox) is similar to Pursuit and provides control of nightshade. Reflex 2EC, Flexstar 1.88EC 1 pt 8+ For best results, apply to actively growing eastern black nightshade with no more than four (fomesafen) true leaves. Include necessary adjuvants in the spray mixture to optimize performance. These products can be tank-mixed with other herbicides to improve control. Ultra Blazer 2SL (acifluorfen) 1.5 pt 8 Applications should be made before nightshade exceeds 2 inches in height. Soybeans should have at least one or two trifoliate leaves. For consistent control, include necessary adjuvants. Do not apply when weeds or crop are under stress. This product can be tank-mixed and does not provide residual control. Weed control rating: 10 = 95–100%; 9 = 85–95%; 8 = 75–85%; 7 = 65–75%; 6 = 55–65%; + = upper end of rating scale.

5 Harvest Aids this herbicide.) Apply in 20 gallons per acre spray volume at If herbicides fail, harvest aids can be used in soybeans. least 15 days before harvest. For indeterminate varieties, ap- Although several harvest aid herbicides are labeled for use in ply when at least 65 percent of the seed pods have reached a soybean, paraquat-containing products (e.g., Gramoxone) pro- mature brown color or seed moisture is 30 percent or less; and vide the most consistent desiccation and quickened berry drop for determinate varieties, apply when plants are mature (i.e., of eastern black nightshade prior to soybean harvest. If the beans are fully developed, half of leaves have dropped, and nightshade plants are still green and have not yet been frosted, remaining leaves are yellowing). In the absence of a harvest apply 10.7 fluid ounce of Gramoxone SL 3.0 plus surfactant aid herbicide, delay the soybean harvest for as long as possible as a harvest aid. (Note: Gramoxone/paraquat is a restricted-use to allow for additional berry drop. Nightshade berries will drop pesticide and special training must be completed before using slowly following maturity or after a hard frost.

Prepared by Dwight D. Lingenfelter, extension weed scientist; Edward L. Werner, former research technician; and William S. Curran, professor emeritus of weed science. extension.psu.edu Penn State College of Agricultural Sciences research and extension programs are funded in part by Pennsylvania counties, the Commonwealth of Pennsylvania, and the U.S. Department of . Where trade names appear, no discrimination is intended, and no endorsement by Penn State Extension is implied. This publication is available in alternative media on request. Penn State is an equal opportunity, affirmative action employer, and is committed to providing employment opportunities to all qualified applicants without regard to race, color, religion, age, sex, sexual orientation, gender identity, national origin, disability, or protected veteran status. © The Pennsylvania State University 2021 Code UC157 08/21pod