Manage Weeds On Your Farm


SARE Outreach
Charles L. Mohler, John R. Teasdale, Antonio DiTommaso | 2021 | 416 pages

Other common names: stramonium, Jamestown weed, thorn apple, mad apple, stinkwort, angel’s trumpet, devil’s trumpet, dewtry, whiteman’s weed, purple thornapple

Datura stramonium L.

Identification of Jimsonweed

Family: Nightshade family, Solanaceae

Habit: Erect, branched, summer annual herb

Description: The seedling is large, with cotyledons that are 1.2–1.6 inch long by 0.2 inch wide, lanceolate, hairless and thick. Cotyledons have an obvious vein, and the petioles have hairs on the upper surface. The seed coat often remains on the cotyledon tips after emergence. The seedling stem gradually turns purple, starting at the base. The first pair of true leaves is opposite, egg to triangle shaped with non-toothed, entire edges, and strongly veined on the underside; the first true leaves appear gray-green due to very small, scattered hairs on the puckered leaf surface. Other young leaves show edge irregularity and have flat hairs only above veins and on the leaf stalk. Mature plants reach 1–6 feet in height and branch in their upper portions. Stems are purple, 1–2 inches thick and have either no hairs or very small, inconspicuous hairs. Leaves are alternate, oval to triangular in outline, and irregularly toothed, giving them an overall oak-leaf appearance. Leaves are dark green, hairless, strongly veined and 2–6 inches long by 1–4 inches wide. The taproot system is shallow, broad, thick and highly divided. The entire plant has a strong, unpleasant odor. Trumpet-shaped, white or purple, solitary flowers sit on stalks arising from leaf-stem junctures on upper plant portions. Flowers have five green, ridged, 1.4–1.8 inch-long sepals covering the base of the five fused petals. The petals are 2–4 inches long and 1–2 inches wide; each petal tip has a pointed, thin projection that extends 0.2–0.3 inch beyond the rim of the flower. Each plant produces up to 50 egg-shaped, 0.8–1.2 inch-long by 0.75 inch-wide, green fruit capsules; the entire fruit is covered with 0.13–0.4 inch-long prickles and spines. The capsule turns brown and splits into four chambers. Capsules of vigorous plants contain approximately 600–700 seeds. Seeds are kidney shaped, flat, black, wrinkled and 0.13–0.14 inch long. 

Similar species: Seedlings of common cocklebur (Xanthium strumarium L.) can be differentiated from those of jimsonweed by their lack of odor and larger, 2 inch-long by 0.4 inch-wide cotyledons. Young common cocklebur leaves are covered with small, rigid hairs, and older leaves do not resemble oak leaves.

Management of Jimsonweed

Because this weed is extraordinarily responsive to nutrients, avoiding over-fertilization, particularly with P and N, is crucial for long-term control. Keep this species controlled around manure and compost storage areas to avoid spreading seeds into fields. Avoid incorporating seeds into the soil after crop harvest, if possible, because jimsonweed is particularly susceptible to loss of viability when the seeds are left exposed on the soil surface.

Jimsonweed is relatively intolerant of crop competition. Its growth form changes when subject to competition, with the plant becoming less branched and sloughing the lower leaves. Even though plants commonly emerge above the canopy of mid-sized crops like soybeans, heavy competition during early growth greatly decreases total productivity and seed set. Thus, steps that increase the competitive ability of the crop are highly desirable. Since most of the jimsonweed plant lies above the canopy of most crops, topping the plants with a mower should greatly decrease both competition with the crop and weed seed production.

Because seedlings commonly emerge from below the working depth of rotary hoes and tine weeders, these implements are relatively ineffective for controlling jimsonweed. Tine weeding should focus on maximizing lateral movement of soil to bury seedlings. In crops that tolerate hilling, bury young seedlings as early as crop growth will permit, since jimsonweed makes rapid vertical growth.

No-till and cover crop surface residue can reduce jimsonweed emergence. Both conditions reduce soil temperature and light at the soil surface, thus depriving jimsonweed seeds of the relatively warm temperatures and light they require for germination. 

Ecology of Jimsonweed

Origin and distribution: The origin of jimsonweed is uncertain but most likely is in tropical South or Central America, although it may have originated in Asia. It now occurs throughout the tropical and temperate regions of the world. It is widespread in southeastern Canada and throughout the United States except for the coldest parts of the Midwest and far west. 

Seed weight: Most population mean seed weights range from 5.6–11.7 mg, but mean weights of 1.8–2.4 mg have been observed for populations near the northern edge of the species range. Seed germination generally increases as seed weight increases, with weights over 6 mg per seed providing greatest germination.

Dormancy and germination: Variable conditions have been reported to break seed dormancy. Seeds are kept dormant by a combination of a hard seed coat and germination inhibitor that eventually washes out of the seed. Seeds buried at 8 inches had no dormancy when exhumed, whereas seeds buried at 2 inches maintained dormancy for one year before losing dormancy after exposure to cold winter temperatures. A large day/night temperature fluctuation of 90/54°F effectively overcame dormancy whereas a smaller fluctuation of 90/81°F did not. Seeds buried in soil at 41–50°F became sensitized to germinate when exposed even briefly to light. In most situations, light is a critical factor in triggering germination. Re-burial of photosensitized seeds can induce dormancy, probably due to volatile compounds in the soil that increase in proportion to depth. Base temperature for germination ranged from 46–52°F. Seeds germinate best at 68–95°F with alternating daily temperatures being most stimulatory. Germination is reduced by low moisture conditions more than that of many other weed species.

Seed longevity: In one experiment, over 91% of seeds buried at 22 inches survived more than 39 years. Seeds did not lose viability when buried 2–8 inches for 22 months in Israel. Most seeds remained viable after burial at 8 inches for 17 years at one location, but all lost viability after three years at another location in Nebraska. First year assessment of seed mortality in these experiments indicated an annual loss rate of 14% and 6%. Based on an experiment in which the seeds were buried at 4 inches, we calculated an average loss per year of about 50%. Annual tillage without allowing seed replacement virtually eliminated a jimsonweed seed bank in six years. Burial of jimsonweed seeds by fall tillage promotes seed survival. The wide range in longevity reported for this species may be related to differences in the duration of hard seed coat integrity. 

Season of emergence: Most seedlings emerge from mid-spring to early summer, but some seedlings continue to appear throughout the summer following rain. Jimsonweed has been categorized as “middle-emerging” relative to other weeds.

Emergence depth: Seedlings emerge well from 0.4–2 inches; a few can emerge from as deep as 4 inches, but none emerge from 6 inches. Seeds on the soil surface have reduced germination. Lower emergence from 1.6 inch in clay than in sandy soils was related to poorer gas exchange in clay soils.

Photosynthetic pathway: C3 

Sensitivity to frost: Jimsonweed is frost sensitive. Seeds in immature capsules do not continue to mature after frost. 

Drought tolerance: Jimsonweed can survive in sandy pastures and similar dry sites but thrives best on fertile soil and high rainfall. This species was more competitive with crops under above-average rainfall than under drought conditions. It has a higher rate of water loss and greater physiological sensitivity to water stress than other weeds. 

Mycorrhiza: No studies have reported on the mycorrhizal status of jimsonweed. 

Response to fertility: Jimsonweed growth responds strongly to nitrogen. It accumulates higher concentrations of N than most crops. Alkaloid content also increases with N. It also shows a strong growth response to P and K. In one study, it was the most responsive to P out of 10 warm-season weeds. The species is commonly found in nutrient-rich sites like barnyards and around manure piles. Jimsonweed tolerates soil pH as low as 4.7, but growth is reduced below pH 5.4.

Soil physical requirements: Jimsonweed does best on good quality agricultural soils but can tolerate a wide range of soil conditions. 

Response to shade: Light shade (25%) stimulates growth of jimsonweed, thereby prompting the plant to grow through partial crop canopies. Moderately heavy shade (75%), however, substantially reduces growth. 

Sensitivity to disturbance: Cut or trampled plants regenerate from buds near the base of the stem. Immature capsules will continue to ripen on cut branches or uprooted plants. 

Time from emergence to reproduction: Flowering begins about five to nine weeks after emergence, with the time to flowering less for later emerging plants and for populations from more northerly latitudes. Each flower is open for only one day. Jimsonweed is indeterminate, so it continues to flower as plants continue growth into late summer. Seeds mature and are capable of germination about one month after fertilization, but capsules usually do not open until about seven weeks after fertilization. In Delaware, plants emerging later than early July failed to produce mature capsules.

Pollination: Jimsonweed usually self-pollinates, but occasionally plants may be cross pollinated by insects. Inbreeding depression of seed production can occur, suggesting the need for outcrossing to maintain vigorous populations.

Reproduction: Vigorous plants at low densities produce up to 50 capsules and 30,000 seeds per plant. In contrast, plants stressed by competition may only produce 1,300–1,500 seeds.

Dispersal: Seeds are dispersed by combines and in soil clinging to tillage implements, tires, shoes and livestock. Seeds can contaminate grain and cover crop seed. Several introductions through contaminated soybean seed have been reported. The seeds and capsules float well and disperse along streams and irrigation ditches. The spines on the capsules are not effective for dispersing the seed. 

Common natural enemies: Three-lined potato beetles (Lema trivittata and L. trilineata) destroy seedlings and can cause severe defoliation of larger plants. Greater damage to foliage from L. trilineata and other herbivores was observed in inbred than in outcrossed populations.

Palatability: Both leaves and seeds are highly toxic to humans and livestock due to alkaloids and sometimes nitrate. Many people have died from grain contaminated with jimsonweed seeds. Since the foliage is extremely unpalatable and poisoning causes loss of appetite, damage to grazing livestock is usually limited.

Summary Table of Jimsonweed Characteristics

Growth habitSeed weight (mg)Seed dormancy at sheddingFactors breaking dormancyOptimum temperature for germination (F)Seed mortality in untilled soil (%/year)Seed mortality in tilled soil (%/year)Typical emergence seasonOptimum emergence depth (inches)
tall, branched6–12Yesscd, cms, li, at68–956–50namid-spring to early summer0.4–2
Photosynthesis typeFrost toleranceDrought toleranceMycorrhizaResponse to nutrientsEmergence to flowering (weeks)Flowering to viable seed (weeks)Pollination Typical & high seed production (seeds per plant)
C3lowlownahigh5–94self, can cross1,500 & 30,000

Table Key

General: The designation “–” signifies that data is not available or the category is not applicable.

Growth habit: A two-word description; the first word indicates relative height (tall, medium, short, prostrate) and second word indicates degree of branching (erect, branching, vining).

Seed weight: Range of reported values in units of “mg per seed.”

Seed dormancy at shedding: “Yes” if most seeds are dormant when shed, “Variable” if dormancy is highly variable, “No” if most seeds are not dormant.

Factors breaking dormancy: The principle factors that are reported to break dormancy and facilitate germination. The order of listing does not imply order of importance. Abbreviations are:

scd = seed coat deterioration

cms = a period subjected to cold, moist soil conditions

wst = warm soil temperatures

li = light

at = alternating day-night temperatures

ni = nitrates

Optimum temperature range for germination: Temperature (Fahrenheit) range that provides for optimum germination of non-dormant seeds. Germination at lower percentages can occur outside of this range. The dash refers to temperature range, and the slash refers to alternating day/night temperature amplitudes.

Seed mortality in untilled soil: Range of mortality estimates (percentage of seed mortality in one year) for buried seeds in untilled soil. Values were chosen where possible for seeds placed at depths below the emergence depth for the species and left undisturbed until assessment. Mortality primarily represents seed deterioration in soil.

Seed mortality in tilled soil: Range of mortality estimates (percentage of seed mortality in one year) for seeds in tilled soil. Values were chosen for seeds placed within the tillage depth and subjected to at least annual tillage events. Seed losses are the result of dormancy-breaking cues induced by tillage, germination and deterioration of un-germinated seeds.

Typical emergence season: Time of year when most emergence occurs in the typical regions of occurrence for each weed. Some emergence may occur outside of this range.

Optimum emergence depth: Soil depths (in inches below the soil surface) from which most seedlings emerge. Lower rates of emergence usually will occur at depths just above or just below this range.

Photosynthesis type: Codes “C3” or “C4” refer to the metabolic pathway for fixing carbon dioxide during photosynthesis. Generally, C3 plants function better in cooler seasons or environments and C4 plants function better in warmer seasons or environments.

Frost tolerance: Relative tolerance of plants to freezing temperatures (high, moderate, low).

Drought tolerance: Relative tolerance of plants to drought (high, moderate, low).

Mycorrhiza: Presence of mycorrhizal fungi. “Yes” if present; “no” if documented not to be present, “unclear” if there are reports of both presence and absence; “variable” if the weed can function either with or without, depending on the soil environment.

Response to nutrients: Relative plant growth response to the nutrient content of soil, primarily N, P, K (high, moderate, low).

Emergence to flowering: Length of time (weeks) after emergence for plants to begin flowering given typical emergence in the region of occurrence. For species emerging in fall, “emergence to flowering” means time from resumption of growth in spring to first flowering.

Flowering to viable seed: Length of time (weeks) after flowering for seeds to become viable.

Pollination: “Self” refers to species that exclusively self-pollinate, “cross” refers to species that exclusively cross-pollinate, “self, can cross” refer to species that primarily self-pollinate, but also cross-pollinate at a low rate, and “both” refers to species that both self-pollinate and cross-pollinate at relatively similar rates.

Typical and high seed production potential: The first value is seed production (seeds per plant) under typical conditions with crop and weed competition. The second value, high seed production, refers to conditions of low density without crop competition. Numbers are rounded off to a magnitude that is representative of often highly variable reported values.

Further Reading 

Pawlek, J.A., D.S. Murray and B.S. Smith. 1990. Influence of capsule age on germination of non-dormant jimsonweed (Datura stramonium) seed. Weed Technology 4: 31–34.

Weaver, S.E. and S.L. Warwick. 1984. The biology of Canadian Weeds. 64. Datura stramonium L. Canadian Journal of Plant Science 64: 979–991.

Zhang, J., M.L. Salas, N.R. Jordan and S.C. Weller. 1999. Biorational approaches to managing Datura stramonium. Weed Science 47: 750–756.