Datura stramonium
Since 2003, when atrazine was phased out, datura populations have been steadily increasing in the département. It is found not only in cultivated areas, but also on roadsides, roundabouts, waste ground and gardens. This plant is highly toxic to humans and animals (it contains tropane alkaloids) and spreads very easily. Management of this solanaceous plant is becoming essential.
Biology : Recognition and cycle
The plant : it can grow up to 2 m high and thrives in all types of soil, mainly in summer crops but is now also found in colza. It is characterised by an unpleasant odour when crumpled.
Leaves : apart from slight whitish hairs on very young leaves and petioles, the plant is generally hairless.
Flowers : white, funnel-shaped, up to 10 cm long Fruits or bugs : 4-5 cm long, covered in spines and containing the seeds Seeds : 2.5 to 3.5 mm long
Indicator of : soil pollution by fertilisers or phytosanitary products[1]
Its cycle :
A plant produces from 0 to 500 seeds and emergence is very staggered
| Jan | Feb | March | April | May | June | July | August | Sept | Oct | Nov | Dec | |
|---|---|---|---|---|---|---|---|---|---|---|---|---|
| Germination | x | x | x | x | x | x | ||||||
| Flowering | x | x | x | |||||||||
| Ripening | x | x | x |
The viability of Datura seeds in the soil is over 30 years and they are capable of germinating even at a depth of 15 cm.
Crops concerned
Datura can develop in all summer crops : maize, millet, buckwheat, soya, sunflower, sorghum, but also in carrots, flax, intercropping cover crops, potatoes and oilseed rape, which increases grain stocks.
There is also a risk of contamination of buckwheat, sorghum and millet flours. Crushing the seeds increases toxicity by a factor of 3.
The presence of datura can be a reason for refusing to harvest peas, beans, flageolet, sweetcorn, popcorn, etc.
There is also a risk of poisoning from soya cake. Animals don't eat it when it's ripe, but when the fruit is on the ground at maturity, animals can be poisoned by eating the grass around it.[2]
Regulations
Datura contains tropane alkaloids (atropine and scopolamine) which act on the central nervous system of humans and animals, causing heart problems... As very small quantities cause intoxication, very low levels of tropanic alkaloids have been set in human and animal foodstuffs.
Animal
The current toxic dose for cattle is 600 to 900 mg of seeds per kilo of live weight. Since June 2011, the harvest standard must not exceed 1g per kg of seeds intended for the manufacture of animal feed (European Directive 2002/32).
To date, the ARfD (Acute Reference Value), i.e. the acute toxicity of these tropanic alkaloids, has been set at : 0.016 µg/kg weight, i.e. 1.12µg for a person weighing 70 kg, which corresponds to a very low value, so these alkaloids are highly dangerous.
For Baby Food, the regulations are set at 1µg/kg of atropine and 1µg/kg of scopolamine.
For the 2022 harvest, a draft European regulation plans to set maximum levels for human nutrition on various crops. The regulations would set the conditions for access to the market, which would apply not from the field but from the silo with a view to 1st processing :
- Grain maize : 15 µg/kg of the sum Atropine + Scopolamine
- Popcorn : 5 µg/kg of the sum Atropine + Scopolamine
- Millet and Sorghum (grains and processed products) : 5 µg/kg of the sum Atropine + Scopolamine
- Buckwheat : 10 µg/kg of the sum Atropine + Scopolamine
On average, 1 gram of Datura seed contains 443 µg of tropane alkaloids, or 1 datura sheath = 28 µg of tropane alkaloids, which would be equivalent to looking for 1 datura seed in
- 2 kg of grain maize
- 3 kg of buckwheat
- 6 kg of Millet, Popcorn and Sorghum.
Control methods
Prophylaxis is essential
- Rotation : as long as you take care with your cropping practices, alternating winter, spring and summer crops will limit the threat. However, in problem plots, avoid the frequent return of crops where datura is difficult to destroy, e.g. : sunflower.
- Make sure the crop (e.g. sunflower) is evenly planted, as datura is very sensitive to competition.
- For plants that have not yet gone to seed : uproot them manually, use a rototiller or rotoblade or mulch, including at the edges of fields, ditches and in reel passages. Remove residues from the field, as immature seeds will still complete their cycle and be able to germinate. Plants that have been uprooted have a great capacity to re-sprout.
- For plants that have already gone to seed : As far as possible, remove them from the plot and compost them at 70°C minimum on a watertight platform to ensure that the seeds are not viable.
- Before harvesting : Make sure that the machine arriving in the field is very well cleaned with special grids to prevent it spreading from one plot to another.
Chemicals by crop
Possible active ingredients : mesotrione, mesotrione+S metolachlor, bentazone, imazamox, bromoxynil, clopyralid, flurochloridone, fluroxypyr, isoxaflutole, pethoxamide, tribenuron-methyl, etc.
| Crops | Chemical solutions | Varietal solutions |
|---|---|---|
| Rapeseed (few
autumn crop) |
Pre-emergence : BUTISAN S, CENTIUM 36 CS
Post-emergence : Clopyralid (LONTREL not before 15/02). MOZZAR localised at full rate |
|
| Cereals (little
references as autumn crop) |
Post-emergence : ZYPAR 0.75 L/ha; PIXXARO EC 0.5 L/ha; BOFIX 2.5 L/ha
ALLIE MAX SX, BIPLAY SX |
|
| Sunflower | Pre-emergence : RACER ME, ATIC AQUA 2.6 L/ha | Post-emergence only on tolerant varieties : the herbicides PULSAR 40, PASSAT PLUS, DAVAI and EXPRESS SX are recommended.
very effective Pulsar 40 1.25 L/ha or PROWL 400 2.5 L/ha in pre-emergence then PULSAR 40 1.25 L/ha in post-emergence. EXPRESS SX, if possible in sequence to manage staggered emergence. |
| Maize | Pre-emergence : CAMIX 2.5 L/ha; ISARD 0.8 L/ha + MERLIN FLEXX 1.7 L/ha; DUAL GOLD SAFENEUR 1.1 L/ha + ADENGO XTRA 0.33 L/ha; ISARD / SPECTRUM 1.2-1.4 L/ha; DAKOTA-P
/ WING-P / BELOGA-P 4 L/ha; ALCANCE; ATIC AQUA 2.6 L/ha. Post emergence (early 2/3 leaves) : ISARD 0.8 L/ha + CAPRENO 0.2 L/ha; CAMIX 2.5 L/ha + CAPRENO 0.2 L/ha. nicosulfuron 20g/ha Up to 8 leaves : ELUMIS 0.7 L/ha; nicosulfuron 30g/ha + LAUDIS WG 0.3 KG/ha; SOUVERAIN OD 1.2 L/ha; CONQUERANT 0.4 KG/ha; MONSOON ACTIVE 1 L/ha.
|
|
| Soya | Pre-emergence : MERCANTOR GOLD, PROMAN (average effectiveness)
Post-emergence : PULSAR 40 and DAVAI |
|
| Millet | Pre-emergence : MERCANTOR GOLD;
Post-emergence : CASPER; BASAGRAN; EMBLEM, (end of use on 17/09/2021); ATIC AQUA 2.6 L/ha |
|
| Sorghum | Pre-emergence : MERCANTOR GOLD; ALCANCE 85 to 95%.
efficacy Post emergence : CASPER, ATIC AQUA 2.6 L/ha |
|
| Spring flax | Pre-emergence : CALLIPRIME XTRA
|
|
| Buckwheat | No approved chemical solution : crop to be avoided | |
| Cover crops and meslin | No chemical solution : crop to be avoided | |
| Peas, field beans, spring lentils | Pre-emergence : CENTIUM 36 CS (except lentils), STALLION SYNC TEC 70 to 85% effective (except lentils)
Post emergence : CORUM or BASAGRAN SG (except faba beans and lentils). lentils) |
|
| Potatoes | BASTILLE 1.5 KG/ha + TOUTATIS DAMTEC 2.25 kg/ha. | |
| Beetroot | BETANAL TANDEM 0.7 L/ha (3 passes), or CONVISO ONE 1
L/ha |
|
| Intercropping | Glyphosate 3.5 l (at 360 g/l) |
Mechanical
- To reduce grain storage during the summer period, increase tillage (stubble ploughing and false seeding) to reduce grain storage.
- Ploughing is not useful for weed control
- For mechanical weed control :
- Harrows and rotary hoes are often ineffective or unreliable, mainly because of staggered emergence.
- Hoeing on several occasions is useful, but the daturas must be very young and it must be very dry for several days afterwards, as there is still a risk of transplanting (a particularity of this plant).
Frost
Destruction by frost is not sufficient.
To find out more
- Arvalis : Three tips for managing datura in autumn
- Arvalis : Datura in maize : do everything possible to avoid it
- Arvalis : Understanding the biology of datura for better control in maize
- Arvalis : What herbicide strategies should be implemented to combat datura in maize?
- Datura (Datura stramoine) Context, Biology, Regulations and Control https://centre-valdeloire.chambres-agriculture.fr/fileadmin/user_upload/Centre-Val-de-Loire/122_Inst-Centre-Val-de-Loire/Votre_Chambre/CA41/Actualites_agenda/2021/Images/41_NT2021_Datura_1_.pdf
Appendices
