The gender Bidens spp. is widely known in Brazil by the popular name picão-preto.
The two most common species that cause agricultural impact are bidens pilosa e Bidens subalternans.
Another species, Bidens alba, is found less frequently, especially in coastal regions
Infested crops
The black thistle is a weed that occurs in several agricultural crops, including:
- Grains: soybeans, corn and wheat.
- Vegetables: lettuce, tomato and potato.
- Perennial crops: coffee and sugar cane.
- Pastures: areas of inadequate management.
The species' adaptability allows it to spread across different cultivation systems, posing challenges for farmers.
Biology
the species bidens pilosa e Bidens subalternans They are annual herbaceous plants that reproduce by seeds.
They have an erect and angular stem, varying from 30 cm to 1,2 m in height.
The leaves have serrated margins, and hairiness varies between species.
The fruits, called achenes, are responsible for efficient dispersion and are characterized by the presence of pointed awns.
the species bidens pilosa predominantly presents three artists, while Bidens subalternans It generally has four edges, with less hairiness.
The flowers also differ: white in B. pilosa and yellow in B. subalternans.
Development conditions
The black beggar has high phenotypic plasticity, which allows it to adapt to different environmental conditions. The main conditions favorable to its development include:
- Temperature: tropical and subtropical climate, widely distributed across all regions of Brazil.
- Soil: prefers fertile soils with good nutrient availability, but can establish itself in degraded environments.
- Luminosity: adaptable to both full sun and shaded areas.
- Life cycle: presents great variation in flowering and fruiting times, allowing its presence throughout the year.
Control
Control of the black beggartick requires integrated strategies due to its resistance to herbicides, especially to ALS (Acetolactate Synthase) enzyme inhibitors. The main management practices include the following:
- Chemical control: use of herbicides with different mechanisms of action, respecting the rotation of active ingredients. Application should occur in the early stages of plant development for greater efficiency.
- Cultural control: crop rotation to reduce selection pressure. And use of cover crops to suppress weed emergence.
- Mechanical control: manual weeding in smaller areas; use of mowing in areas of heavy infestation.
The resistance of the black beggartick to glyphosate has been a growing challenge for producers, requiring constant monitoring and the adoption of good agricultural practices to minimize impacts on production.
To learn more about Bidens spp, click on:
To find out which pesticides are registered for control, click on:
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