Conyza spp. are known by different popular names, depending on the region.
Some examples include: buva, acatoia, capiçoba, catiçoba, erva lacenta, field daisy, foxtail, flying horse and Canadian buva.
The species that cause the most damage are conyza bonariensis, Conyza canadensis e conyza sumatrensis.
Infested crops
Buva is a weed widely found in soybean, corn and wheat crops, mainly in the Central-West, Southeast and South regions of Brazil.
These crops are especially impacted by buva's resistance to herbicides, such as glyphosate.
Etiology
Conyza spp. belong to the Asteraceae family and have a high seed dispersal capacity, facilitated by the wind.
The seeds germinate mainly during autumn and winter, a period in which many crops are fallow. This favors the development of the plant and its competition with agricultural crops.
Furthermore, buva has the ability to survive in conditions of water deficit and adapts to management systems such as direct planting.
Control
Control of horseweed is challenging due to its resistance to several herbicides, including glyphosate and acetolactate synthase (ALS) inhibitors. Recommended strategies include:
- Chemical control: The use of herbicides on young plants, less than 15 cm in height, is more effective. Chemical management should combine pre-emergent and post-emergent for greater efficiency.
- Early desiccation: Removing vegetation before planting is essential to reduce buva survival and minimize initial competition.
- Crop rotation: Changing crops and modes of action of herbicides helps prevent the selection of resistant biotypes.
- Ground cover: The use of winter cover crops, such as ryegrass, significantly reduces the density of horseweed at the beginning of summer crops.
To learn more about Conyzaspp., click on:
To find out which pesticides are registered for control, click on:
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