Abstract

DIEZ DE ULZURRUN, P. et al. Analysis of the agronomic interest characteristics for the management of Conyza blakei, Conyza bonariensis, Conyza sumatrensis, and Conyza lorentzii. Agrociencia Uruguay [online]. 2020, vol.24, n.1, e112.  Epub June 01, 2020. ISSN 1510-0839.  https://doi.org/10.31285/agro.24.112.

Conyza genus includes herbs of ruderal habit, also referred to as weeds in pastures, perennial crops, and no-tillage crops. The unsuitable use of herbicides, the incorrect identification of species, and the lack of monitoring, among others, explain the fact that Conyza species have become a growing problem in production systems under no-tillage. Therefore, the knowledge of the biology and the adaptive response to diverse cultural practices is paramount. Two of the most important characteristics to establish management guidelines are the height and growth stages of these species since their herbicide sensitivity has been associated with these characteristics. The objective of this study was to analyze the results that affect the reproductive success (germination %, fecundity), and the most effective weed control time (height and determination of the phenological stages) of Conyza blakei, C. bonariensis, C. lorentzii, and C. sumatrensis. Trials were conducted at the Agricultural Experimental Station of Balcarce, inta, Argentina. We analyzed 35 individuals of each species. The germination percentage presented significant differences, being C. sumatrensis the species with the highest number of emerged seedlings. The phenological stages also showed differences, being C. bonariensis the species that began to elongate the stem earliest, the first in flowering, and that had the greatest fecundity. The senescence of the 4 species occurred within the first year of growth. The species with greater reproductive success would be C. bonariensis and C. sumatrensis, the first requiring earlier control practices.

Keywords : weeds; stage of development; germination; fecundity; cycle.

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