Analysis of the agronomic interest characteristics for the management of Conyza blakei, Conyza bonariensis, Conyza sumatrensis, and Conyza lorentzii

P Diez De Ulzurrun ,María Eugenia Garavano,Valeria Gianelli ,María B Acedo ,Verónica N Ispizúa

doi:10.31285/agro.24.112

P Diez De Ulzurrun , María Eugenia Garavano + Show 3 more

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https://doi.org/10.31285/agro.24.112

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Abstract

Conyza genus includes herbs of ruderal habit, also referred to weeds in pastures, perennial crops, and no tillage crops. The insuitable 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 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 herbicides sensitivity have been associated with these characteristics. The objective of this work 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 % presented significant differences, being C. sumatrensis, the specie 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 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, requiring the first earlier practices of controls.

Highlights

The genus Conyza Less. belongs to the Asteraceae or Compositae family, it consists of approximately 100 species and its origin is the American continent(1)
It includes annual/biennial and perennial species that are distributed in temperate and subtropical areas(2)(3). They have ruderal habits, of primary succession(4) and usually grow in vacant lots, roadsides and railroads. They have been cited as weeds in pastures and perennial crops, adapting to these little disturbed environments since they are sensitive to soil removal(5)
Thirty-five individuals in pots according to a randomized complete block design (RCBD) were analyzed for each species

Summary

Introduction

The genus Conyza Less. belongs to the Asteraceae or Compositae family, it consists of approximately 100 species and its origin is the American continent(1). Belongs to the Asteraceae or Compositae family, it consists of approximately 100 species and its origin is the American continent(1) It includes annual/biennial and perennial species that are distributed in temperate and subtropical areas(2)(3). They have ruderal habits, of primary succession(4) and usually grow in vacant lots, roadsides and railroads. They have been cited as weeds in pastures and perennial crops, adapting to these little disturbed environments since they are sensitive to soil removal(5). The Conyza species are herbs with simple stems or branched from the base, alternate and sessile leaves, of variable margin, from whole to pinnatisect. The generally pedunculated capitulums are arranged on their own or in secondary inflorescences, they have compressed, glabrous or laxly sericeous achenes with papus formed by a series of sub-equal scabrous bristles(6)(7)

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