Multiple resistance to glyphosate and imazethapyr in Bidens subalternans

Abstract

Glyphosate has been widely used to control greater beggarticks populations that are resistant to acetolactate synthase (ALS) inhibitors in South America. However, herbicide control failures has been observed over the last three growing seasons in grain production areas of Paraguay. In this research, we report the first case of multiple resistance to glyphosate (EPSPs) and imazethapyr (ALS) in greater beggarticks (Bidens subalternans) population from Paraguay. This conclusion was supported by dose-response experiments conducted in two consecutive years (2018 and 2019) with a putative resistant (R) and a susceptible (S) population. Alternative herbicides were also tested for post-emergence control of R population. For glyphosate, the resistant factor (RF) values were 8.8- (2018) and 15.7-fold (2019). For imazethapyr, the RF values were 59- and 58-fold, in 2018 and 2019, respectively. Treatments with 2,4-D, dicamba, 2,4-D + glyphosate, dicamba + glyphosate, lactofen, fomesafen, ammonium-glufosinate, atrazine, and bentazon provided more than 80% control of the R population. This is the first case of multiple resistance to glyphosate and imazethapyr in greater beggarticks (Bidens subalternans) in the world. The mechanisms underlying resistance in this biotype should be evaluated in future research.

Potencial alelopático de extratos de Chloris gayana na germinação de soja e picão-preto

“…Adicionalmente, o picão-preto é uma planta daninha recorrente em solos brasileiros, sendo amplamente utilizada em estudos para validação do potencial alelopático de extratos de plantas (KRENCHINSKI et al, 2017;TIBUGARI et al, 2020). Ademais, casos recentes de resistência a herbicidas inibidores do fotossistema II (FS II) e acetolactato sintase (ALS) foram identificados para a espécie, dificultando o controle químico em pós emergência na cultura da soja (TAKANO et al, 2016;MENDES et al, 2019).…”

Allelopathic Potential of Hesperozygis ringens Extracts on Seed Germination of Soybeans and Beggarticks

“…Productivity is mainly limited by the effects of competing with weeds that can reduce seed productivity by up to 90%, depending on the weed species, population density and genotype used (Horneburg et al, 2017;Zandoná et al, 2018), which results in the chemical control of large agricultural areas. However, an increase in cases of resistance of beggarticks and other plants to herbicide inhibitors of 5-enolpyruvyl shikimate-3-phosphate synthase (EPSPS), photosystem II (PS II) and acetolactate synthase (ALS) is a growing concern, making post-emergence control of soybeans more difficult and increasing control costs (Alcántara-De La Cruz et al, 2016;Takano et al, 2016;Mendes et al, 2019).…”