Different Glyphosate Susceptibility inChloris polydactylaAccessions

Abstract

Glyphosate is now the most widely used herbicide; after years of frequent utilization, resistant weeds were selected, mainly due to widespread adoption of glyphosate-resistant crops and no-tillage sowing system. Increasing difficulty in controllingChloris polydactylawith glyphosate has been noticed in agricultural areas. Here, the susceptibility level of variousC. polydactylaaccessions from Brazil is examined. Two whole-plant studies were conducted to confirm the presence and extent of glyphosate susceptibility among accessions, which involved the application of seven glyphosate doses on four accessions. The four accessions showed different glyphosate susceptibilities. The “Matão” accession presented major tolerance for glyphosate compared to “Palotina” accessions. “Jaboticabal” plants showed an intermediary susceptibility. The resistance factor (RF) was 3.76 between the “Matão” and “Palotina” accessions. All biotypes died at 2,880 g ae ha−1glyphosate.

Influence of the sowing depth and amount of sugarcane straw on the emergence of Chloris polydactyla and Eleusine indica and their control by herbicides applied pre-emergence

“…Currently, the biggest concern is the low susceptibility of 'capim-branco' to glyphosate, which has enabled this species to become a problem plant in areas with the recurrent use of this herbicide. This finding justifies the study of alternative herbicides to control this species (BARROSO et al, 2014).…”

“…The emergence percentage of 'capim-branco' was low, with an estimated maximum value of 29.8% in the treatment without straw at depths of 1.2 and 1.3 cm. A study of the R. cochinchinensis species showed that the emergence of the plants was higher when the seeds were sown on the soil surface, whereas the emergence decreased with the increase in the sowing depth, with no emerged plants observed after a depth of 10 cm (BOLFREY-ARKU et al, 2011). The increase in the amount of straw had a negative effect on the emergence of 'capim-branco', and this effect was enhanced by the increase in the depth.…”

From tolerance to resistance: mechanisms governing the differential response to glyphosate in Chloris barbata

“…14 Chloris barbata (L.) Sw. is widely distributed in the coastal states of Mexico, 14 coinciding with the main citrus-producing regions. It is worth noting that species of the genus Chloris have a certain level of natural tolerance to glyphosate in comparison with species of other genera, [15][16][17][18] which allows these species to survive and reproduce after field herbicide applications lethal to wild plants of other species. 19 The survival of weed individuals after repeated application of the same herbicide or action mechanism is due to evolutionary adaptations resulting in herbicide resistance.…”

Identificação e manejo de biótipos de Chloris polydactyla com resistência ou suscetibilidade diferencial ao glyphosate no Estado do Paraná

“…Aos Suscetibilidade diferencial ou resistência cientifica ocorrem em uma espécie quando há diferença no controle de diferentes biótipos, porém se encontra abaixo da dose recomendada para controle desta espécie a campo (Barroso et al, 2014b). Estudos de Heap (2006) inferem que o surgimento de plantas resistentes é reflexo da evolução da suscetibilidade diferencial de populações de espécies de plantas daninhas.…”